Methods and servers for establishing a connection between a client system and a virtual machine executing in a terminal services session and hosting a requested computing environment

RELATED APPLICATIONS

0001The present application claims priority to U.S. Provisional Patent Application Ser. No. 60/761,674, entitled “Methods and Systems for Providing Access to a Computing Environment,” filed Jan. 24, 2006, which is incorporated herein by reference.

FIELD OF THE INVENTION

0002The invention generally relates to providing access to computing environments. More particularly, the invention relates to methods and systems for establishing a connection between a client system and a virtual machine hosting a requested computing environment.

BACKGROUND INFORMATION

0003Contemporary computer networks consist of a number of computer systems communicating with other computer systems via communication links. Typically, some of the systems are client machines and other systems are server machines. A server machine may host a variety of application programs that can be accessed and executed by client machines. When a client machine launches an application program, the execution of that application program can occur at either the client machine or the server machine, depending upon the computing model followed by the computer network. In some environments, the server machine executes a virtual machine, which executes the application program and provides output data to the client machine.

0004One drawback of contemporary computer networks is that client machines may be unaware of the application programs and resources available for use on the server machines. In fact, client machines may not even be aware of each available server machine on the network. Additionally, in environments in which a virtual machine provides access to a resource for the client machine, the virtual machine may be relocated from one server machine to another server. In other environments in which a virtual machine provides access to a resource for the client machine, the client machine may not know that a virtual machine provides access to the application program. To find available application programs on a particular server machine, a user of the client machine may need to find and gain access to that server machine and perform a directory listing of the files existing on that server machine. Even then, this listing might not indicate to the user those applications which the user is authorized to use.

0005Moreover, once the user is aware of the application programs on a server machine, often that user must establish a link to those applications. There are software tools to aid the user in creating these links. However, these tools typically require that the user be an administrator with an understanding the details of networking protocols and domains in order to establish the connection.

0006A method for identifying and providing access to virtualized resources available to a user of the client machine, including application programs, desktop environments, and other computing environments provided via virtual machines executing on server machines would be desirable.

SUMMARY OF THE INVENTION

0007In one aspect, problems of current desktop deployment strategies are addressed. An array of inexpensive physical machines may be partitioned into multiple virtual machines, creating a virtual PC for each user. The physical machines may be servers such as rack-mount servers, blade servers, or stand-alone servers. The physical machines may also be workstations or workstation blades or personal computers. A policy-based dynamic deployment system provisions the virtual machines and associates the virtual machine with an execution machine (i.e., a physical machine) and a user. Centralized hosting provides the manageability of server-based computing while the dedicated environment provides the flexibility and compatibility with applications that a desktop PC enables. However, the system has a much lower total cost of ownership—because the system is implemented in software, rather than being dependent on hardware, the system has a much lower total cost of ownership.

0008In another aspect, the hardware lifecycle may be extended by increasing the amount of hardware resources assigned to virtual machines as computational demands increase over time. Additionally, the use of virtualization eases the difficulty in dealing with multiple OS images.

0009In one embodiment, machines are configured to run multiple copies of one or more operating systems (e.g. different versions/releases of WINDOWS from Microsoft Corporation). Users transmit requests for access to computing resources to the deployment system, which may use a configuration policy to decide how (with what physical and/or virtual resources) and where (on which physical machine in the machine farm and on which virtual machine) to provide access to the requested computing resource. The virtual machine can be created on demand, and the requested software resource may be downloaded and installed in the virtual machine as required. Alternatively, the virtual machine may be pre-configured with a plurality of software and/or virtual hardware resources to provide a particular computing environment to the user. The user request is directed to the selected, configured virtual machine and a remote display connection is established between the virtual machine and a remote display client on the user's access device, which will be referred to generally as a “client machine.” Devices such as CD-ROM drives, floppy drives, USB drives and other similar devices that are connected to the client machine are connected and remotely accessible to the virtual machine, thereby allowing the use of these devices in a manner similar to a standard desktop computer.

0010A deployment system may manage a pool of virtual machines (a machine farm) to which new virtual machines can be added on demand. Alternatively, a plurality of software modules, including a session management component and a virtual machine management component may provide management functionality. Executing virtual machines may be migrated from one physical machine to another, under control of the deployment system, to provide load balancing or to facilitate hardware maintenance. Inactive virtual machines may be suspended to free physical computing resources. Active virtual machines may be migrated from one physical machine to another to consolidate them onto a smaller number of physical machines to allow the unused physical machines to be shutdown to save power during off-peak periods or to free the physical resource to be reassigned for a different purpose e.g. process web requests. Suspended virtual machines may be resumed prior to users requiring access. This can be done manually or automatically via policies or preferences or through a learning process by monitoring a user's behavior over time.

0011Performance requirements of the requested resource may be considered when allocating computing resources to virtual machines. For example, a financial analysis package may require twice as many CPU resources as a generic productivity application, such as those included in MICROSOFT OFFICE, manufactured by Microsoft Corporation of Redmond, Wash. A virtual machine providing the financial analysis package may execute on a physical machine determined to have sufficient spare computational capacity, or existing virtual machines may be relocated to other available physical machines to ensure sufficient available capacity on a particular physical machine.

0012Each user is provided a separate virtual machine environment, which provides increased flexibility in that each user may run any version or configuration of an operating system independently of other users and also allows users to run potentially dangerous or destabilizing applications with little risk of affecting other users. This is particularly useful for developers/testers/information technology personnel who frequently need to reinstall and modify the operating system and run potentially destabilizing applications.

0013Since sharing computing resources and CPU scheduling occurs outside of the virtual machine environment, users can run computing-resource intensive resources with no risk of affecting other users. Virtual machines also provide increased security isolation between users. Because each user is running a separate copy of the OS, there is much less chance of security breaches and virus infections over the between-users boundaries than in the shared OS case.

0014A solution is also provided for problems that arise from a situation where, in a hardware-based system of machines, the hardware is mixed, whether due to an initial purchasing decision or due to the acquisition of different types of physical machines over time. Even if initially all of the hardware was uniform, purchasing additional hardware to replace failing modules and increasing the capacity typically leads to non-uniform hardware throughout a machine farm. Even if all hardware is purchased from the same vendor, it is likely that the hardware purchased later will use different chipsets and components, and will require different drivers. Non-uniform hardware has traditionally translated into the need to maintain multiple versions of the operating system images (which means higher costs) and limits flexibility of moving users between machines—because the operating system image may be incompatible—which also translates into higher cost. Virtual machines allow efficient use of the same operating system image even in a hardware farm that includes heterogeneous machines. The use of the same operating system image helps to significantly reduce the management cost.

0015Adding remote display capability (e.g. presentation layer protocols, such as ICA, RDP, or X11) to virtualization techniques allows virtualization to be used for interactive computing. Hosting multiple virtual machines on an execution machine allows better utilization of the available physical computing resources (e.g.: space, power, processing power, processing capacity, RAM, bandwidth, etc.) thereby lowering costs. The use of virtualization also allows hardware to be updated and maintained independently of OS version and specific device drivers hosted in the operating systems or virtual machines. Additionally, virtual machines enhance system security by isolating computing environments from each other.

0016In still another aspect, a method for providing access to a computing environment by a virtual machine launched by a hypervisor executing in a terminal services session, includes the step of receiving a request from a client system for an enumeration of available computing environments. Collected data regarding available computing environments are accessed. Accessed data are transmitted to the client system, indicating to a client system each computing environment available to a user of the client system. A request to access one of the computing environments is received from the client system. A connection is established between the client system and a virtual machine hosting the requested computing environment via a terminal services session, the virtual machine executed by a hypervisor executing in the terminal services session provided by an operating system executing on one of a plurality of execution machines.

0017In one embodiment, for each stored computing environment, a determination is made as to whether that computing environment is available to a user of the client system. In another embodiment, the accessed data transmitted to the client system are displayable at the client system as icons in a graphical user interface window representing computing environments available to a user of the client system. In still another embodiment, the accessed data transmitted to the client system are displayable at the client system as icons in a graphical user interface window representing computing environments unavailable to a user of the client system. In yet another embodiment, the connection between the client system and the virtual machine is established, via the terminal services session, using a presentation layer protocol.

0018In one embodiment, user credentials are received from the client system. In another embodiment, the accessed data are transmitted to the client system responsive to receiving the user credentials. In still another embodiment, the user of the client system is authenticated based on the received user credentials and access is provided to a selected one of the available computing environment images without requiring further input of user credentials by a user of the client system.

0019In one embodiment, information is gathered about the client system and a data set is generated from the gathered information. In another embodiment, the accessed data are transmitted to the client system indicating, responsive to the generated data set, each computing environment available to the client system. In another embodiment, the accessed data are transmitted to the client system indicating, responsive to an application of a policy to the generated data set, each computing environment available to the client system.

0020In one embodiment, a web server receives a request from a client system for an enumeration of available computing environments. In another embodiment, a page template is retrieved from a persistent storage, the web server creates a page describing a display of computing environment images available to the client system, and the created page is transmitted to the client system.

0021In yet another aspect, in a network including a client system and a plurality of servers storing computing environments, a server includes a broker module, a transmitter, a receiver, and a transceiver. The broker module accesses collected data regarding computing environments and determines, for each computing environment, whether that computing environment image is available to a client system. The transmitter sends accessed data to the client system indicating to the client system each computing environment determined to be available to the client system. The receiver receives a request to access one of the available computing environments. The transceiver provides a connection between the client system and a virtual machine providing the requested computing environment, the virtual machine executed by a hypervisor executing in a terminal services session provided by an operating system executing on one of a plurality of execution machines.

0022In one embodiment, the receiver receives user credentials from the client system. In another embodiment, the server further comprises a database storing the collected data. In still another embodiment, the broker module determines for each computing environment whether that computing environment image is available to a client system based on the user credentials and the collected data.

0023In one embodiment, the server further comprises an output display creation engine creating output displays indicating each computing environment available to the client system. In another embodiment, the output display creation engine creates a web page describing a display of the computing environments available to a client system, the web page created responsive to the collected information and a web page template. In still another embodiment, transceiver provides a connection between the client system and a virtual machine providing the requested computing environment by establishing a presentation layer protocol connection.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of this invention will be readily apparent from the detailed description below and the appended drawings, which are meant to illustrate and not to limit the invention, and in which:

<figref idref="DRAWINGS">FIG. 1</figref> is a block diagram of one embodiment of an environment in which a client machine accesses a computing resource provided by a remote machine;

<figref idref="DRAWINGS">FIGS. 1A and 1B</figref> are block diagrams depicting embodiments of typical computers useful in embodiments with remote machines or client machines;

<figref idref="DRAWINGS">FIG. 2A</figref> is a block diagram of a system for providing access to a resource;

<figref idref="DRAWINGS">FIG. 2B</figref> is a block diagram of one embodiment of a system in which a client machine can initiate execution of an application program for determining the resource neighborhood of that client machine;

<figref idref="DRAWINGS">FIG. 2C</figref> is a block diagram of an embodiment in which a client machine uses a web browser application to determine its resource neighborhood;

<figref idref="DRAWINGS">FIGS. 3A</figref>, <b>3</b>B, and <b>3</b>C are block diagrams of embodiments of systems of communication among a client machine and multiple remote machines;

<figref idref="DRAWINGS">FIG. 3D</figref> is a block diagram of one embodiment of a system in which a client machine can access a resource from a resource neighborhood web page displayed at that client machine;

<figref idref="DRAWINGS">FIG. 3E</figref> is a block diagram of one embodiment of a system in which a remote machine acts as an intermediary for a machine farm;

<figref idref="DRAWINGS">FIG. 4</figref> is a block diagram of one embodiment of a resource neighborhood application in which a client machine is in communication with one of the remote machines;

<figref idref="DRAWINGS">FIG. 5</figref> is a block diagram of a computing embodiment in which a client machine is in communication with a remote machine having an installed resource neighborhood application program of the invention;

<figref idref="DRAWINGS">FIG. 6A</figref> is a screen shot of an embodiment of a display of a client machine after a resource neighborhood application program is executed;

<figref idref="DRAWINGS">FIG. 6B</figref> is a screen shot of another embodiment of a display screen of a client machine after the resource neighborhood application program is executed;

<figref idref="DRAWINGS">FIG. 7A</figref> is a block diagram of an embodiment of a network providing policy-based access to application programs for a machine;

<figref idref="DRAWINGS">FIG. 7B</figref> is a block diagram depicting a more detailed embodiment of a policy engine;

<figref idref="DRAWINGS">FIG. 8</figref> is a flowchart depicting one embodiment of a process for providing access to a resource;

<figref idref="DRAWINGS">FIG. 9</figref> is a flow diagram depicting one embodiment of a process for electing a management node;

<figref idref="DRAWINGS">FIG. 10</figref> is a flow diagram depicting one embodiment of a process to update information collected by the management node;

<figref idref="DRAWINGS">FIG. 11</figref> is a block diagram depicting an embodiment of a machine farm including first and second network management processes;

<figref idref="DRAWINGS">FIG. 12</figref> is a block diagram depicting one embodiment of a virtual machine management component;

<figref idref="DRAWINGS">FIG. 13</figref> is a block diagram depicting one embodiment of a session management component;

<figref idref="DRAWINGS">FIG. 14</figref> is a block diagram depicting one embodiment of a system in which a drive associated with the client machine <b>10</b> is made available to a computing environment;

<figref idref="DRAWINGS">FIG. 15A</figref> is a block diagram depicting one embodiment of a client machine supporting multiple client machine display devices;

<figref idref="DRAWINGS">FIG. 15B</figref> is a block diagram depicting one embodiment of a system for supporting multiple client machine display devices

<figref idref="DRAWINGS">FIG. 15C</figref> is a block diagram depicting one embodiment of a session login mechanism providing support for multiple client machine display devices;

<figref idref="DRAWINGS">FIG. 16A</figref> is a flow diagram depicting one embodiment of the steps to be taken to provide a desired display layout to a client machine having multiple display devices;

<figref idref="DRAWINGS">FIG. 16B</figref> is a flow diagram depicting one embodiment of a process to modify a window message;

<figref idref="DRAWINGS">FIG. 16C</figref> is a flow diagram depicting one embodiment of the steps taken to associate a display layout with a client machine;

<figref idref="DRAWINGS">FIG. 16D</figref> is a flow diagram depicting one embodiment of the steps taken to change a desired display layout for a client machine;

<figref idref="DRAWINGS">FIG. 17</figref> is a block diagram depicting one embodiment of a system in which a remote machine authenticates the user of a client machine;

<figref idref="DRAWINGS">FIG. 18</figref> is a flow diagram depicting one embodiment of the steps taken to access a plurality of files comprising an application program;

<figref idref="DRAWINGS">FIG. 19</figref> is a block diagram depicting one embodiment of a client machine <b>10</b> including an application streaming client, a streaming service and an isolation environment;

<figref idref="DRAWINGS">FIG. 20</figref> is a flow diagram depicting one embodiment of steps taken by a client machine to execute an application;

<figref idref="DRAWINGS">FIG. 21</figref> is a block diagram depicts one embodiment of a plurality of application files;

<figref idref="DRAWINGS">FIG. 22A</figref> is a flow diagram depicting one embodiment of the steps taken to enable transparent distributed program execution on a remote machine through the selection of graphical indicia representative of a data file located on the client machine;

<figref idref="DRAWINGS">FIG. 22B</figref> is a flow diagram depicting one embodiment of the steps taken by a remote machine to enable transparent distributed program execution on a remote machine through the selection of graphical indicia representative of a data file located on the client machine;

<figref idref="DRAWINGS">FIG. 23</figref> is a flow diagram depicting another embodiment of the steps taken to enable transparent distributed program execution on a client machine through the selection of graphical indicia representative of a data file located on a remote machine;

<figref idref="DRAWINGS">FIG. 24</figref> is a flow diagram depicting one embodiment of the steps taken to negotiate the protocol for a connection between a client machine and a remote machine;

<figref idref="DRAWINGS">FIG. 25</figref> is a block diagram depicting an embodiment of a remote machine and a client machine establishing a protocol stack for communication;

<figref idref="DRAWINGS">FIG. 26</figref> is a block diagram depicting one embodiment of a client machine architecture;

<figref idref="DRAWINGS">FIG. 27</figref> is a block diagram depicting one embodiment of communication between a client machine and a machine farm;

<figref idref="DRAWINGS">FIG. 28</figref> is a block diagram depicting one embodiment of a client machine architecture;

<figref idref="DRAWINGS">FIG. 29</figref> is a flow diagram depicting one embodiment of the steps taken to display application output in a web page;

<figref idref="DRAWINGS">FIG. 30</figref> is a flow diagram depicting one embodiment of the steps taken link to a virtual machine identified by a hyperlink configuration file;

<figref idref="DRAWINGS">FIG. 31</figref> is a block diagram depicting an embodiment of a system architecture in which a multiplexer is used to transmit data to more than one client machine;

<figref idref="DRAWINGS">FIG. 32</figref> is a block diagram depicting another embodiment of a system architecture in which a multiplexer is used to transmit data to more than one client machine;

<figref idref="DRAWINGS">FIG. 33</figref> is a block diagram depicting one embodiment of an architecture for displaying application output in a web page;

<figref idref="DRAWINGS">FIG. 34</figref> is a block diagram depicting another embodiment of an architecture for displaying application output in a web page;

<figref idref="DRAWINGS">FIG. 35</figref> is a block diagram depicting another embodiment of an architecture for displaying application output in a web page;

<figref idref="DRAWINGS">FIG. 36</figref> is a block diagram depicting another embodiment of an architecture for displaying application output in a web page;

<figref idref="DRAWINGS">FIG. 37</figref> is a block diagram depicting one embodiment of a client machine receiving window attribute data via a virtual channel;

<figref idref="DRAWINGS">FIG. 38</figref> is a block diagram depicting a client machine connected to more than one remote machine;

<figref idref="DRAWINGS">FIG. 39</figref> is a flow diagram depicting one embodiment of the steps taken to detect and transmit server-initiated display changes;

<figref idref="DRAWINGS">FIG. 40</figref> is a flow diagram depicting one embodiment of the steps taken to detect and transmit client-initiated display changes;

<figref idref="DRAWINGS">FIG. 41</figref> is a flow diagram depicting one embodiment for enabling transmission of seamless windows between a client machine and a remote machine;

<figref idref="DRAWINGS">FIG. 42</figref> is a block diagram depicting one embodiment of an agent;

<figref idref="DRAWINGS">FIG. 43</figref> is a block diagram depicting one embodiment of a system for enabling seamless windowing mode between a client machine and remote computing environments;

<figref idref="DRAWINGS">FIG. 44</figref> is a flow diagram depicting one embodiment of the steps taken in a method of receiving window attribute data and graphical data associated with remote windows from virtualized operating systems and from native operating systems;

<figref idref="DRAWINGS">FIG. 45</figref> is a block diagram of a system for providing a client with a reliable connection to a host service according to an embodiment of the invention;

<figref idref="DRAWINGS">FIG. 46</figref> is a block diagram of a system for providing a client with a reliable connection to a host service according to another embodiment of the invention;

<figref idref="DRAWINGS">FIG. 47</figref> depicts communications occurring over a network according to an embodiment of the invention;

<figref idref="DRAWINGS">FIG. 48</figref> depicts communications occurring over a network according to another embodiment of the invention;

<figref idref="DRAWINGS">FIG. 49</figref> depicts a process for encapsulating a plurality of secondary protocols within a first protocol for communication over a network according to an embodiment of the invention;

<figref idref="DRAWINGS">FIG. 50</figref> is a block diagram of an embodiment of a computer system to maintain authentication credentials in accordance with the invention;

<figref idref="DRAWINGS">FIG. 51</figref> is a flow diagram of the steps followed in an embodiment of the computer system of <figref idref="DRAWINGS">FIG. 5</figref> to maintain authentication credentials during a first communication session in accordance with the invention;

<figref idref="DRAWINGS">FIG. 52</figref> is a flow diagram of the steps followed in an embodiment of the computer system of <figref idref="DRAWINGS">FIG. 50</figref> to maintain authentication credentials during a second communication session following the termination of the first communication session of <figref idref="DRAWINGS">FIG. 53A</figref> in accordance with the invention;

<figref idref="DRAWINGS">FIG. 53</figref> is a block diagram of an embodiment of a computer system to maintain authentication credentials in accordance with another embodiment of the invention;

<figref idref="DRAWINGS">FIG. 54</figref> is a flow diagram of the steps followed in an embodiment of the computer system of <figref idref="DRAWINGS">FIG. 53</figref> to maintain authentication credentials during a first communication session in accordance with the invention;

<figref idref="DRAWINGS">FIG. 55</figref> is a flow diagram of the steps followed in an embodiment of the computer system of <figref idref="DRAWINGS">FIG. 53</figref> to maintain authentication credentials during a second communication session following the termination of the first communication session of <figref idref="DRAWINGS">FIG. 53</figref> in accordance with the invention;

<figref idref="DRAWINGS">FIG. 56</figref> is a flow diagram of the steps followed in an embodiment of the computer system of <figref idref="DRAWINGS">FIG. 53</figref> to maintain authentication credentials during a second communication session following the termination of a second communication channel of the first communication session of <figref idref="DRAWINGS">FIG. 53</figref> in accordance with the invention;

<figref idref="DRAWINGS">FIG. 57</figref> is a block diagram of a system to maintain authentication credentials and provide a client with a reliable connection to a host service according to an embodiment of the invention;

<figref idref="DRAWINGS">FIG. 58</figref> is a block diagram of a system to maintain authentication credentials and provide a client with a reliable connection to a host service according to another embodiment of the invention;

<figref idref="DRAWINGS">FIG. 59</figref> is a block diagram of a system to maintain authentication credentials and provide a client with a reliable connection to a host service according to another embodiment of the invention;

<figref idref="DRAWINGS">FIG. 60</figref> is a block diagram of a system to maintain authentication credentials and provide a client with a reliable connection to a host service according to another embodiment of the invention;

<figref idref="DRAWINGS">FIG. 61</figref> is a block diagram of a system for providing a client with a reliable connection to a host service and further including components for reconnecting the client to a host service according to an embodiment of the invention;

<figref idref="DRAWINGS">FIG. 62</figref> is a block diagram of an embodiment of a system for providing a client with a reliable connection to a host service and further including components for reconnecting the client to a host service;

<figref idref="DRAWINGS">FIG. 63</figref> is a block diagram of an embodiment of <figref idref="DRAWINGS">FIG. 61</figref> further including components for initially connecting the client to a host service;

<figref idref="DRAWINGS">FIG. 64</figref> is a block diagram of the system of <figref idref="DRAWINGS">FIG. 62</figref> further including components for initially connecting the client to a host service and to maintain authentication credential according to an embodiment of the invention;

<figref idref="DRAWINGS">FIG. 65</figref> is a flow diagram of a method for network communications according to an embodiment of the invention;

<figref idref="DRAWINGS">FIG. 66</figref> is a flow diagram of a method for reconnecting the client to the host services;

<figref idref="DRAWINGS">FIGS. 67-69</figref> are flow diagrams of a method for connecting a client to a plurality of host services according to an embodiment of the invention;

<figref idref="DRAWINGS">FIG. 70</figref> is a flow diagram of a method for providing a client with a reliable connection to host services and for reconnecting the client to the host services according to an embodiment of the invention;

<figref idref="DRAWINGS">FIGS. 71-72</figref> are flow diagrams of a method for reconnecting a client to host services according to an embodiment of the invention;

<figref idref="DRAWINGS">FIG. 73</figref> is a conceptual block diagram of an embodiment of client software and server software;

<figref idref="DRAWINGS">FIG. 74</figref> is a flow chart of an embodiment of a method for monitoring network performance;

<figref idref="DRAWINGS">FIG. 75</figref> is a flow chart of an embodiment of a method of operation of the server software;

<figref idref="DRAWINGS">FIG. 76</figref> is a flow chart of an embodiment of a method of generating sub-metrics by the client;

<figref idref="DRAWINGS">FIG. 77</figref> is a flow chart of an embodiment of a method of generating sub-metrics by the client;

<figref idref="DRAWINGS">FIG. 78</figref> is a flow chart of an embodiment of a method of generating sub-metrics by the server;

<figref idref="DRAWINGS">FIG. 79</figref> is a schematic diagram depicting a networked client-server computing system;

<figref idref="DRAWINGS">FIG. 80</figref> is a flow chart depicting a method for connecting a client machine to disconnected application sessions;

<figref idref="DRAWINGS">FIG. 81</figref> is a flow chart depicting on embodiment a method for connecting the client machine to active application sessions;

<figref idref="DRAWINGS">FIG. 82</figref> is a schematic diagram depicting one embodiment of a client machine in communication with several remote machines;

<figref idref="DRAWINGS">FIG. 83</figref> is a flow diagram depicting one embodiment of steps taken in a method to connect a user of a client machine to a computing environment;

<figref idref="DRAWINGS">FIG. 84</figref> is a flow diagram depicting an embodiment of steps taken in a method to connect a user of a client machine to a computing environment in response to selection of a graphical user interface element;

<figref idref="DRAWINGS">FIG. 85</figref> is a block diagram depicting one embodiment of a remote machine able to connect the client machine to an application session;

<figref idref="DRAWINGS">FIG. 86</figref> is a block diagram of an embodiment of a system for connecting a client machine to an application session responsive to application of a policy;

<figref idref="DRAWINGS">FIG. 87</figref> is a flow diagram depicting the steps taken in one method to connect a client machine to an application session responsive to application of a policy;

<figref idref="DRAWINGS">FIG. 88</figref> is a block diagram depicting one embodiment of a system for providing, by a virtual machine, access to a computing environment;

<figref idref="DRAWINGS">FIG. 89A</figref> is a block diagram depicting one embodiment of a storage device and a computing device;

<figref idref="DRAWINGS">FIG. 89B</figref> is a flow diagram depicting one embodiment of the steps taken in a method for providing access to a computing environment on a computing device via a storage device;

<figref idref="DRAWINGS">FIG. 90A</figref> is a block diagram depicting one embodiment of a mobile computing device;

<figref idref="DRAWINGS">FIG. 90B</figref> is a flow diagram depicting one embodiment of the steps taken in a method for providing a portable computing environment by a mobile computing device;

<figref idref="DRAWINGS">FIG. 91A</figref> is a block diagram of one embodiment of a mobile computing device and a computing device;

<figref idref="DRAWINGS">FIG. 91B</figref> is a flow diagram depicting depicts one embodiment of the steps taken in a method for providing access to a computing environment on a computing device via a mobile computing device;

<figref idref="DRAWINGS">FIG. 92A</figref> is a block diagram depicting one embodiment of a mobile computing device and a computing device comprising a computing environment selector;

<figref idref="DRAWINGS">FIG. 92B</figref> is a flow diagram depicting an embodiment of the steps taken in a method for establishing a computing environment on a computing device via a mobile computing device;

<figref idref="DRAWINGS">FIG. 93A</figref> is a block diagram depicting one embodiment of a mobile computing device connecting to a docking station;

<figref idref="DRAWINGS">FIG. 93B</figref> is a block diagram depicting one embodiment of a docking station connecting a mobile computing device and a computing device;

<figref idref="DRAWINGS">FIG. 93C</figref> is a block diagram depicting one embodiment of a mobile computing device and computing device having a docking mechanism;

<figref idref="DRAWINGS">FIG. 93D</figref> is a flow diagram depicting one embodiment of the steps taken in a method of providing to a mobile computing device one or more hardware resources;

<figref idref="DRAWINGS">FIG. 94A</figref> is a block diagram depicting one embodiment of a mobile computing device having a plurality of processors;

<figref idref="DRAWINGS">FIG. 94B</figref> is a flow diagram depicting one embodiment of the steps taken in a method for switching, by a mobile computing device, between use of multiple processors;

<figref idref="DRAWINGS">FIG. 95</figref> is a block diagram depicting one embodiment of a system for providing to a first client agent, via a second client agent on a first remote machine, output data generated by a resource executing in a virtual machine provided by a second remote machine;

<figref idref="DRAWINGS">FIG. 96</figref> is a block diagram depicting an embodiment of a system for providing to a first client agent, via a second client agent on a first remote machine, output data generated by a resource executing in a virtual machine provided by a second remote machine; and

<figref idref="DRAWINGS">FIG. 97</figref> is a block diagram depicting one embodiment of a system for identifying, by a coordinator machine, a worker machine providing, via a virtual machine, access to a computing environment.

DETAILED DESCRIPTION OF THE INVENTION

0140Referring now to <figref idref="DRAWINGS">FIG. 1</figref>, a block diagram of one embodiment of an environment in which a client machine <b>10</b>, <b>10</b>′ accesses a computing resource provided by a remote machine, <b>30</b>, <b>30</b>′, <b>30</b>″, <b>30</b>′″ is shown.

0141A remote machine <b>30</b> such as remote machine <b>30</b>, <b>30</b>′, <b>30</b>″, or <b>30</b>′″ (hereafter referred to generally as remote machine <b>30</b>) accepts connections from a user of a client machine <b>10</b>. Although only two client machines <b>10</b> and only four remote machines <b>30</b> are depicted in the embodiment shown in <figref idref="DRAWINGS">FIG. 1</figref>, it should be understood that the system may provide multiple ones of any or each of those components. For example, in one embodiment, the system may include multiple, logically-grouped remote machines <b>30</b>, one or more of which is available to provide a client machine <b>10</b>, <b>10</b>′ access to computing resources. In these embodiments, the logical group of remote machines may be referred to as a “server farm” or “machine farm,” indicated in <figref idref="DRAWINGS">FIG. 1A</figref> as machine farm <b>38</b>. In some of these embodiments, the remote machines <b>30</b> may be geographically dispersed. Thus, the group of remote machines <b>30</b> logically grouped as a machine farm <b>38</b> may be interconnected using a wide-area network (WAN) connection, metropolitan-area network (MAN) connection, a local area network (LAN) a storage-area network (SAN), or a public network such as the Internet. For example, a machine farm <b>38</b> may include remote machines <b>30</b> physically located in geographically diverse locations around the world, including different continents, regions of a continent, countries, regions of a country, states, regions of a state, cities, regions of a city, campuses, regions of a campus, or rooms. Data transmission speeds between remote machines <b>30</b> in the machine farm <b>38</b> can be increased if the remote machines <b>30</b> are connected using a local-area network (LAN) connection or some form of direct connection. A machine farm <b>38</b> may be administered as a single entity.

0142A centralized service may provide management for machine farm <b>38</b>. In some embodiments, one or more remote machines <b>30</b> elect a particular remote machine <b>30</b> to provide management functionality for the farm. The elected remote machine <b>30</b> may be referred to as a management server, management node, or management process. The management node <b>30</b> may gather and store information about a plurality of remote machines <b>30</b>, respond to requests for access to resources hosted by remote machines <b>30</b>, and enable the establishment of connections between client machines <b>10</b> and remote machines <b>30</b>. In other embodiments, an administrator designates one or more remote machines <b>30</b> to provide management functionality for machine farm <b>38</b>.

0143Alternatively, management of the machine farm <b>38</b> may be de-centralized. In some embodiments, one or more remote machines <b>30</b> comprise components, subsystems and modules to support one or more management services for the machine farm <b>38</b>. In one of these embodiments, one or more remote machines <b>30</b> provide functionality for management of dynamic data, including techniques for handling failover, data replication, and increasing the robustness of the machine farm <b>38</b>. In another of these embodiments, one or more remote machines <b>30</b> include communications capabilities to enable the one or more remote machines <b>30</b> to interact with one another to share responsibility for management tasks. Each remote machine <b>30</b> may communicate with a persistent store and, in some embodiments, with a dynamic store.

0144Persistent store may be physically implemented on a disk, disk farm, a redundant array of independent disks (RAID), writeable compact disc, or any other device that allows data to be read and written and that maintains written data if power is removed from the storage device. A single physical device may provide storage for a plurality of persistent stores, i.e., a single physical device may be used to provide the persistent store for more than one machine farm <b>38</b>. The persistent store maintains static data associated with each remote machine <b>30</b> in machine farm <b>38</b> and global data used by all remote machines <b>30</b> within the machine farm <b>38</b>. In one embodiment, the persistent store may maintain the server data in a Lightweight Directory Access Protocol (LDAP) data model. In other embodiments, the persistent store stores server data in an ODBC-compliant database. For the purposes of this description, the term “static data” refers to data that do not change frequently, i.e., data that change only on an hourly, daily, or weekly basis, or data that never change.

0145The data stored by the persistent store may be replicated for reliability purposes physically or logically. For example, physical redundancy may be provided using a set of redundant, mirrored disks, each providing a copy of the data. In other embodiments, the database itself may be replicated using standard database techniques to provide multiple copies of the database. In further embodiments, both physical and logical replication may be used concurrently.

0146As described above, the remote machines <b>30</b> store “static” data, i.e., data that persist across client sessions, in the persistent store. Writing to the persistent store can take relatively long periods of time. To minimize accesses to the persistent store, the remote machines <b>30</b> may develop a logical, common database (i.e., the dynamic store) that is accessible by all of the remote machines <b>30</b> in the machine farm <b>38</b> for accessing and storing some types of data. The dynamic store may be physically implemented in the local memory of a single or multiple remote machines <b>30</b> in the machine farm <b>38</b>. The local memory can be random access memory, disk, disk farm, a redundant array of independent disks (RAID), or any other memory device that allows data to be read and written.

0147In general, data stored in the dynamic store are data that are typically queried or changed frequently during runtime. Examples of such data (hereafter referred to as runtime data) are the current workload level for each of the remote machines <b>30</b> in the machine farm <b>38</b>, the status of the remote machines <b>30</b> in the machine farm <b>38</b>, client session data, the number of virtual machines supported by a remote machine <b>30</b>, the identity of the operating systems supported by a remote machine <b>30</b>, and licensing information.

0148In one embodiment, the dynamic store comprises one or more tables, each of which stores records of attribute-value pairs. Any number of tables may exist, but each table stores records of only one type. Tables are, in some embodiments identified by name. Thus, in this embodiment, two remote machines <b>30</b> that use the same name to open a table refer to the same logical table.

0149The dynamic store (i.e., the collection of all record tables) can be embodied in various ways. In one embodiment, the dynamic store is centralized; that is, all runtime data are stored in the memory of one remote machine <b>30</b> in the machine farm <b>38</b>. That server operates in a manner similar to the management node described above, that is, all other remote machines <b>30</b> in the machine farm <b>38</b> communicate with the server acting as the centralized data store when seeking access to that runtime data. In another embodiment, each remote machine <b>30</b> in the machine farm <b>38</b> keeps a full copy of the dynamic store. Here, each remote machine <b>30</b> communicates with every other remote machine <b>30</b> to keep its copy of the dynamic store up to date.

0150In another embodiment, each remote machine <b>30</b> maintains its own runtime data and communicates with every other remote machine <b>30</b> when seeking to obtain runtime data from them. Thus, for example, a remote machine <b>30</b> attempting to find an application program requested by the client machine <b>10</b> may communicate directly with every other remote machine <b>30</b> in the machine farm <b>38</b> to find one or more servers hosting the requested application.

0151For machine farms <b>38</b> having a large number of remote machines <b>30</b>, the network traffic produced by these embodiments can become heavy. One embodiment alleviates heavy network traffic by designating a subset of the remote machines <b>30</b> in a machine farm <b>38</b>, typically two or more, as “collector points.” Generally, a collector point is a server that collects run-time data. Each collector point stores runtime data collected from certain other remote machines <b>30</b> in the machine farm <b>38</b>. Each remote machine <b>30</b> in the machine farm <b>38</b> is capable of operating as, and consequently is capable of being designated as, a collector point. In one embodiment, each collector point stores a copy of the entire dynamic store. In another embodiment, each collector point stores a portion of the dynamic store, i.e., it maintains runtime data of a particular data type. The type of data stored by a remote machine <b>30</b> may be predetermined according to one or more criteria. For example, remote machines <b>30</b> may store different types of data based on their boot order. Alternatively, the type of data stored by a remote machine <b>30</b> may be configured by an administrator using administration tool <b>140</b>. In these embodiments, the dynamic store is distributed among two or more remote machines <b>30</b> in the machine farm <b>38</b>.

0152Remote machines <b>30</b> not designated as collector points know the remote machines <b>30</b> in a machine farm <b>38</b> that are designated as collector points. A remote machine <b>30</b> not designated as a collector point communicates with a particular collector point when delivering and requesting runtime data. Consequently, collector points lighten network traffic because each remote machine <b>30</b> in the machine farm <b>38</b> communicates with a single collector point remote machine <b>30</b>, rather than with every other remote machine <b>30</b>, when seeking to access the runtime data.

0153The machine farm <b>38</b> can be heterogeneous, that is, one or more of the remote machines <b>30</b> can operate according to one type of operating system platform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond, Wash.), while one or more of the other remote machines <b>30</b> can operate according to another type of operating system platform (e.g., Unix or Linux). Additionally, a heterogeneous machine farm <b>38</b> may include one or more remote machines <b>30</b> operating according to a type of operating system, while one or more other remote machines <b>30</b> execute one or more types of hypervisors rather than operating systems. In these embodiments, hypervisors may be used to emulate virtual hardware, partition physical hardware, virtualize physical hardware, and execute virtual machines that provide access to computing environments. Hypervisors may include those manufactured by VMWare, Inc., of Palo Alto, Calif.; the Xen hypervisor, an open source product whose development is overseen by XenSource, Inc., of Palo Alto; the VirtualServer or virtual PC hypervisors provided by Microsoft or others.

0154In some embodiments, a hypervisor executes on a machine executing an operating system. In one of these embodiments, a machine executing an operating system and a hypervisor may be said to have a host operating system (the operating system executing on the machine), and a guest operating system (an operating system executing within a computing resource partition provided by the hypervisor). In other embodiments, a hypervisor interacts directly with hardware on a machine, instead of executing on a host operating system. In one of these embodiments, the hypervisor may be said to be executing on “bare metal,” referring to the hardware comprising the machine.

0155Remote machines <b>30</b> may be servers, file servers, application servers, appliances, network appliances, gateways, application gateways, gateway servers, virtualization servers, deployment servers, or firewalls. The remote machine <b>30</b> may be an SSL VPN server. The remote machine <b>30</b> may be an application acceleration appliance. For embodiments in which the remote machine <b>30</b> is an application acceleration appliance, the remote machine <b>30</b> may provide functionality including firewall functionality, application firewall functionality, or load balancing functionality. In some embodiments, the remote machine <b>30</b> comprises an appliance such as one of the line of appliances manufactured by the Citrix Application Networking Group, of San Jose, Calif., or Silver Peak Systems, Inc., of Mountain View, Calif., or of Riverbed Technology, Inc., of San Francisco, Calif., or of F5 Networks, Inc., of Seattle, Wash., or of Juniper Networks, Inc., of Sunnyvale, Calif.

0156In some embodiments, a remote machine <b>30</b> comprises a remote authentication dial-in user service, referred to as a RADIUS server. In other embodiments, remote machines <b>30</b> may have the capacity to function as a master network information node monitoring resource usage of other machines in the farm <b>38</b>. In still other embodiments, a remote machine <b>30</b> may provide an Active Directory. Remote machines <b>30</b> may be referred to as execution machines, intermediate machines, broker machines, intermediate broker machines, or worker machines.

0157In one embodiment, remote machines <b>30</b> in the machine farm <b>38</b> may be stored in high-density racking systems, along with associated storage systems, and located in an enterprise data center. In this embodiment, consolidating the machines in this way may improve system manageability, data security, the physical security of the system, and system performance by locating machines and high performance storage systems on localized high performance networks. Centralizing the machines and storage systems and coupling them with advanced system management tools allows more efficient use of machine resources.

0158The client machines <b>10</b> may also be referred to as endpoints, client nodes, clients, or local machines. In some embodiments, the client machines <b>10</b> have the capacity to function as both client machines seeking access to resources and as remote machines <b>30</b> providing access to remotely hosted resources for other client machines <b>10</b>. In some embodiments, remote machines <b>30</b> may request access to remotely-hosted resources. In one of these embodiments, the remote machines <b>30</b> may be referred to as client machines <b>10</b>.

0159In one embodiment, the client machine <b>10</b> communicates directly with one of the client machines <b>30</b> in a machine farm <b>38</b>. In another embodiment, the client machine <b>10</b> executes an application to communicate with the remote machine <b>30</b> in a machine farm <b>38</b>. In yet another embodiment, the client machine <b>10</b> communicates with one of the remote machines <b>30</b> via a gateway, such as an application gateway. In some embodiments, the client machine <b>10</b> communicates with the remote machine <b>30</b> in the machine farm <b>38</b> over a communications link <b>150</b>. Over the communications link <b>150</b>, the client machine <b>10</b> can, for example, request access to or execution of various resources provided by remote machines <b>30</b>, such as applications, computing environments, virtual machines, or hypervisors hosted by or executing on the remote machines <b>30</b>, <b>30</b>′, <b>30</b>″, and <b>30</b>′″ in the machine farm <b>38</b>. The client machine <b>10</b>, <b>10</b>′ receives for display output of the results of execution of the resource or output of interaction between the client machine <b>10</b> and the applications or computing environments provided by the remote machines <b>30</b>. In another of these embodiments, over the communications link <b>150</b>, the client machine <b>10</b> can receive the output of applications executing in one or more virtual machines on a remote machine <b>30</b>, <b>30</b>′, <b>30</b>″, and <b>30</b>′″ in the machine farm <b>38</b>.

0160The communications link <b>150</b> may be synchronous or asynchronous and may be a LAN connection, MAN connection, or a WAN connection. Additionally, communications link <b>150</b> may be a wireless link, such as an infrared channel or satellite band. The communications link <b>150</b> may use a transport layer protocol such as TCP/IP or any application layer protocol, such as the Hypertext Transfer Protocol (HTTP), Extensible Markup Language (XML), Independent Computing Architecture Protocol (ICA) manufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla., or the Remote Desktop Protocol manufactured by the Microsoft Corporation of Redmond, Wash. In one embodiment, the communications link <b>150</b> uses a Wi-Fi protocol. In still another embodiment, the communications link <b>150</b> uses a mobile internet protocol.

0161The communications link <b>150</b> may provide communications functionality through a variety of connections including standard telephone lines, LAN or WAN links (e.g., T1, T3, 56 kb, X.25, SNA, DECNET), broadband connections (ISDN, Frame Relay, ATM, Gigabit Ethernet, Ethernet-over-SONET), and wireless connections or any combination thereof. Connections can be established using a variety of communication protocols (e.g., TCP/IP, IPX, SPX, NetBIOS, Ethernet, ARCNET, SONET, SDH, Fiber Distributed Data Interface (FDDI), RS232, IEEE 802.11, IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, CDMA, GSM, WiMax and direct asynchronous connections). In one embodiment, the remote machine <b>30</b> and the client machine <b>10</b> communicate via any type and/or form of gateway or tunneling protocol such as Secure Socket Layer (SSL) or Transport Layer Security (TLS), or the Citrix Gateway Protocol manufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla. The computer system <b>100</b> may include a network interface comprising a built-in network adapter, network interface card, PCMCIA network card, card bus network adapter, wireless network adapter, USB network adapter, modem or any other device suitable for interfacing the computer system <b>100</b> to any type of network capable of communication and performing the operations described herein.

0162The computer system <b>100</b> may support installation devices, such as a floppy disk drive for receiving floppy disks such as 3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive, a DVD-ROM drive, network interface card, tape drives of various formats, USB device, hard-drive or any other device suitable for installing software, programs, data or files, such as any software, or portion thereof.

0163The computer system <b>100</b> may also include a storage device of any type and form for storing an operating system and other related software, and for storing application software programs. In one embodiment, the storage device includes one or more hard disk drives or redundant arrays of independent disks. In other embodiments, the storage device comprises any type and form of portable storage medium or device, such as a compact flash card, a micro hard drive or pocket drive, embedded flash storage, or USB storage drive. Portable storage devices may be generally referred to by a variety of names, including but not limited to, finger drive, flash disk, flash drive, flash memory drive, jump drive, jump stick, keychain drive, keydrive, memory key, mobile drive, pen drive, thumb drive, thumb key, vault drive, USB drive, or USB stick. Optionally, any of the installation devices or mediums could also provide a storage medium or device.

0164In some embodiments, the client machine <b>10</b> includes a client agent which may be, for example, implemented as a software program and/or as a hardware device, such as, for example, an ASIC or an FPGA. An example of a client agent with a user interface is a Web Browser (e.g., INTERNET EXPLORER manufactured by Microsoft Corp. of Redmond, Wash. or SAFARI, manufactured by Apple Computer of Cupertino, Calif.). The client agent can use any type of protocol, such as a remote display protocol, and it can be, for example, an HTTP client agent, an FTP client agent, an Oscar client agent, a Telnet client agent, an Independent Computing Architecture (ICA) client agent manufactured by Citrix Systems, Inc. of Fort Lauderdale, Fla., or a Remote Desktop Protocol (RDP) client agent manufactured by Microsoft Corporation of Redmond, Wash. In some embodiments, the client agent is configured to connect to the remote machine <b>30</b>. In other embodiments (not shown), the client machine <b>10</b> includes a plurality of client agents, each of which may communicate with a remote machine <b>30</b>, respectively.

0165In many embodiments, the remote machines <b>30</b>, and the client machines <b>10</b>, are provided as computers or computer servers, of the sort manufactured by Apple Computer, Inc., of Cupertino, California, International Business Machines of White Plains, N.Y., Hewlett-Packard Corporation of Palo Alto, Calif. or the Dell Corporation of Round Rock, Tex. In some embodiments, the remote machines <b>30</b> may be blade servers, servers, workstation blades or personal computers executing hypervisors emulating hardware required for virtual machines providing access to computing environments. In these embodiments, a single physical machine may provide multiple computing environments.

0166<figref idref="DRAWINGS">FIGS. 1A and 1B</figref> depict block diagrams of typical computer architectures useful in those embodiments as the remote machine <b>30</b>, or the client machine <b>10</b>. As shown in <figref idref="DRAWINGS">FIGS. 1A and 1B</figref>, each computer <b>100</b> includes a central processing unit <b>102</b>, and a main memory unit <b>104</b>. Each computer <b>100</b> may also include other optional elements, such as one or more input/output devices <b>130</b><i>a</i>-<b>130</b><i>n </i>(generally referred to using reference numeral <b>130</b>), and a cache memory <b>140</b> in communication with the central processing unit <b>102</b>.

0167The central processing unit <b>102</b> is any logic circuitry that responds to and processes instructions fetched from the main memory unit <b>104</b>. In many embodiments, the central processing unit is provided by a microprocessor unit, such as those manufactured by Intel Corporation of Mountain View, Calif.; those manufactured by Motorola Corporation of Schaumburg, Ill.; those manufactured by International Business Machines of White Plains, N.Y.; or those manufactured by Advanced Micro Devices of Sunnyvale, Calif.

0168Main memory unit <b>104</b> may be one or more memory chips capable of storing data and allowing any storage location to be directly accessed by the microprocessor <b>102</b>, such as Static random access memory (SRAM), Burst SRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM), Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended Data Output RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), Burst Extended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM), synchronous DRAM (SDRAM), JEDEC SRAM, PC100 SDRAM, Double Data Rate SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM), Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM).

0169In the embodiment shown in <figref idref="DRAWINGS">FIG. 1A</figref>, the processor <b>102</b> communicates with main memory <b>104</b> via a system bus <b>120</b> (described in more detail below). <figref idref="DRAWINGS">FIG. 1B</figref> depicts an embodiment of a computer system <b>100</b> in which the processor communicates directly with main memory <b>104</b> via a memory port. For example, in <figref idref="DRAWINGS">FIG. 1B</figref>, the main memory <b>104</b> may be DRDRAM.

0170<figref idref="DRAWINGS">FIG. 1A</figref> and <figref idref="DRAWINGS">FIG. 1B</figref> depict embodiments in which the main processor <b>102</b> communicates directly with cache memory <b>140</b> via a secondary bus, sometimes referred to as a “backside” bus. In other embodiments, the main processor <b>102</b> communicates with cache memory <b>140</b> using the system bus <b>120</b>. Cache memory <b>140</b> typically has a faster response time than main memory <b>104</b> and is typically provided by SRAM, BSRAM, or EDRAM.

0171In the embodiment shown in <figref idref="DRAWINGS">FIG. 1A</figref>, the processor <b>102</b> communicates with various I/O devices <b>130</b> via a local system bus <b>120</b>. Various buses may be used to connect the central processing unit <b>102</b> to the I/O devices <b>130</b>, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannel Architecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or a NuBus. For embodiments in which the I/O device is a video display, the processor <b>102</b> may use an Advanced Graphics Port (AGP) to communicate with the display. <figref idref="DRAWINGS">FIG. 1B</figref> depicts an embodiment of a computer system <b>100</b> in which the main processor <b>102</b> communicates directly with I/O device <b>130</b><i>b </i>via HyperTransport, Rapid I/O, or InfiniBand. <figref idref="DRAWINGS">FIG. 1B</figref> also depicts an embodiment in which local busses and direct communication are mixed: the processor <b>102</b> communicates with I/O device <b>130</b><i>a </i>using a local interconnect bus while communicating with I/O device <b>130</b><i>b </i>directly.

0172A wide variety of I/O devices <b>130</b> may be present in the computer system <b>100</b>. Input devices include keyboards, mice, trackpads, trackballs, microphones, and drawing tablets. Output devices include video displays, speakers, inkjet printers, laser printers, and dye-sublimation printers. An I/O device may also provide mass storage for the computer system <b>100</b> such as a hard disk drive, a floppy disk drive for receiving floppy disks such as 3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive, a DVD-ROM drive, DVD-RW drive, DVD+RW drive, tape drives of various formats, and USB storage devices such as the USB Flash Drive line of devices manufactured by Twintech Industry, Inc. of Los Alamitos, California, and the iPod Shuffle line of devices manufactured by Apple Computer, Inc., of Cupertino, California.

0173In some embodiments, the client machine <b>10</b> may comprise or be connected to multiple display devices, which each may be of the same or different type and/or form. As such, any of the I/O devices <b>130</b><i>a</i>-<b>130</b><i>n </i>may comprise a display device or any type and/or form of suitable hardware, software, or combination of hardware and software to support, enable or provide for the connection and use of multiple display devices by the client machine <b>10</b>. For example, the client machine <b>10</b> may include any type and/or form of video adapter, video card, driver, and/or library to interface, communicate, connect or otherwise use the display devices. In one embodiment, a video adapter may comprise multiple connectors to interface to multiple display devices. In other embodiments, the client machine <b>10</b> may include multiple video adapters, with each video adapter connected to one or more of the display devices. In some embodiments, any portion of the operating system of the client machine <b>10</b> may be configured for using multiple displays. In other embodiments, one or more of the display devices may be provided by one or more other computing devices, such as remote machine <b>30</b> connected to the client machine <b>10</b>, for example, via a network. These embodiments may include any type of software designed and constructed to use another computer's display device as a second display device for the client machine <b>10</b>. One ordinarily skilled in the art will recognize and appreciate the various ways and embodiments that a client machine <b>10</b> may be configured to have multiple display devices.

0174In further embodiments, an I/O device <b>130</b> may be a bridge between the system bus <b>120</b> and an external communication bus, such as a USB bus, an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, a FireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, a Gigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, a Super HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus, or a Serial Attached small computer system interface bus.

0175General-purpose computers of the sort depicted in <figref idref="DRAWINGS">FIG. 1A</figref> and <figref idref="DRAWINGS">FIG. 1B</figref> typically operate under the control of operating systems which control scheduling of tasks and access to system resources. In some embodiments, the computers operate under control of hypervisors, which represent virtualized views of physical hardware as one or more virtual machines. Operating systems may execute in these virtual machines to control the virtual machine in a manner analogous to the way a native operating system controls a physical machine. Typical operating systems include: the MICROSOFT WINDOWS family of operating systems, manufactured by Microsoft Corp. of Redmond, Wash.; the MacOS family of operating systems, manufactured by Apple Computer of Cupertino, California; OS/2, manufactured by International Business Machines of Armonk, N.Y.; and Linux, a freely-available operating system distributed by Caldera Corp. of Salt Lake City, Utah, among others.

0176The client machines <b>10</b> and <b>20</b> may be any personal computer (e.g., a Macintosh computer or a computer based on processors manufactured by Intel Corporation of Mountain View, Calif.), Windows-based terminal, Network Computer, wireless device, information appliance, RISC Power PC, X-device, workstation, mini computer, main frame computer, personal digital assistant, television set-top box, living room media center, gaming console, mobile gaming device, NetPC's, thin client, or other computing device that has a windows-based desktop and sufficient persistent storage for executing a small, display presentation program. The display presentation program uses commands and data sent to it across communication channels to render a graphical display. Windows-oriented platforms supported by the client machines <b>10</b> and <b>20</b> can include, without limitation, WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS NT 3.51, WINDOWS NT 4.0, WINDOWS 2000, Windows 2003, WINDOWS CE, Windows XP, Windows Vista, MAC/OS, Java, Linux, and UNIX. The client machines <b>10</b> can include a visual display device (e.g., a computer monitor), a data entry device (e.g., a keyboard), persistent or volatile storage (e.g., computer memory) for storing downloaded application programs, a processor, and a mouse. Execution of a small, display presentation program allows the client machines <b>10</b> to participate in a distributed computer system model (i.e., a server-based computing model).

0177In other embodiments, the general-purpose computers of the sort depicted in <figref idref="DRAWINGS">FIG. 1A</figref> and <figref idref="DRAWINGS">FIG. 1B</figref> may have different processors, operating systems, and input devices consistent with the device and in accordance with embodiments further described herein. The computer system <b>100</b> can be any workstation, desktop computer, laptop or notebook computer, server, handheld computer, mobile telephone or other portable telecommunication device, media playing device, a gaming system, or any other type and/or form of computing, telecommunications or media device that is capable of communication and that has sufficient processor power and memory capacity to perform the operations described herein. For example, the computer system <b>100</b> may comprise a device of the IPOD family of devices manufactured by Apple Computer of Cupertino, California, a PLAYSTATION 2, PLAYSTATION 3, or PERSONAL PLAYSTATION PORTABLE (PSP) device manufactured by the Sony Corporation of Tokyo, Japan, a NINTENDO DS, NINTENDO GAMEBOY, NINTENDO GAMEBOY ADVANCED or NINTENDO REVOLUTION device manufactured by Nintendo Co., Ltd., of Kyoto, Japan, or an XBOX or XBOX 360™ device manufactured by the Microsoft Corporation of Redmond, Wash.

0178For embodiments in which a client machine <b>10</b> is a mobile device, the device may be a JAVA-enabled cellular telephone, such as those manufactured by Motorola Corp. of Schaumburg, Ill., those manufactured by Kyocera of Kyoto, Japan, or those manufactured by Samsung Electronics Co., Ltd., of Seoul, Korea. In other embodiments in which the client machine <b>10</b> is mobile, it may be a personal digital assistant (PDA) operating under control of the PalmOS operating system, such as the devices manufactured by palmOne, Inc. of Milpitas, California. In further embodiments, the client machine <b>10</b> may be a personal digital assistant (PDA) operating under control of the PocketPC operating system, such as the iPAQ devices manufactured by Hewlett-Packard Corporation of Palo Alto, Calif., the devices manufactured by ViewSonic of Walnut, California, or the devices manufactured by Toshiba America, Inc. of New York, N.Y. In still other embodiments, the client machine <b>10</b> is a combination PDA/telephone device such as the Treo devices manufactured by palmOne, Inc. of Milpitas, Calif. In still further embodiments, the client machine <b>10</b> is a cellular telephone that operates under control of the PocketPC operating system, such as those manufactured by Motorola Corp.

0179In some embodiments, a client machine <b>10</b> communicates with a remote machine <b>30</b> to determine an enumeration of resources available to the client machine <b>10</b> or to a user of the client machine <b>10</b>. Resources may include, without limitation, computing environments, applications, documents, and hardware resources. In another of these embodiments, the remote machine <b>30</b> provides the client machine <b>10</b> with address information associated with a remote machine <b>30</b>′ hosting a resource identified by the enumeration of resources. In still another of these embodiments, the client machine <b>10</b> communicates with the remote machine <b>30</b>′ to access the identified resource. In one embodiment, the client machine <b>10</b> executes a resource neighborhood application to communicate with the remote machines <b>30</b> and <b>30</b>′. In some embodiments, each of the remote machines <b>30</b> provides the functionality required to identify and provide address information associated with a remote machine <b>30</b>′ hosting a requested resource.

0180Referring now to <figref idref="DRAWINGS">FIG. 2A</figref>, a block diagram depicts one embodiment of a system for providing access to a resource. In brief overview, a request to enumerate computing resources is transmitted from a client machine <b>10</b> (step <b>202</b>). In some embodiments, the request includes an identification of a user of the client machine <b>10</b>. An enumeration of a plurality of resources available to the user of the requesting machine is provided by the remote machine (step <b>204</b>). The client machine <b>10</b> transmits a request for access to a particular resource included in the enumeration (step <b>206</b>).

0181Still referring to <figref idref="DRAWINGS">FIG. 2A</figref>, and in more detail, the transmitted request is a request for an enumeration of computing environments available to the client machine <b>10</b>. In another embodiment, the request is a request for an enumeration of computing environments supporting a particular application requested for execution by the client machine <b>10</b>. In still another embodiment, the request is a request for access to a computing environment supported by a particular plurality of hardware resources.

0182In some embodiments, information associated with the client machine <b>10</b> or with a user of the client machine <b>10</b> is received with the request. In one of these embodiments, credentials associated with the user, or with a user of the client machine <b>10</b>, are received. In one embodiment, the remote machine <b>30</b> receives a request for an enumeration of available computing environments from the client machine <b>10</b> with the information associated with the client machine <b>10</b>, <b>10</b>′ or the user of the client machine <b>10</b>. In another embodiment, the remote machine <b>30</b> receives a transmission from a policy engine including the information. In still another embodiment, the remote machine <b>30</b> receives a transmission from a collection agent including the information. In yet another embodiment, the remote machine <b>30</b> comprises a component receiving requests and associated information.

0183In some embodiments, a remote machine <b>30</b> functioning as a web server receives communications from the client machine <b>10</b>, <b>10</b>′. In one of these embodiments, the web server forwards the communications to a remote machine <b>30</b>′. In one of these embodiments, the web server forwards the communications to a service on the remote machine <b>30</b>′. In another of these embodiments where communications from the client machine <b>10</b>, <b>10</b>′ are routed to a remote machine <b>30</b>′ by the web server, the remote machine <b>30</b> may be selected responsive to an Internet Protocol (IP) address of the client machine <b>10</b>.

0184In some embodiments, the user provides credentials to the remote machine <b>30</b> via a graphical user interface presented to the client machine <b>10</b>, <b>10</b>′ by the remote machine <b>30</b>. In other embodiments, a remote machine <b>30</b>′″ having the functionality of a web server provides the graphical user interface to the client machine <b>10</b>. In still other embodiments, a collection agent transmitted to the client machine <b>10</b>, <b>10</b>′ by the remote machine <b>30</b> gathers the credentials from the client machine <b>10</b>.

0185In some embodiments, collected data regarding available resources is accessed. In some of these embodiments, collected data regarding computing environments is accessed. In some of these embodiments, the accessed data includes an indication of a virtual machine providing access to one of the computing environments. In one of these embodiments, the accessed data includes an indication of a location of the virtual machine. In other embodiments, the accessed data concerning computing environments includes an indication of a plurality of hardware resources required to support the computing environments. In still other embodiments, the accessed data concerning computing environments includes an indication of a user or type of user authorized to access the computing environments. In yet other embodiments, the accessed data is provided responsive to a request for identification of a computing environment providing access to an application program.

0186In some embodiments, the collected data is stored on a server, such as a remote machine <b>30</b>. In other embodiments, the server is in communication with a database storing the collected data. In still other embodiments, the server collects the data from a plurality of machines <b>30</b> in a machine farm <b>38</b>. In one of these embodiments, the data is received from at least one server responsive to a request for the information concerning the computing environments. In another of these embodiments, the server collects the data from a hypervisor executing on a machine <b>30</b>′ in the machine farm <b>38</b>. In still another of these embodiments, the server collects the data from a management component residing in a guest operating system provided by a virtual machine launched into a hypervisor executing on a machine <b>30</b>′ in the machine farm <b>38</b>.

0187In some embodiments, the data is collected by an intermediate, brokering machine. In one of these embodiments, the brokering machine maintains a database of a status of at least one computing environments and collects information from at least one machine providing access to at least one computing environments. In another of these embodiments, the brokering machine collects information from a virtual machine service component residing in a virtual machine providing the computing environments. In still another of these embodiments, the brokering machine collects information from a virtual machine providing management functionality for a virtual machine providing a computing environment. In yet another of these embodiments, the brokering machine collects information from a hypervisor on which an executing virtual machine provides a computing environment. In other embodiments, the brokering machine comprises a machine <b>30</b> including a brokering module.

0188In some embodiments, a determination is made for each available computing environment as to whether that computing environment is available to a user of the client system. In other embodiments, data is gathered about the client system and a data set is generated from the gathered information. In one of these embodiments, the accessed data is transmitted to the client system with an indication to the client system, made responsive to the generated data set, of each computing environment available to the client system. In another of these embodiments, the accessed data is transmitted to the client system indicating to the client system, responsive to the application of a policy to the generated data set, each computing environment available to the client system. In still another of these embodiments, the indication includes at least one method of access available to the user seeking access to the computing environment. In yet another of these embodiments, the indication includes at least one type of action associated with the computing environment which may be taken by, or on behalf of, the user of the client system.

0189An enumeration of a plurality of resources available to the client machine <b>10</b> is provided (step <b>204</b>). In one embodiment, the enumeration is provided responsive to an application of a policy to received information associated with the user of the client machine <b>10</b> or the remote machine <b>30</b>. In another embodiment, the enumeration is provided responsive to a request from the user for a particular type of computing environment. In still another embodiment, the enumeration is provided responsive to a request from the user for computing environments providing access to a type of application program. In yet another embodiment, the enumeration is provided responsive to a request from the user for computing environments supported by a specified plurality of hardware resources.

0190In some embodiments, an indication is transmitted to the client machine <b>10</b> of a plurality of computing environments available to a user of the client machine <b>10</b>. In one of these embodiments, the indication is generated responsive to accessing collected data associated with the plurality of computing environments. In another of these embodiments, the accessed data is transmitted to the client machine <b>10</b> with an enumeration of computing environments available to the client machine <b>10</b>. In some embodiments, a determination is made, for each stored computing environment, as to whether that computing environment is available to the client machine <b>10</b>. In one embodiment, the collected information is transmitted to the client machine <b>10</b>, the transmitted information displayable at the client machine <b>10</b> as icons in a graphical user interface window representing computing environments available to the client system. In another embodiment, the collected information is transmitted to the client machine <b>10</b>, the transmitted information displayable at the client machine <b>10</b> as icons in a graphical user interface window representing computing environments unavailable to the client machine <b>10</b>.

0191In some embodiments, an enumeration of available computing environments is presented to a user of the client machine <b>10</b>. In other embodiments, an enumeration of applications is presented to a user of the client machine <b>10</b>. In one of these embodiments, a physical machine provides access to an enumerated application. In another of these embodiments, a virtual machine provides access to an enumerated application. In still another of these embodiments, a virtual machine provides access to a computing environment from which a user of the client machine <b>10</b> may access the application. In still other embodiments, an enumeration of standard operating environments (such as a guest operating system pre-configured with a plurality of application programs) is provided to the user of the client machine <b>10</b>.

0192In some embodiments, the enumeration of available resources includes an enumeration of a plurality of actions associated with a requested resource. In one of these embodiments, the enumeration of the plurality of actions enables the user to request execution of a computing environment. In another of these embodiments, the enumeration of the plurality of actions enables the user to request cloning of a computing environment. In still another of these embodiments, the enumeration of the plurality of actions enables the user to request shutdown of a computing environment. In yet another of these embodiments, the enumeration of the plurality of actions enables the user to request that a computing environment be rebooted. In some embodiments, the enumeration of the plurality of actions enables the user to request that a snapshot be taken of an existing state of a computing environment. In other embodiments, the enumeration of the plurality of actions enables the user to request that a previous snapshot of a computing environment be provided.

0193A request is transmitted for access to a particular resource (step <b>206</b>). In one embodiment, a user of the client machine <b>10</b> requests a resource responsive to a received enumeration of available resources. In another embodiment, the user requests a resource independent of a received enumeration. In some embodiments, the user requests a resource by selecting a graphical representation of the resource presented on the client machine <b>10</b> by a client agent. In other embodiments, the user requests a resource by selecting a graphical or textual representation of the resource presented to the user on a web server or other remote machine <b>30</b>′″.

0194In some embodiments, the user requests an action associated with a resource. In one of these embodiments, the user requests execution of the resource. In another of these embodiments, the user requests termination of the resource. In still another of these embodiments, the user requests transmission of the resource, including transmission across an application streaming session. In yet another of these embodiments, the user requests that a resource be shutdown. In other embodiments, a request to execute an application is received from the client machine <b>10</b>, the requested application requiring one of the computing environments. In still other embodiments, a request to access a file is received from the client machine <b>10</b>, the requested file requiring execution within one of the computing environments.

0195Still referring to <figref idref="DRAWINGS">FIG. 2A</figref>, a remote machine <b>30</b> launches the Resource Neighborhood (RN) application and presents results of the RN application to the client machine <b>10</b>. The remote machine <b>30</b> can launch the RN application <b>241</b> in response to a request <b>202</b> by the client machine <b>10</b> for an enumeration of available resources. The remote machine <b>30</b> provides an enumeration of available resources to the client machine <b>10</b> (step <b>204</b>). The client machine <b>10</b> and remote machine <b>30</b>′ establish a connection (arrows <b>245</b> and <b>246</b>). By this connection, the remote machine <b>30</b>′ can transfer the executable code of the particular application to the client machine <b>10</b>, when the client machine <b>10</b> and remote machine <b>30</b>′ are operating according to the client-based computing model. Alternatively, the remote machine <b>30</b>′ can execute the particular application and transfer the graphical user interface to the client machine <b>10</b>, when the client machine <b>10</b> and remote machine <b>30</b>′ are operating according to the server-based computing model. In some embodiments the remote machine <b>30</b>′ can execute the Resource Neighborhood application <b>241</b> and push the results back to the client machine <b>10</b> so that when the client machine <b>10</b> requests the Resource Neighborhood application, the Resource Neighborhood results are already available at the client machine <b>10</b>.

0196<figref idref="DRAWINGS">FIG. 2B</figref> shows another embodiment of a system in which the client machine <b>10</b> initiates execution of the Resource Neighborhood application <b>241</b> and a remote machine <b>30</b> presents the results of the RN application <b>241</b> to the client machine <b>10</b>. The client machine <b>10</b> launches the Resource Neighborhood application (e.g., by clicking on a Resource Neighborhood icon representing the application <b>241</b>). In response, the client machine <b>10</b> directs a request <b>202</b> for the Resource Neighborhood application to the remote machine <b>30</b>. The remote machine <b>30</b> can execute the Resource Neighborhood application <b>241</b>, if the application is on the remote machine <b>30</b>, and return the results to the client machine <b>10</b>. Alternatively, the remote machine <b>30</b> can indicate (arrow <b>204</b>) to the client machine <b>10</b> that the Resource Neighborhood application <b>241</b> is available on another remote machine, in this example remote machine <b>30</b>′. The client machine <b>10</b> and remote machine <b>30</b>′ establish a connection (arrows <b>206</b> and <b>210</b>) by which the client machine <b>10</b> requests execution of the Resource Neighborhood application <b>241</b>. The remote machine <b>30</b>′ can execute the application <b>241</b> and transfer the results (i.e., the graphical user interface any audio output etc.) to the client machine <b>10</b>.

0197<figref idref="DRAWINGS">FIG. 2C</figref> shows another embodiment of a system in which a client machine <b>10</b> initiates execution of the Resource Neighborhood application <b>241</b>, in this example via the World Wide Web. A client machine <b>10</b> executes a web browser application <b>280</b>, such as NETSCAPE NAVIGATOR, manufactured by Netscape Communications, Inc. of Mountain View, Calif., INTERNET EXPLORER, manufactured by Microsoft Corporation of Redmond, Wash., or SAFARI, manufactured by Apple Computer of Cupertino, Calif.

0198The client machine <b>10</b>, via the web browser <b>280</b>, transmits a request <b>282</b> to access a Uniform Resource Locator (URL) address corresponding to an HTML page residing on remote machine <b>10</b>. In some embodiments, the first HTML page returned <b>284</b> to the client machine <b>10</b> by the remote machine <b>30</b> is an authentication page that seeks to identify the client machine <b>10</b> or the user of the client machine <b>10</b>.

0199The authentication page allows the client machine <b>10</b> to transmit user credentials, via the web browser <b>280</b>, to the remote machine <b>30</b> for authentication. Transmitted user credentials are verified either by the remote machine <b>30</b> or by another remote machine <b>30</b> in the farm <b>38</b>. This allows a security domain to be projected onto the remote machine <b>30</b>. For example, if the remote machine <b>30</b> runs the WINDOWS NT operating system, manufactured by Microsoft Corporation of Redmond, Wash., and the authenticating machine runs the UNIX operating system, the UNIX security domain may be said to have been projected onto the remote machine <b>30</b>. User credentials may be transmitted “in the clear,” or they may be encrypted. For example, user credentials may be transmitted via a Secure Socket Layer (SSL) connection, which encrypts data using algorithms such as the RC4 algorithm, manufactured by RSA Security Inc. of Bedford, Mass.

0200In some embodiments, an access control decision is made based on received information about the user resources available to the user of the client system are identified responsive to the access control decision. In other embodiments, a policy is applied to the received information about the user. The remote machine <b>30</b> may verify the user credentials received from the client machine <b>10</b>. Alternatively, the remote machine <b>30</b> may pass the user credentials to another remote machine for authentication. In this embodiment, the authenticating server may be in a different domain from the remote machine <b>30</b>. Authenticated user credentials of the client machine <b>10</b> may be stored at the client machine <b>10</b> in a per-session cookie, in fields that are not displayed by the web browser <b>280</b>, or in any other manner common in maintenance of web pages. In some embodiments, a machine farm <b>38</b> with which the remote machine <b>30</b> is associated may allow guest users, i.e., users that do not have assigned user credentials, to access resources hosted by the farm <b>38</b>. In these embodiments, the authentication page may provide a mechanism for allowing a client machine <b>10</b> to identify that it is a guest user, such as a button or menu selection. In other of these embodiments, the remote machine <b>30</b> may omit the authentication page entirely.

0201Still referring to <figref idref="DRAWINGS">FIG. 2C</figref>, once the client machine <b>10</b> is authenticated by the remote machine <b>30</b>, the remote machine prepares and transmits to the client machine <b>10</b> an HTML page <b>288</b> that includes a Resource Neighborhood window <b>258</b> in which appears graphical icons <b>257</b>, <b>257</b>′ representing resources to which the client machine <b>10</b> has access. A user of client machine <b>10</b> requests access to a resource represented by icon <b>257</b> by clicking that icon <b>257</b>.

0202<figref idref="DRAWINGS">FIG. 3A</figref> shows one embodiment of a process of communication among the client machine <b>10</b> and multiple remote machines <b>30</b>, <b>30</b>′. In the embodiment shown in <figref idref="DRAWINGS">FIG. 3A</figref>, the client machine <b>10</b> has an active connection <b>372</b> with the remote machine <b>30</b>′. The client machine <b>10</b> and remote machine <b>30</b>′ can use the active connection <b>372</b> to exchange information regarding the status or execution of a first resource. User credentials may be stored at the client machine <b>10</b>. Such storage of the user credentials can be in cache memory or persistent storage.

0203In this embodiment, the Resource Neighborhood application (not shown on <figref idref="DRAWINGS">FIG. 3A</figref>) runs on the client machine <b>10</b>. The client machine display has a Resource Neighborhood window <b>258</b> in which appears a graphical icon <b>257</b> representing a second resource. A user of the client machine <b>10</b> can access the second resource by double-clicking the icon <b>257</b> with the mouse. The request passes to the remote machine <b>30</b> via connection <b>359</b>. The remote machine <b>30</b> indicates to the client machine <b>10</b> via connection <b>359</b> that the sought-after resource is available on remote machine <b>30</b>′. The client machine <b>10</b> signals the remote machine <b>30</b>′ to establish a second connection <b>370</b>. The remote machine <b>30</b>′ requests the user credentials from the client machine <b>10</b> to authenticate access to the second resource. Upon a successful authentication, the client machine <b>10</b> and remote machine <b>30</b>′ establish the second connection <b>370</b> and exchange information regarding status of or execution of the second resource. In some embodiments, the remote machine does not request user credentials to establish the second connection <b>370</b>. In these embodiments, the remote machine <b>30</b>′ may use the credentials supplied by the user of client machine <b>10</b> to establish the connection <b>372</b> to also establish the second connection <b>370</b>. Accordingly, the client machine <b>10</b> and the remote machine <b>30</b>′ communicate with each other over multiple connections.

0204<figref idref="DRAWINGS">FIG. 3B</figref> shows one embodiment of a system of communication among the client machine <b>10</b>, master remote machine <b>30</b>, and servers <b>32</b>, <b>34</b>, and <b>36</b>. The client machine <b>10</b> has an active connection <b>373</b> with the remote machine <b>32</b>. The client machine <b>10</b> and remote machine <b>32</b> can use the active connection <b>373</b> to exchange information regarding the status of or execution of a first resource. User credentials may be stored at the remote machine <b>32</b> in cache memory or in persistent storage.

0205In this embodiment, the Resource Neighborhood application runs on the remote machine <b>32</b>. The remote machine <b>32</b> includes software providing a server-based client engine <b>62</b>, enabling the remote machine <b>32</b> to operate in the capacity of the client machine <b>10</b>. The client machine <b>10</b> display has a Resource Neighborhood window <b>258</b> in which appear graphical icons <b>357</b>, <b>357</b>′ representing a second resource and a third resource, respectively. A user of the client machine <b>10</b> can access the second resource by double-clicking the icon <b>357</b>. The request to launch the second resource passes to the remote machine <b>32</b> via active connection <b>373</b>, and the remote machine <b>32</b> forwards the request to the master remote machine <b>30</b> (arrow <b>365</b>).

0206The master remote machine <b>30</b> indicates (arrow <b>365</b>) to the remote machine <b>32</b> that the sought-after resource is available on server <b>34</b>. The remote machine <b>32</b> contacts the server <b>34</b> to establish a connection <b>366</b>. To authenticate access to the application, the server <b>34</b> obtains the user credentials of the client machine <b>10</b> from the remote machine <b>32</b>. The remote machine <b>32</b> and server <b>34</b> establish the connection (arrow <b>366</b>) by which the remote machine <b>32</b> requests access to the second resource and the server <b>34</b> returns the results to the remote machine <b>32</b>. The remote machine <b>32</b> forwards the results to the client machine <b>10</b>, where the results are displayed. Accordingly, the information exchanged between the client machine <b>10</b> and the server <b>34</b> “passes through” the remote machine <b>32</b>.

0207Similarly, the client machine <b>10</b> can launch the third resource by double-clicking the icon <b>357</b>′. The request to launch the third resource passes to the remote machine <b>32</b>. The remote machine <b>32</b> forwards the request to the master remote machine <b>30</b>. In this example, the master remote machine <b>30</b> indicates that the server <b>36</b> can be used to access the third resource.

0208The remote machine <b>32</b> and the server <b>36</b> establish a connection (arrow <b>374</b>) by which the remote machine <b>32</b> requests access to the third resource, and the server <b>36</b> returns the results to the remote machine <b>32</b>. To permit access to the third resource, the server <b>36</b> can authenticate the user credentials of the user of the client machine <b>10</b>, which are obtained from the remote machine <b>32</b>. The remote machine <b>32</b> forwards the results to the client machine <b>10</b> where the results are displayed. Accordingly, the results of accessing the third resource pass between the client machine <b>10</b> and the server <b>36</b> through the remote machine <b>32</b>.

0209<figref idref="DRAWINGS">FIG. 3C</figref> shows another embodiment of a system of communication among the client machine <b>10</b>, a master remote machine <b>30</b>, and servers <b>32</b> and <b>34</b>. The client machine <b>10</b> has an active connection <b>376</b> with server <b>32</b>. The client machine <b>10</b> and server <b>32</b> can use the active connection <b>376</b> to exchange information regarding the access to a first resource. The client machine <b>10</b> can store user credentials in cache memory or in persistent storage.

0210In this embodiment, the Resource Neighborhood application runs on the server <b>32</b>. The client machine <b>10</b> display has a Resource Neighborhood window <b>258</b> in which appears a graphical icon <b>257</b> representing a second resource. A user of the client machine <b>10</b> can access the second resource by double-clicking the icon <b>257</b>. The request to access the second resource passes to the server <b>32</b>. The server <b>32</b> responds (i.e., “calls back”) to the client machine <b>10</b> by returning resource-related information such as the name of the resource and capabilities needed by the client machine <b>10</b> to access the second application.

0211With the information provided by the server <b>32</b>, the client machine <b>10</b> then communicates with the master remote machine <b>30</b> via connection <b>377</b> to determine the server for accessing the second resource. In this example, that server is server <b>34</b>. The client machine <b>10</b> then establishes a connection <b>378</b> to the server <b>34</b>. Server <b>34</b> requests the user credentials from the client machine <b>10</b> to authenticate the user of the client machine <b>10</b>. The client machine <b>10</b> accesses the second resource on the server <b>34</b>, and the server <b>34</b> returns the results to the client machine <b>10</b> via the established connection <b>378</b>. Accordingly, the client machine <b>10</b> can have multiple active connections between the multiple servers.

0212<figref idref="DRAWINGS">FIG. 3D</figref> shows one embodiment of a system of communication between the client machine <b>10</b>, a remote machine <b>30</b> that in this example acts as a web server, and a second remote machine <b>30</b>′. The client machine <b>10</b> authenticates itself to the remote machine <b>30</b> as described above in connection with <figref idref="DRAWINGS">FIG. 2C</figref>. In one embodiment, the remote machine <b>30</b> accesses an output display template <b>390</b>, such as an SGML, HTML or XML file, to use as a base for constructing the Resource Neighborhood window to transmit to the client machine <b>10</b>. The Resource Neighborhood window may display an enumeration of resources available to the client. The enumeration of resources may include an enumeration of available application programs or computing environments. The template may be stored in volatile or persistent memory associated with the server <b>30</b> or it may be stored in mass memory <b>392</b>, such as a disk drive or optical device, as shown in <figref idref="DRAWINGS">FIG. 3D</figref>.

0213In this embodiment, the template <b>390</b> is a standard SGML, HTML, or XML document containing Resource Neighborhood-specific tags that are replaced with dynamic information. The tags indicate to the server <b>30</b> where in the output display to insert information corresponding to available resources, such as icon images. In one particular embodiment, the Resource Neighborhood-specific tags are embedded within comments inside a file, allowing the file to remain compatible with standard interpreters. In another embodiment, the Resource Neighborhood-specific tags are extensions of the markup language used as the base for the template.

0214Examples of HTML tags that may be used in a template are set forth below in Table 1:

0000<tables id="TABLE-US-00001" num="00001"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="1" colwidth="91pt" align="left" /><colspec colname="2" colwidth="126pt" align="left" /><thead><row><entry namest="1" nameend="2" rowsep="1">TABLE 1</entry></row><row><entry namest="1" nameend="2" align="center" rowsep="1" /></row><row><entry>Tag</entry><entry>Description</entry></row><row><entry namest="1" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry>ControlField field value</entry><entry>This tag is used to set the value of data</entry></row><row><entry /><entry>that either persists between Resource</entry></row><row><entry /><entry>Neighborhood web pages, is set by the</entry></row><row><entry /><entry>user, or is used to help in cross page</entry></row><row><entry /><entry>navigation, such as user name, domain,</entry></row><row><entry /><entry>password, template, and resource.</entry></row><row><entry>DrawResourceNeighborhood</entry><entry>This tag is used to draw a Resource</entry></row><row><entry /><entry>Neighborhood display at this location in</entry></row><row><entry /><entry>an output display.</entry></row><row><entry>ResourceName</entry><entry>This tag is replaced by the name of the</entry></row><row><entry /><entry>published resource in the current</entry></row><row><entry /><entry>context.</entry></row><row><entry>WindowType</entry><entry>This tag is replaced by the window type of</entry></row><row><entry /><entry>the published resource in the current</entry></row><row><entry /><entry>context.</entry></row><row><entry>WindowHeight</entry><entry>This tag is replaced by the window height</entry></row><row><entry /><entry>of the published resource in the current</entry></row><row><entry /><entry>context.</entry></row><row><entry>WindowWidth</entry><entry>This tag is replaced by the window width</entry></row><row><entry /><entry>of the published resource in the current</entry></row><row><entry /><entry>context.</entry></row><row><entry>WindowScale</entry><entry>This tag is replaced by the window scale</entry></row><row><entry /><entry>of the published resource in the current</entry></row><row><entry /><entry>context.</entry></row><row><entry>WindowColors</entry><entry>This tag is replaced by the color depth of</entry></row><row><entry /><entry>the published resource in the current</entry></row><row><entry /><entry>context.</entry></row><row><entry>SoundType</entry><entry>This tag is replaced by the sound setting</entry></row><row><entry /><entry>of the published resource in the current</entry></row><row><entry /><entry>context.</entry></row><row><entry>VideoType</entry><entry>This tag is replaced by the video setting</entry></row><row><entry /><entry>of the published resource in the current</entry></row><row><entry /><entry>context.</entry></row><row><entry>EncryptionLevel</entry><entry>This tag is replaced by the encryption</entry></row><row><entry /><entry>level of the published resource in the</entry></row><row><entry /><entry>current context.</entry></row><row><entry>Icon</entry><entry>This tag is replaced by the icon of the</entry></row><row><entry /><entry>published resource in the current</entry></row><row><entry /><entry>context.</entry></row><row><entry namest="1" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0215Other tags can be provided to set control fields and to provide conditional processing relating to the Resource Neighborhood application.

0216In one embodiment, the template is constructed dynamically using, for example, COLD FUSION, manufactured by Allaire Corp. of Cambridge, Mass. or ACTIVE SERVER PAGES manufactured by Microsoft Corporation of Redmond, Wash. Alternatively, the template may be static. The Resource Neighborhood application parses the template, replacing Resource Neighborhood-specific tags as noted above. Tags that are not Resource Neighborhood-specific are left in the file to be parsed by the browser program <b>80</b> executing on the client <b>10</b>.

0217In one embodiment, a template parser object is provided that accepts an HTML template as input, interprets Resource Neighborhood-specific tags present in the template, and outputs the original template with all Resource Neighborhood tags replaced with appropriate text. The template parser object can be passed a cookie, a URL query string, or a control field from a web server interface to provide the information with which Resource Neighborhood-specific tags should be replaced.

0218In some embodiments, a web server receives a request from the client machine <b>10</b> for an enumeration of available computing environments. In one of these embodiments, the web server executes an application to access data regarding the computing environments. In another of these embodiments, a page template is retrieved from a database. In still of these embodiments, a page is created, at the web server, describing a display of stored computing environment images available to the client machine <b>10</b> responsive to the collected information and the retrieved page template, and the created page is transmitted to the client machine <b>10</b>, indicating to the client machine <b>10</b> each computing environment available to the client machine <b>10</b>. In some embodiments, computing environment images may comprise virtual machine images, resource images, screenshots of suspended virtual machines, and other images selected by a user or administrator for presentation to the user. In yet another of these embodiments, an output display is created indicating each computing environment available to the client machine <b>10</b> and transmitting the created output display to the client machine <b>10</b>.

0219In some embodiments, an output display is created comprising a page constructed in a markup language, the output display indicating each computing environment available to the client system and transmitted to the client system.

0220In another embodiment, the Resource Neighborhood application allows scripts to access information via an application programming interface. Scripts may be written in, for example, VBScript or Jscript. In this embodiment, the scripting language is used to dynamically generate an output display using information returned by the application in response to queries posed by the script. Once the output display is generated, it is transmitted to client machine <b>10</b> for display by the browser program <b>80</b>.

0221A user of the client machine <b>10</b> can access a resource by clicking an icon <b>257</b>, <b>257</b>′ displayed in the Resource Neighborhood web page. In some embodiments, each icon <b>257</b>, <b>257</b>′ is associated with an encoded URL that specifies: the location of the resource (i.e., on which remote machines it is hosted or, alternatively, the address of a master remote machine, a gateway, or other remote machine <b>30</b>); a launch command associated with the resource; and a template identifying how the results of accessing the resource should be displayed (i.e., in a window “embedded” in the browser or in a separate window). In some embodiments, the URL includes a file, or a reference to a file, that contains the information necessary for the client to create a connection to the remote machine hosting the resource. This file may be created by the Resource Neighborhood application dynamically. The client machine <b>10</b> establishes a connection (arrow <b>394</b>) with the remote machine <b>30</b>′ identified as hosting the requested resource and exchanges information regarding access to the desired resource. In some embodiments, the connection <b>394</b> is made using the Independent Computing Architecture (ICA) protocol, manufactured by Citrix Systems, Inc. of Fort Lauderdale, Fla. In other embodiments, the connection is made using: the RDP protocol, manufactured by Microsoft Corp. of Redmond, Wash.; the X11 protocol; or the Virtual Network Computing (VNC) protocol, manufactured by AT&amp;T Bell Labs. Thus, the client machine <b>10</b> may display the results of accessing the resource in a window separate from the web browser <b>280</b>, or it may “embed” application output within the web browser.

0222<figref idref="DRAWINGS">FIG. 3E</figref> depicts an embodiment in which a remote machine <b>30</b> acts as an intermediary for a machine farm <b>38</b> and comprises a broker module <b>310</b>, a transmitter <b>312</b>, a receiver <b>314</b>, and a transceiver <b>316</b>.

0223The broker module <b>310</b> accesses collected data regarding resources, including application programs, computing environments, and hardware resources. In some embodiments, the broker module <b>310</b> accesses collected data regarding resources and determines for each resource whether that resource image is available to a client machine <b>10</b>. In some embodiments, the server further comprises a database storing the collected data. In one of these embodiments, the broker module <b>310</b> determines for each resource whether that resource image is available to a client machine <b>10</b> based on the collected data. In other embodiments, the broker module <b>310</b> receives user credentials and determines for each resource whether that resource image is available to a client machine <b>10</b> based on the user credentials and the collected data.

0224In some embodiments, the server further comprises an output display creation engine creating output displays indicating each resource available to the client machine <b>10</b>. In one of these environments, the output display creation engine creates a page describing a display of the resources available to a client system, the page created responsive to the collected information and a page template.

0225The transmitter <b>312</b> transmits accessed data to the client machine <b>10</b> indicating to the client machine <b>10</b> each resource determined to be available to the client machine <b>10</b>. In some embodiments, the transmitted data is displayable at the client system as icons in a graphical user interface window representing resources available to the client system. In other embodiments, the transmitted data is displayable at the client system as icons in a graphical user interface window representing resources unavailable to the client system. The receiver <b>314</b> receives a request to access one of the available resources. In some embodiments, the receiver receives user credentials from the client machine <b>10</b>. In other embodiments, the receiver receives a request to access an application program available through one of the available resources, such as an available computing environment. In still other embodiments, a database storing the collected information and the service module determines for each resource stored by the plurality of servers whether that resource image is available to a client machine <b>10</b> based on the user credentials and the collected information. In yet other embodiments, a determination is made as to an availability of resources, such as virtual machines or application servers, providing access to the available resources.

0226The transceiver <b>316</b> provides a connection between the client machine <b>10</b> and a virtual machine providing the requested resource. In some embodiments, the transceiver <b>316</b> provides a connection between the client machine <b>10</b> and a virtual machine providing the requested resource and the transceiver <b>316</b> establishes a presentation-layer protocol connection. In one of these embodiments, the transceiver <b>316</b> establishes an X11 or VNC connection. In another of these embodiments, the transceiver <b>316</b> establishes an ICA connection. In still another of these embodiments, the transceiver <b>316</b> establishes an RDP connection.

0227An intermediary machine of the sort just described may be used as any one of the remote machine <b>30</b> described above in <figref idref="DRAWINGS">FIGS. 1-1B</figref>, <b>2</b>A-<b>2</b>B, and <b>3</b>A-<b>3</b>D.

0228<figref idref="DRAWINGS">FIG. 4</figref> illustrates one embodiment of program components for a client-based implementation of the Resource Neighborhood application. A client-based implementation of the Resource Neighborhood application <b>416</b> can be used in a network using either the server-based computing model in which the servers execute the Resource Neighborhood application or in a client-based computing model in which the client machine <b>10</b> executes the Resource Neighborhood application locally. The Resource Neighborhood application includes a Resource Neighborhood Service (RNSVC) component <b>444</b>, a resource database component <b>448</b>, a Resource Neighborhood Application Program Interface (RNAPI) component <b>452</b>, a Resource Neighborhood User Interface component <b>456</b>, and a local cache <b>460</b>.

0229The remote machine <b>30</b>, for example, includes the service component (RNSVC) <b>444</b> and the resource authorization cache <b>448</b>. The client machine <b>10</b>, which is a representative example of a client machine <b>10</b> that can support a client-based implementation of the Resource Neighborhood application, includes the application program interface RNAPI <b>452</b>, the user interface user interface component <b>456</b>, and the local cache <b>460</b> components. The RNAPI <b>452</b> communicates with the user interface component <b>456</b> and the local cache <b>460</b>. The RNSVC <b>444</b> communicates with the resource authorization cache <b>448</b> and with the RNAPI <b>452</b> on the client machine <b>10</b> via communications link <b>462</b>.

0230The communications link <b>462</b> can be established by, for example, using the ICA protocol, the RDP protocol, the X11 protocol, the VNC protocol, or any other suitable presentation-level protocol designed to run over industry standard transport protocols, such as TCP/IP, IPX/SPX, NetBEUI, using industry-standard network protocols, such as ISDN, frame relay, and asynchronous transfer mode (ATM) and which provides for virtual channels, which are session-oriented transmission connections that can be used by application-layer code to issue commands for exchanging data. The communications link <b>462</b> may also be established by protocols that support RPC or RPC-equivalents such as SOAP and HTTP. The communications link <b>462</b> may also be a communications link <b>150</b> as described above. The virtual channel commands are designed to be closely integrated with the functions of client machines. The ICA protocol can support the Resource Neighborhood virtual channel.

0231The Resource Neighborhood virtual channel protocol can include four groups of commands:

0232(1) Initialization-related commands;

0233(2) Single authentication related commands that can be supported by each client machine wanting a copy of the user credentials;

0234(3) Resource data related commands for implementing the Resource Neighborhood user interface; and

0235(4) Resource launch callback-related commands for running the user interface on a remote machine.

0236The resource authorization cache <b>448</b> may be a cache of the authorized user and group information for all the public (i.e., published) resources in a machine farm <b>38</b> or in a group of trusted domains. Each remote machine in a machine farm <b>38</b> can maintain its own resource-related information in persistent storage and build up the resource authorization cache <b>448</b> in volatile storage. In another embodiment, all collected resource-related information in the resource authorization cache <b>448</b> can be stored in persistent storage and made accessible to each other server in the machine farm <b>38</b>. The resource authorization cache <b>448</b> can be implemented in a proprietary format (e.g., as a linked list in memory) or using Novell's Directory Services (NDS) or any directory service adhering to the X.500 standard defined by the International Telecommunication Union (ITU) for distributed electronic directories. The resource authorization cache <b>448</b> may be implemented as a standard relational database.

0237The resource authorization cache <b>448</b> includes a list of remote machines. Each remote machine in the list has an associated set of resources. Associated with each resource is resource-related information that can include the resource name, a list of remote machines, and client users that are authorized to use that resource. An overly-simplified example of the resource-related information maintained in the database is illustrated by the following Table 2. Users A and B are users of the client machines <b>10</b>, “n/a” indicates that a desired application program is hosted, but is not available to client machine users, and “-” indicates that the application program is not hosted.

0000<tables id="TABLE-US-00002" num="00002"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="1" colwidth="49pt" align="center" /><colspec colname="2" colwidth="42pt" align="center" /><colspec colname="3" colwidth="35pt" align="center" /><colspec colname="4" colwidth="56pt" align="center" /><colspec colname="5" colwidth="35pt" align="center" /><thead><row><entry namest="1" nameend="5" rowsep="1">TABLE 2</entry></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row><row><entry>Remote</entry><entry /><entry>Customer</entry><entry /><entry /></row><row><entry>Machine Name</entry><entry>SpreadSheet</entry><entry>Database</entry><entry>Word Processor</entry><entry>Calculator</entry></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry>Server 30</entry><entry>User A</entry><entry>User B</entry><entry>n/a</entry><entry>—</entry></row><row><entry>Server 32</entry><entry>User B</entry><entry>n/a</entry><entry>User A</entry><entry>—</entry></row><row><entry>Server 34</entry><entry>—</entry><entry>—</entry><entry>—</entry><entry>User A</entry></row><row><entry /><entry /><entry /><entry /><entry>User B</entry></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0238Table 2 shows: a list of servers <b>30</b>, <b>32</b>, <b>34</b>; applications hosted by the servers (Spreadsheet, Customer Database, Word Processor, and Calculator); and those users who are authorized to use the applications. For example, the server <b>30</b> hosts the Spreadsheet program, the Customer Database and the Word Processor. User A is authorized to use the Spreadsheet, User B is authorized to use the Customer Database, and no users are authorized to use the Word Processor. It is to be understood that other techniques can be used to indicate who is authorized to use a particular application. For example, the user information stored in the database can be used to indicate those users who are unauthorized to use a particular application rather than those who are authorized, or to indicate that multiple users may access a resource on a remote machine <b>30</b>, or to indicate that a predetermined group of users are authorized to access a particular resource. Although Table 2 depicts an embodiment in which the resources that are available are application programs, a similar technique may be used for computing environments and other resources.

0239To obtain the information that is stored in the resource authorization cache <b>448</b>, the remote machine <b>30</b> obtains the resource-related information from each other machine in the machine farm <b>38</b> regarding the resources on those remote machines, including control information that indicates which client users and remote machines are permitted to access each particular resource. The resource-related information maintained in the database may or may not persist across re-boots of the remote machine <b>30</b>.

0240Each remote machine <b>30</b> having the Resource Neighborhood application installed thereon executes the RNSVC software <b>444</b>. The RNSVC software <b>444</b>, operating on each remote machine <b>30</b> establishes a communication link (e.g. a named pipe) with at least one other and, in some embodiments, each other remote machine <b>30</b>. The remote machines <b>30</b> exchange resource-related information on the communications links. In another embodiment, the RNSVC software <b>444</b> collects the resource-related information from the other remote machine <b>30</b> in the machine farm <b>38</b> through remote registry calls (e.g., the service component <b>444</b> transmits a datagram to other remote machine <b>30</b> in the farm <b>38</b> requesting the resource-related information corresponding to the resources hosted by those remote machine <b>30</b>). In some embodiments the resource authorization cache is populated by system administrators of by programs and scripts communicating with remotes machines <b>30</b>. The RNSVC <b>444</b> software also maintains the relationships of groups and users to published resources in the resource authorization cache <b>448</b> and accesses the information when authenticating a client user. An administrator of the remote machine <b>30</b> can use a user interface to configure the RNSVC <b>444</b>.

0241Other functions of the RNSVC software <b>444</b> include implementing the services and functions requested by the RNAPI <b>452</b> and communicating with the RNAPI <b>452</b> on the client machine <b>10</b> using a Resource Neighborhood virtual channel driver (VCRN). The VCRN operates according to the Resource Neighborhood virtual channel protocol described.

0242The RNAPI <b>452</b> is a set of software functions or services that are used by the Resource Neighborhood application to perform various operations (e.g., open windows on a display screen, open files, and display message boxes). The RNAPI <b>452</b> provides a generic mechanism for accessing user interface elements (e.g., icons) produced by running the Resource Neighborhood application and objects in a legacy (i.e., predecessor or existing for some time) client user interface. When the client machine <b>10</b> accesses an available resource, the accessing mechanism can launch the resource on the remote machine <b>30</b>, if necessary (e.g., when the client machine <b>10</b> is unable to locally execute the application).

0243The RNAPI <b>452</b> provides all published resource information to the user interface component <b>456</b> for display on the screen <b>12</b> (<figref idref="DRAWINGS">FIG. 1</figref>) of the client machine <b>10</b>. The RNAPI <b>452</b> also manages machine farm <b>38</b> logons in a local database of logon credentials (e.g., passwords) for users of the client machine <b>10</b> to support the single authentication feature. Credentials may or may not be persistent across a reboot (power-off and on cycles) of the client machine <b>10</b>.

0244The RNAPI <b>452</b> provides automatic and manual management for Resource Neighborhood objects stored in the local cache <b>460</b>. The local cache <b>460</b> can either be refreshed manually by the user of the client machine <b>10</b>, or at a user-definable refresh rate, or by the server at any time during a connection. In a Windows implementation, the RNAPI <b>452</b> can build remote application file resource associations and manage the “Start” menu and desktop icons for resource object shortcuts.

0245The user interface module <b>456</b> interfaces the RNAPI <b>452</b> and can be a functional superset of an existing client user interface (e.g., Remote Resource Manager). The user interface module <b>456</b> accesses the information stored in the local cache <b>460</b> through the RNAPI <b>452</b> and visually presents that information to the user on the display screen <b>12</b> (<figref idref="DRAWINGS">FIG. 1</figref>) of the client machine <b>10</b>. The displayed information is a mixture of information generated by a user of the client machine <b>10</b> and information obtained by the Resource Neighborhood application. The user interface module <b>456</b> can also show the user all resources that the user is currently accessing and all active and disconnected sessions.

0246In a Windows-based embodiment, the user interface module <b>456</b> can present a variety of graphical components, such as windows and pull-down menus, to be displayed on the display screen <b>12</b> (<figref idref="DRAWINGS">FIG. 1</figref>). A display of a combination of such graphical user interface components is generally referred to as a “desktop.” A desktop produced by the user interface module <b>456</b> can include a Resource Neighborhood window displaying the neighborhood of resources available to the user of the client machine <b>10</b>. These resources may be a filtered combination of the published resources hosted by a machine farm <b>38</b>. The user interface module <b>456</b> can generate a Resource Neighborhood window for each machine farm <b>38</b> or merge the resources from different machine farms <b>38</b> under a single Resource Neighborhood window.

0247At a top level, the Resource Neighborhood window includes a folder for each machine farm <b>38</b>. Clicking on one of the folders produces a window containing a representation (e.g., an icon) of each hosted resource available to the user, e.g., see <figref idref="DRAWINGS">FIGS. 6A and 6B</figref>. The Resource Neighborhood window becomes the focal point for accessing published resources, and the user interface module <b>456</b> can be used to access resources and launch applications through the RNAPI <b>452</b>. For example, the user of the client machine <b>10</b> can use the mouse <b>18</b> (<figref idref="DRAWINGS">FIG. 1</figref>) to select one of the displayed icons and launch the associated resource.

0248A feature of a client-based implementation is that the user can browse the objects displayed in the Resource Neighborhood window although the client machine is offline, that is, the connection <b>462</b> is inactive. Also, a user of the client machine <b>10</b> can drag application objects and folders out of the Resource Neighborhood window and into other graphical components (e.g., other windows, folders, etc.) of the desktop.

0249<figref idref="DRAWINGS">FIG. 5</figref> shows one embodiment of the program components for a server-based implementation of the Resource Neighborhood application. The components include a Service (RNSVC) component <b>544</b>′, a Resource Database component <b>548</b>′, an Application Program Interface (RNAPI) component <b>552</b>′, a User Interface component <b>556</b>′ and a local cache <b>560</b>′. Each software component <b>544</b>′, <b>548</b>′, <b>552</b>′, <b>556</b>′, and <b>560</b>′ is installed on the application server <b>30</b>′. The software components for the server-based implementation correspond to the software components for the client-based implementation of <figref idref="DRAWINGS">FIG. 4</figref>. The functionality of each server-based software component is similar to the client-based counterpart, with differences or added capabilities described below. The RNSVC <b>544</b>′ communicates with the resource database <b>548</b>′ and with the RNAPI <b>552</b>′ using local procedure calls. The RNAPI <b>552</b>′ also communicates with the user interface module <b>556</b>′ and the local cache <b>560</b>′.

0250Similar to that described in <figref idref="DRAWINGS">FIG. 4</figref> for the client machine <b>10</b>, the client machine <b>10</b> logs on to the network <b>40</b> (<figref idref="DRAWINGS">FIG. 1</figref>), the server <b>30</b>′ develops and maintains a database containing the resource related information collected from the other machines in the machine farm <b>38</b>, and a communication link is established between the server <b>30</b>′ and the client machine <b>20</b>. The application server <b>30</b>′ may be in communication with the client machine <b>10</b> via an ICA connection <b>562</b>′.

0251To run the Resource Neighborhood application in a server-based implementation, the user of the client machine <b>10</b> connects to an initial desktop (at the server <b>30</b>′) and launches the Resource Neighborhood application from within that desktop environment. The connection to the initial desktop can occur automatically, e.g., via a logon script of the client machine <b>20</b>, via an entry in a Startup group, or by another centrally managed server specific mechanism. All remote application management and launching is accomplished through this initial desktop.

0252Similar to that described in <figref idref="DRAWINGS">FIG. 4</figref> for the server <b>30</b>, the server <b>30</b>′ uses the user credentials to determine those resources that the user of the client machine <b>10</b> is authorized to use. A Resource Neighborhood graphical window is returned to the client machine <b>10</b> and displayed on the client screen <b>22</b> (<figref idref="DRAWINGS">FIG. 1</figref>). This window can contain icons representing the available and, possibly, the unavailable resources that are in the Resource Neighborhood of the client machine <b>20</b>.

0253In one embodiment, the web-based Resource Neighborhood application includes a group of objects that manage various aspects of a resource. In one embodiment, the Resource Neighborhood application includes three primary object classes that “plug in” to a web server: a gateway object class; a credentials object class; and a resources object class. In some specific embodiments, the object classes are provided as JavaBeans. The three primary object classes facilitate: validation of user credentials into a server farm; generation of lists of published resources that a specified user may access; provisioning of detailed information about a specific published resource; and conversion of resource application information into a format compatible with the protocol over which connection will be made.

0254When provided as JavaBeans, the objects can be accessed in a number of different ways. For example, they may be compiled as COM objects and made available to the web server as ActiveX components. In another embodiment, the JavaBeans can be used in their native form, such as when the server uses Java Server Pages technology. In yet another embodiment, the JavaBeans can be instantiated and used directly in a Java Servlet. In still another embodiment, the remote machine <b>30</b> can instantiate the JavaBeans as COM objects directly.

0255A credentials object class manages information necessary to authenticate a user into a target machine farm <b>38</b>. A credentials object passes stored user credentials to other Resource Neighborhood objects. In some embodiments, the credentials object is an abstract class that cannot be instantiated and represents a user's credentials. Various class extensions may be provided to allow different authentication mechanisms to be used, including biometrics, smart cards, token-based authentication mechanisms such as challenge-response and time-based password generation, or others. For example, a “clear text credentials” extension may be provided that stores a user's name, domain, and password in plain text.

0256A gateway object class handles communications with a target machine farm <b>38</b>. In one embodiment, the gateway object class is provided as an abstract Java class that cannot be instantiated. A particular gateway object may retrieve resource information by communicating with a machine farm <b>38</b> using a particular protocol, reading cached resource information, a combination of these two methods, or other various methods.

0257As noted above, the gateway object class may cache information to minimize communication with a target machine farm <b>38</b>. Extensions to the gateway object may be provided to communicate with the machine farm <b>38</b> over specific protocols, such as HTTP. In one embodiment, an extension class is provided that allows the gateway object to communicate with the machine farm <b>38</b> via WINDOWS NT named pipes. The gateway object may provide an application programming interface hook that allows other Resource Neighborhood objects to query the object for application information.

0258A resources object class contains information about published resources and returns information about resources hosted by the machine farm <b>38</b> in order to create the Resource Neighborhood web page. The resources object class creates objects representing resources by retrieving information relating to the resources, either from an object created by the gateway object or directly from the machines in the machine farm <b>38</b>. A resources object acts as a container for certain properties of the resource, some settable and some not settable, such as: the name of the resource (not settable); the width of the client window, in pixels, for this resource (settable); the height of the client window, in pixels, for this resource (settable); the number of colors to use when connecting to the resource (settable); the severity of audio bandwidth restriction (settable); the level of encryption to use when connecting to the resource (settable); the level of video to use when connecting to this resource (settable); whether the resource should be placed on a client's start menu (settable); whether the resource should be placed on the client's desktop (settable); the identity of the Resource Neighborhood folder to which the resource belongs (settable); the description of the resource (settable); the source of the graphics icon file for the resource (settable); the type of window that should be used when connecting to the resource (not settable); and whether to override default parameters for the object.

0259<figref idref="DRAWINGS">FIG. 6A</figref> is a screenshot of one embodiment of Resource Neighborhood window <b>620</b> that can be displayed on the screen <b>12</b>, <b>22</b> (<figref idref="DRAWINGS">FIG. 1</figref>) of a client machine <b>10</b>, <b>10</b>′ after the Resource Neighborhood application has executed. The window <b>120</b> includes graphical icons <b>622</b>. Each icon <b>622</b> represents a resource that is hosted by one of the machines in a machine farm <b>38</b>. Each represented resource is available to the user of the client machine <b>10</b>. The user can select one of the resources using the mouse <b>18</b>, <b>28</b> or keyboard <b>14</b>, <b>24</b>.

0260<figref idref="DRAWINGS">FIG. 6B</figref> is a screenshot of another embodiment of a Resource Neighborhood window <b>624</b> that can be displayed on the screen <b>12</b>, <b>22</b> (<figref idref="DRAWINGS">FIG. 1</figref>) of a client machine <b>10</b>, <b>10</b>′ after the Resource Neighborhood application has executed. The window <b>624</b> includes graphical icons <b>626</b>, <b>628</b>. Each icon <b>626</b>, <b>628</b> represents a resource that is hosted by one of the machines in a machine farm <b>38</b>. Each resource represented by one of the icons <b>626</b> is available to the user of the client machine <b>10</b>. The user can select one of the resources using the mouse <b>18</b>, <b>28</b> or keyboard <b>14</b>, <b>24</b>. For web-based Resource Neighborhood environments, the screenshots of <figref idref="DRAWINGS">FIGS. 6A and 6B</figref> are similar, except that icons <b>622</b>, <b>626</b>, <b>628</b> are displayed within a browser window.

0261Each resource represented by one of the icons <b>628</b> is unavailable to the user of the client machine <b>10</b>, although such resources are present in the server farm. The unavailability of these resources can be noted on the display screen (e.g., “X”s can be drawn through the icons <b>628</b>). An attempt to access such a resource can trigger a message indicating that the user is not authorized to access the resource. Alternatively, the attempt may invoke a method allowing the user of the client machine <b>10</b> to request access to the resource.

0262In some embodiments, the resource comprises a computing environment. In one of these embodiments, a connection is established between the client machine <b>10</b> and a virtual machine hosting the requested computing environment. In one embodiment, a presentation layer protocol is used in establishing the connection between the client system and the virtual machine. In another embodiment, the X11 protocol is used in establishing the connection. In still another embodiment, the Remote Desktop Protocol (RDP) is used in establishing the connection. In yet another embodiment, the Independent Computing Architecture (ICA) protocol is used in establishing the connection.

0263In some embodiments, a connection is established between the client machine <b>10</b> and a physical machine, such as a traditional workstation or server, hosting the requested computing environment. In other embodiments, a connection is established between the client machine <b>10</b> and a hardware partition hosting the requested computing environment.

0264In some embodiments, an enumeration of a plurality of resources available to the client machine <b>10</b> is provided (step <b>204</b>) responsive to a determination by a policy engine regarding whether and how a client machine may access a resource. The policy engine may collect information about the client machine prior to making the determination. Referring now to <figref idref="DRAWINGS">FIG. 7A</figref>, one embodiment of a computer network is depicted which includes a client machine <b>10</b>, a machine farm <b>38</b>, a collection agent <b>704</b>, a policy engine <b>706</b>, a policy database <b>708</b>, and a resource server <b>30</b>′. In one embodiment, the policy engine <b>706</b> is a remote machine <b>30</b>. Although only one client machine <b>10</b>, collection agent <b>704</b>, policy engine <b>706</b>, machine farm <b>38</b>, and resource server <b>30</b>′ are depicted in the embodiment shown in <figref idref="DRAWINGS">FIG. 7A</figref>, it should be understood that the system may provide multiple ones of any or each of those components.

0265In brief overview, when the client machine <b>10</b> transmits the policy engine <b>706</b> a request <b>206</b> for a resource enumeration, the collection agent <b>704</b> communicates with the client machine <b>10</b>, retrieving information about the client machine <b>10</b>, and transmits the client machine information <b>712</b> to the policy engine <b>706</b>. The policy engine <b>706</b> makes an access control decision by applying a policy from the policy database <b>708</b> to the received information <b>712</b>.

0266In more detail, the client machine <b>710</b> transmits to the policy engine <b>706</b> a request <b>206</b> for resource enumeration. In one embodiment, the policy engine <b>706</b> resides on a resource server <b>30</b>′. In another embodiment, the policy engine <b>706</b> resides on a remote machine <b>30</b>. In still another embodiment, a resource server <b>30</b>′ receives the request <b>206</b> from the client machine <b>10</b> and transmits the request <b>206</b> to the policy engine <b>706</b>. In yet another embodiment, the client machine <b>10</b> transmits a request <b>206</b> for resource enumeration to an intermediate remote machine <b>30</b>′″ (not shown), which transmits the request <b>206</b> to the policy engine <b>706</b>.

0267In some embodiments, the client machine <b>10</b> transmits the request <b>206</b> over a network connection such as those described above. Upon receiving the request, the policy engine <b>706</b> initiates information gathering by the collection agent <b>704</b>. The collection agent <b>704</b> gathers information regarding the client machine <b>10</b> and transmits the information <b>712</b> to the policy engine <b>706</b>.

0268In some embodiments, the collection agent <b>704</b> gathers and transmits the information <b>712</b> over a network connection. In some embodiments, the collection agent <b>704</b> comprises bytecode, such as an application written in the bytecode programming language JAVA. In some embodiments, the collection agent <b>704</b> comprises at least one script. In those embodiments, the collection agent <b>704</b> gathers information by running at least one script on the client machine <b>10</b>. In some embodiments, the collection agent comprises an Active X control on the client machine <b>10</b>. An Active X control is a specialized Component Object Model (COM) object that implements a set of interfaces that enable it to look and act like a control.

0269In one embodiment, the policy engine <b>706</b> transmits the collection agent <b>704</b> to the client machine <b>10</b>. In some embodiments, the policy engine <b>706</b> requires another execution of the collection agent <b>704</b> after the collection agent <b>704</b> has transmitted information <b>712</b> to the policy engine <b>706</b>. In some of these embodiments, the policy engine <b>706</b> requires another execution of the collection agent <b>704</b> because the policy engine <b>706</b> may have insufficient information <b>712</b> to determine whether the client machine <b>10</b> satisfies a particular condition. In other embodiments, the policy engine <b>706</b> requires a plurality of executions of the collection agent <b>704</b> in response to received information <b>712</b>.

0270In some embodiments, the policy engine <b>706</b> transmits instructions to the collection agent <b>704</b> determining the type of information the collection agent <b>704</b> gathers from the client machine <b>10</b>. In those embodiments, a system administrator may configure the instructions transmitted to the collection agent <b>704</b> from the policy engine <b>706</b>. This provides greater control over the type of information collected. This also expands the types of access control decisions that the policy engine <b>706</b> can make, due to the greater control over the type of information collected. The collection agent <b>704</b> gathers information <b>712</b> including, without limitation, machine ID of the client machine <b>10</b>, operating system type, existence of a patch to an operating system, MAC addresses of installed network cards, a digital watermark on the client device, membership in an Active Directory, existence of a virus scanner, existence of a personal firewall, an HTTP header, browser type, device type, network connection information such as internet protocol address or range of addresses, machine ID of the remote machine <b>30</b>, date or time of access request including adjustments for varying time zones, and authorization credentials.

0271In some embodiments, the device type is a personal digital assistant. In other embodiments, the device type is a cellular telephone. In other embodiments, the device type is a laptop computer. In other embodiments, the device type is a desktop computer. In other embodiments, the device type is an Internet kiosk. In still other embodiments, the device type is a game console.

0272In some embodiments, the digital watermark includes data embedding. In some embodiments, the watermark comprises a pattern of data inserted into a file to provide source information about the file. In other embodiments, the watermark comprises hashed data files to provide tamper detection. In other embodiments, the watermark provides copyright information about the file.

0273In some embodiments, the network connection information pertains to bandwidth capabilities. In other embodiments, the network connection information pertains to the Internet Protocol address of the client machine <b>10</b>. In still other embodiments, the network connection information consists of the Internet Protocol address of the client machine <b>10</b>. In one embodiment, the network connection information comprises a network zone identifying the logon agent to which the client machine <b>10</b> provided authentication credentials.

0274In some embodiments, the authorization credentials include a number of types of authentication information, including without limitation, user names, client names, client addresses, passwords, Personal Identification Numbers (PINs), voice samples, one-time passcodes, biometric data, digital certificates, tickets, etc. and combinations thereof. After receiving the gathered information <b>712</b>, the policy engine <b>706</b> makes an access control decision based on the received information <b>712</b>.

0275Referring now to <figref idref="DRAWINGS">FIG. 7B</figref>, a block diagram depicts one embodiment of a policy engine <b>706</b>, including a first component <b>720</b>, including a condition database <b>722</b> and a logon agent <b>724</b>, and a second component <b>730</b>, including a policy database <b>732</b>. The first component <b>720</b> applies a condition from the condition database <b>722</b> to information <b>712</b> received about client machine <b>10</b> and determines whether the received information <b>712</b> satisfies the condition.

0276In some embodiments, a condition may require that the client machine <b>10</b> execute a particular operating system to satisfy the condition. In other embodiments, a condition may require that the client machine <b>10</b> execute a particular operating system patch to satisfy the condition. In still other embodiments, a condition may require that the client machine <b>10</b> provide a MAC address for each installed network card to satisfy the condition. In some embodiments, a condition may require that the client machine <b>10</b> indicate membership in a particular Active Directory to satisfy the condition. In another embodiment, a condition may require that the client machine <b>10</b> execute a virus scanner to satisfy the condition. In other embodiments, a condition may require that the client machine <b>10</b> execute a personal firewall to satisfy the condition. In some embodiments, a condition may require that the client machine <b>10</b> comprise a particular device type to satisfy the condition. In other embodiments, a condition may require that the client machine <b>10</b> establish a particular type of network connection to satisfy the condition.

0277If the received information satisfies a condition, the first component <b>720</b> stores an identifier for that condition in a data set <b>726</b>. In one embodiment, the received information satisfies a condition if the information makes the condition true. For example, a condition may require that a particular operating system be installed. If the client machine <b>10</b> has that operating system, the condition is true and satisfied. In another embodiment, the received information satisfies a condition if the information makes the condition false. For example, a condition may address whether spyware exists on the client machine <b>10</b>. If the client machine <b>10</b> does not contain spyware, the condition is false and satisfied.

0278In some embodiments, the logon agent <b>724</b> resides outside of the policy engine <b>706</b>. In other embodiments, the logon agent <b>724</b> resides on the policy engine <b>706</b>. In one embodiment, the first component <b>720</b> includes a logon agent <b>724</b>, which initiates the information gathering about client machine <b>10</b>. In some embodiments, the logon agent <b>724</b> further comprises a data store. In these embodiments, the data store includes the conditions for which the collection agent may gather information. This data store is distinct from the condition database <b>722</b>.

0279In some embodiments, the logon agent <b>724</b> initiates information gathering by executing the collection agent <b>704</b>. In other embodiments, the logon agent <b>724</b> initiates information gathering by transmitting the collection agent <b>704</b> to the client machine <b>10</b> for execution on the client machine <b>10</b>. In still other embodiments, the logon agent <b>724</b> initiates additional information gathering after receiving information <b>712</b>. In one embodiment, the logon agent <b>724</b> also receives the information <b>712</b>. In this embodiment, the logon agent <b>724</b> generates the data set <b>726</b> based upon the received information <b>712</b>. In some embodiments, the logon agent <b>724</b> generates the data set <b>726</b> by applying a condition from the database <b>722</b> to the information received from the collection agent <b>704</b>.

0280In another embodiment, the first component <b>720</b> includes a plurality of logon agents <b>724</b>. In this embodiment, at least one of the plurality of logon agents <b>724</b> resides on each network domain from which a client machine <b>10</b> may transmit a resource request <b>710</b>. In this embodiment, the client machine <b>10</b> transmits the resource request <b>710</b> to a particular logon agent <b>724</b>. In some embodiments, the logon agent <b>724</b> transmits to the policy engine <b>706</b> the network domain from which the client machine <b>10</b> accessed the logon agent <b>724</b>. In one embodiment, the network domain from which the client machine <b>10</b> accesses a logon agent <b>724</b> is referred to as the network zone of the client machine <b>10</b>.

0281The condition database <b>722</b> stores the conditions that the first component <b>720</b> applies to received information. The policy database <b>732</b> stores the policies that the second component <b>730</b> applies to the received data set <b>726</b>. In some embodiments, the condition database <b>722</b> and the policy database <b>732</b> store data in an ODBC-compliant database. For example, the condition database <b>722</b> and the policy database <b>732</b> may be provided as an ORACLE database, manufactured by Oracle Corporation of Redwood Shores, Calif. In other embodiments, the condition database <b>722</b> and the policy database <b>732</b> can be a Microsoft ACCESS database or a Microsoft SQL Server database, manufactured by Microsoft Corporation of Redmond, Wash.

0282After the first component <b>720</b> applies the received information to each condition in the condition database <b>722</b>, the first component transmits the data set <b>726</b> to second component <b>730</b>. In one embodiment, the first component <b>720</b> transmits only the data set <b>726</b> to the second component <b>730</b>. Therefore, in this embodiment, the second component <b>730</b> does not receive information <b>712</b>, only identifiers for satisfied conditions. The second component <b>730</b> receives the data set <b>726</b> and makes an access control decision by applying a policy from the policy database <b>732</b> based upon the conditions identified within data set <b>726</b>.

0283In one embodiment, policy database <b>732</b> stores the policies applied to the received information <b>712</b>. In one embodiment, the policies stored in the policy database <b>732</b> are specified at least in part by the system administrator. In another embodiment, a user specifies at least some of the policies stored in the policy database <b>732</b>. The user-specified policy or policies are stored as preferences. The policy database <b>732</b> can be stored in volatile or non-volatile memory or, for example, distributed through multiple servers.

0284Using the policy engine <b>706</b> as just described, an access control decision based upon information received about a client machine <b>10</b> is made. Upon receiving gathered information about the client machine <b>10</b>, the policy engine <b>706</b> generates a data set based upon the information. The data set contains identifiers for each condition satisfied by the received information <b>712</b>. The policy engine <b>706</b> applies a policy to each identified condition within the data set <b>726</b>. That application yields an enumeration of resources which the client machine <b>10</b> may access. In some embodiments, the enumeration of resources includes an enumeration of levels of access to the resource. In one of these embodiments, a plurality of allowable actions associated with the resource is enumerated. In another of these embodiments, a plurality of methods of execution of the resource is enumerated. The policy engine <b>706</b> then presents that enumeration to the client machine <b>10</b>. In some embodiments, as described above in connection with <figref idref="DRAWINGS">FIGS. 6A and 6B</figref>, the policy engine <b>706</b> creates a Hypertext Markup Language (HTML) document used to present the enumeration to the client machine.

0285In some embodiments, the policy engine <b>706</b> transmits the enumeration to a different remote machine <b>30</b>. In one of these embodiments, the remote machine <b>30</b> transmits the enumeration to the client machine <b>10</b>. In another of these embodiments, the remote machine <b>30</b> applies additional policies to the enumeration. In still another of these embodiments, the remote machine is an appliance such as an application gateway or a firewall. In some of these embodiments, the policy engine <b>706</b> transmits an assigned level of action applicable to a requested resource to a remote machine <b>30</b> functioning as a broker server. The broker server establishes, responsive to the assigned level of access, a connection between the client machine <b>10</b> and a computing environment providing the requested resource.

0286Referring now to <figref idref="DRAWINGS">FIG. 8</figref>, a flow diagram depicts one embodiment of the steps taken to provide access to a resource. In brief overview, a request for access to a resource is received (step <b>802</b>). A method for providing access to the resource is identified (step <b>804</b>). An application execution server may be selected to provide access to the resource (step <b>806</b>). A virtualized environment may be selected to provide access to a resource (step <b>808</b>). An application streaming service may be selected to provide access to the resource (step <b>816</b>). If the virtualized environment is selected to provide access to the resource, an execution machine is identified (step <b>810</b>). A virtual machine is selected (step <b>812</b>). The virtual machine is configured (step <b>814</b>). Access to the resource is provided (step <b>818</b>).

0287Still referring to <figref idref="DRAWINGS">FIG. 8</figref>, and in more detail, a request for access to a resource is received (step <b>802</b>). In one embodiment, a remote machine <b>30</b> receives the request. In some embodiments, the remote machine <b>30</b> is an intermediate broker server. In other embodiments, the remote machine <b>30</b> is a gateway. In still other embodiments, the remote machine <b>30</b> is a policy engine. In yet other embodiments, the remote machine <b>30</b> is an appliance.

0288In one embodiment, the remote machine <b>30</b> verifies that the user is authorized to access the resource. In still another embodiment, the remote machine <b>30</b> receives with the request information verifying authorization for access by the user.

0289In one embodiment, the remote machine <b>30</b> receives a request for an application program. In another embodiment, the remote machine <b>30</b> receives a request for access to a file. In yet other embodiments, the remote machine <b>30</b> receives a request for access to a computing environment. In one of these embodiments, the computing environment is a desktop environment from which the client machine <b>10</b> may execute application programs. In another of these embodiments, the computing environment provides access to one or more application programs. In some embodiments, the remote machine <b>30</b> receives a request for access to a computing environment supported by a plurality of hardware requirements. In some embodiments, a remote machine <b>30</b> functioning as deployment system receives a request for access to a resource, such as execution of an application program, from a client machine <b>10</b>.

0290A method for providing access to the resource is identified (step <b>804</b>). In one embodiment, a remote machine <b>30</b> consults a database to identify the method for providing access. In another embodiment, a remote machine <b>30</b> consults a policy or rules database to identify the method for providing access. In still another embodiment, a remote machine <b>30</b> receives from a policy engine an identification of a method to select.

0291For embodiments in which the resource is an application program, a policy may allow execution of the application program on the client machine <b>10</b>. In another of these embodiments, a policy may enable the client machine <b>10</b> to receive a stream of files comprising the application program. In this embodiment, the stream of files may be stored and executed in an isolation environment on the client. In still another of these embodiments, a policy may allow execution of the application program only on a remote machine, such as an application server, and require the remote machine to transmit application-output data to the client machine <b>10</b>. In yet another of these embodiments, a policy may allow execution of the application program only in a computing environment hosted on a virtual machine. In either of these cases, a stream of files comprising the application programs may be sent to the remote machine.

0292For embodiments in which the resource is a computing environment, a policy may allow installation of the computing environment on the client machine <b>10</b>. In another of these embodiments, a policy may enable the client machine <b>10</b> to access a copy of the computing environment executing in a virtual machine on a remote machine <b>30</b>. In still another of these embodiments, a policy may forbid the user of the client machine <b>10</b> to access the requested computing environment and offer an alternative computing environment.

0293For embodiments in which the resource is a computing environment supported by a plurality of hardware resources, a policy may enable the client machine <b>10</b> to access a copy of the computing environment executing in a virtual machine, which in turn executes on a hypervisor providing access to the requested plurality of hardware resources. In still another of these embodiments, a policy may forbid the user of the client machine <b>10</b> to access the requested computing environment and offer a computing environment supported by an alternative plurality of hardware resources.

0294The remote machine <b>30</b> may choose to provide access to an application execution server which provides access to a requested application program (step <b>806</b>). The application execution server executes the application program and transmits application output data to the client machine <b>10</b>. The application execution server may transmit the application output data over a presentation layer protocol, such as X11, VNC, ICA, or RDP.

0295Referring back to step <b>804</b>, the remote machine <b>30</b> may choose to provide access to an application streaming service capable of transmitting a requested application program to the client machine <b>10</b> (step <b>816</b>) for execution. Embodiments of application streaming services are described in greater detail below.

0296Referring back to step <b>804</b>, the remote machine <b>30</b> may choose to respond to the client's request by allowing access to a computing environment provided by a virtual machine, the computing environment providing access to the requested resource (step <b>808</b>). The computing environment may be provided by a virtual machine launched into a hypervisor executing on a remote machine <b>30</b>′. In other embodiments, the remote machine <b>30</b> determines to provision on the client machine <b>10</b> a virtual machine providing access to the computing environment.

0297In embodiments where a remote machine <b>30</b> determines to provide access to the requested resource via a virtualized environment, the remote machine <b>30</b> identifies an execution machine providing access to a computing environment requested by the client machine <b>10</b> (step <b>810</b>). In one of these embodiments, the remote machine <b>30</b> identifies an execution machine capable of hosting the computing environment. In another of these embodiments, the remote machine <b>30</b> determines that the user requesting access to the computing environment lacks authorization to access the requested computing environment. The remote machine <b>30</b> may identify an alternative computing environment which the user is authorized to access. In still another of these embodiments, the remote machine <b>30</b> identifies an execution machine on which a hypervisor provides access to a requested plurality of hardware and in which the requested computing environment may execute.

0298In other embodiments, the remote machine <b>30</b> is an execution machine capable of hosting the computing environment. In some of these embodiments, the computing environment is installed on the execution machine. In others of these embodiments, a hypervisor on the execution machine emulates a plurality of hardware resources required by the requested computing environment and the computing environment is launched in the hypervisor.

0299In some embodiments, the remote machine <b>30</b> identifies a remote machine <b>30</b>′ functioning as an execution machine capable of providing access to the computing environment supported by a requested plurality of hardware resources. In one of these embodiments, the remote machine <b>30</b>′ functions as an execution machine on which a hypervisor emulating the requested plurality of hardware resources executes and on which a computing environment supported by the hypervisor executes.

0300In some embodiments, an execution machine providing hardware resources, physical or virtual, capable of supporting a particular virtual machine is identified responsive to a load-balancing determination. In one of these embodiments, the execution machine is selected responsive to load-balancing information maintained by a management server <b>30</b>. In some embodiments, the management server <b>30</b> is a single machine. In still other embodiments, several remote machines <b>30</b> may be capable of acting as a management server, but only one of such nodes is designated the management server. In some embodiments, a client request is directed to the management server <b>30</b> in the first instance. In other embodiments, a remote machine <b>30</b> queries the management server <b>30</b> to determine the identity of a suitable execution machine.

0301The master network information server node <b>30</b> maintains a table of addresses for the remote machines <b>30</b>′, <b>30</b>″. In addition, the master network information server node <b>30</b> receives messages from the remote machines <b>30</b>′, <b>30</b>″ indicating their level of activity, which may comprise CPU load or may comprise an identification of the number of a virtual machines currently hosted by a remote machine <b>30</b>′, <b>30</b>″. The level of activity of the remote machines <b>30</b>′, <b>30</b>″ is maintained in a table along with the address of each of the remote machines <b>30</b>′, <b>30</b>″.

0302For embodiments, in which a single management server <b>30</b> is used, it is desirable to dynamically select a master network information server node <b>30</b> from the available remote machines <b>30</b> on the network. In this way, if the active management server <b>30</b> fails, a new management server <b>30</b> may be selected as soon as the failure of the previous management server <b>30</b> is detected. In one embodiment a management server <b>30</b> is selected by an election process among the remote machines <b>30</b>.

0303In one embodiment, any machine (client machine <b>10</b> or remote machine <b>30</b>) may force an election at any time by broadcasting a request election datagram to the machine farm <b>38</b>. The election results are determined by a comparison of the set of election criteria which is transmitted within the request election datagram transmitted by the requesting node with the set of election criteria maintained on each receiving node. That is, the first election criterion from the datagram of the requesting node is compared by the receiving node to the first criterion of the receiving node. The highest ranking of the two criteria being compared wins the comparison and the node with that criterion wins the election. If the two criteria tie, then the next criteria are sequentially compared until the tie is broken. If a remote machine <b>30</b> receiving the request election datagram has a higher election criterion than that received in the request election datagram, the remote machine <b>30</b> receiving the request election datagram issues its own request election datagram. If the receiving remote machine <b>30</b> has a lower election criteria than the criteria received in the request election datagram, the receiving remote machine <b>30</b> determines it is not the master network information server node and attempts to determine which remote machine <b>30</b> in the machine farm <b>38</b> is the management server <b>30</b>.

0304In one embodiment the criteria which determine the outcome of the election include: whether or not the node is statically configured as a master network information server node; whether the remote machine <b>30</b> has the higher master network information server software version number; whether the remote machine <b>30</b> is an NT domain controller; whether the remote machine <b>30</b> is the longest running node; and whether the remote machine <b>30</b> has a lexically lower network name. In one embodiment, the datagram structure for the election request includes an unsigned shortword for the server version number, an unsigned shortword in which the bits are flags which designate whether the node is statically configured as a master network information server node, or is executing on a NT domain controller and an unsigned longword containing the amount of time the server has been running.

0305Periodically, the management server <b>30</b> transmits a declare message to the other remote machines <b>30</b> declaring itself to be the management server <b>30</b>. If another remote machine <b>30</b> believes itself to be a management server <b>30</b>, the other remote machine <b>30</b> will request an election. In this way erroneous master network information server nodes <b>30</b> of the same protocol are detected and removed. In addition an election will also be requested: by any remote machine <b>30</b> when that remote machine <b>30</b> reboots; by any remote machine <b>30</b> to whom the master network information server node has failed to acknowledge an update message; or any client machine <b>10</b> to whom the master network information server node <b>30</b> has failed to respond to a request for information.

0306In more detail and referring to <figref idref="DRAWINGS">FIG. 9</figref>, once any remote machine <b>30</b> (which may be referred to as a node) broadcasts a request election datagram requesting an election (Step <b>920</b>), the remote machine <b>30</b> receiving the request election datagram (Step <b>924</b>) first compares its election criteria to the criteria in the request election datagram (Step <b>930</b>) to determine if the receiving remote machine <b>30</b> has higher criteria (Step <b>934</b>). If the remote machine <b>30</b> receiving the datagram has lower election criteria (Step <b>938</b>) than the criteria contained in the request election datagram, the remote machine <b>30</b> receiving the request election datagram drops out of the election process and awaits the results of the election (Step <b>938</b>).

0307If the remote machine <b>30</b> receiving the request election datagram has higher election criteria than that contained in the request election datagram, then the remote machine <b>30</b> receiving the request election datagram broadcasts its own request election datagram containing the remote machine's own election criteria (Step <b>940</b>). If in response to the transmission of the request election datagram by the second remote machine <b>30</b>, another remote machine <b>30</b>′ responds with a request election datagram with even higher election criteria, then the second remote machine <b>30</b> drops out of the election and the remote machine <b>30</b>′ with higher criteria broadcasts it's own request election datagram. If no other remote machine <b>30</b> responds with higher election criteria, the node which has apparently won the election for master network information server node sends n more election requests, (in one embodiment three requests) (Step <b>956</b>) and then if still no other remote machine <b>30</b> responds with higher election criteria, the remote machine <b>30</b> which has sent the n election requests is the new management server <b>30</b>.

0308After the election has occurred and the new management server <b>30</b> has been determined, all the remote machines <b>30</b> send all of their configured gateway addresses to the new network information server node <b>30</b>. In this way the new management server <b>30</b> becomes a gateway node.

0309Referring again to <figref idref="DRAWINGS">FIG. 1</figref>, once the management server <b>30</b> is elected, the remote machines <b>30</b> send update datagrams to the master network information server <b>30</b> providing information about each remote machine <b>30</b> transmitting the update datagram. In one embodiment, the update datagram sent to the master network information server node <b>30</b> from a remote machine <b>30</b> includes: the remote machine <b>30</b> name; the network address; the cluster name; the network transport protocol; the total number of remote machines <b>30</b> configured with this transport; the number of ports available for connection with a client using this transport protocol; the total number of users permitted to be active at one time; number of available user slots; and server load level. Upon receipt of the update datagram, the master network information server node <b>30</b> returns an acknowledgment to the remote machines <b>30</b> that transmitted the update datagram indicating that the update datagram was received. If the remote machine <b>30</b> transmitting the update datagram does not receive an acknowledgment from the master network information server node <b>30</b>, the transmitting remote machine <b>30</b> assumes that the master network information server node <b>30</b> has failed and transmits an election request.

0310In more detail and referring to <figref idref="DRAWINGS">FIG. 10</figref>, a remote machine <b>30</b>, after the election of a management server <b>30</b>, waits a random period of time and then sends a datagram to the management server <b>30</b> with its latest load information (Step <b>1000</b>). In one embodiment the delay is between four and six seconds. If the management server <b>30</b> receives (Step <b>1008</b>) an update datagram from a remote machine <b>30</b>, then the master network information server node <b>30</b> replies to the transmitting remote machine <b>30</b> with an acknowledgment (Step <b>1010</b>) and forwards the data to any remote machine <b>30</b> configured as a gateway node. If the master network information server <b>30</b> fails to receive data from a remote machine <b>30</b> (Step <b>1008</b>), then the master network information server <b>30</b> discards the old data from the remote machine <b>30</b> after a predetermined amount of time (Step <b>1020</b>).

0311If the remote machine <b>30</b> does not receive an acknowledgment from the master network information server node <b>30</b> after the remote machine <b>30</b> has sent an update datagram (Step <b>1028</b>), the remote machine <b>30</b> retransmits the update datagram. The remote machine <b>30</b> will attempt n retransmits (in one embodiment three) before it assumes that the master network information server <b>30</b> has failed and then transmits an election request (Step <b>1030</b>). If the remote machine <b>30</b> receives an acknowledgment, then it periodically updates the master network information server node <b>30</b>, in one embodiment every 5 to 60 minutes (Step <b>1040</b>).

0312In some embodiments, a remote machine's participation in the activities just described is controlled by a virtual machine executing in the hypervisor rather than by an operating system. <figref idref="DRAWINGS">FIG. 11</figref> is a block diagram depicting one embodiment of a machine farm <b>38</b> including a first and second network management processes. The first network management process <b>1110</b> executes in a native operating system <b>1105</b> (such as WINDOWS NT) and accesses a native memory element storing (i) a data table and (ii) at least one election criteria for allowing the first network management process <b>1110</b> to be dynamically selected as a management process, the data table having an entry for each of said at least two network management processes. The second network management process <b>1120</b> executes in a virtualized operating system <b>1115</b> and accesses a virtualized memory element storing (i) a data table and (ii) at least one election criteria for allowing the second network management process <b>1120</b> to be dynamically selected as the management process, the data table having an entry for each of said at least two network management processes. The client machine <b>10</b> communicates with the one of the first network management process <b>1110</b> and the second network management process <b>1120</b> selected as the management process and receives from the management process an address of a remote machine <b>30</b> with which to communicate. In some embodiments, a plurality of client machines <b>10</b> is in communication with a master network information process.

0313The first network management process <b>1110</b> executes in a native operating system <b>1105</b>. The second network management process <b>1120</b> executes in a virtualized operating system <b>1115</b>. In one embodiment, the at least two network management processes are grouped into clusters. In another embodiment, one of the at least two network processes is a gateway process. In still another embodiment, the gateway process is a master network management process. In some embodiments, the master network management process is selected by a process comprising the steps of (a) broadcasting an election datagram to the at least two network management processes, the election datagram comprising election criteria; and (b) selecting a master network management process in response to the election criteria. In one of these embodiments, the master network management process broadcasts a declare datagram to detect multiple master network management processes using the same transport protocol. In another of these embodiments, the master network management process is selected by a process that occurs after an event selected from the group of events consisting of: a system reboot, a master network management process failing to respond to a datagram sent from a network management process, a master network management process failing to respond to a request from a client machine, detection of at least two master network management processes configured with the same transport, and a new network management process appearing on said network.

0314In one embodiment, the management process is elected as described above in connection with <figref idref="DRAWINGS">FIGS. 9 and 10</figref>.

0315In some embodiments, the network includes a third network management process using a different network transport protocol from the first network management process. In one of these embodiments, the third network management process comprises a master network management process for the different network transport protocol.

0316For embodiments in which machine farm management is decentralized, each remote machine <b>30</b> may include a load management subsystem (LMS) providing a load management capability. In general, the LMS manages overall server and network load to minimize response time to client requests.

0317In some embodiments, an apparatus for selecting a server from a network plurality of servers to service a client request comprises a plurality of network management processes. In one of these embodiments, each of said plurality of network management processes includes an event bus and a subsystem in communication with the event bus. In another of these embodiments, a first one of the plurality of network management processes receives from a client machine a request for access to a computing resource and sends the client request to a second one of the plurality of network management processes. In still another of these embodiments, the second one of the plurality of network management processes executes in a virtualized operating system and comprises a dynamic store and a load management subsystem.

0318The dynamic store loads information associated with at least some of the plurality of network management processes in a virtualized memory element. In some embodiments, the dynamic store contains information relating to server processor load. In other embodiments, the dynamic store contains information relating to server input/output transaction load.

0319The load management subsystem (i) receives, via said event bus, a request to identify a server for servicing a client request, (ii) retrieves from said dynamic store the loading information, (iii) chooses, based on the retrieved loading information, one of the plurality of servers for servicing the client request, and (iv) transmits, via said event bus, a message including information identifying the chosen server. In some embodiments, the load management subsystem stores run-time information in the dynamic store at predetermined intervals. In other embodiments, the apparatus further includes a persistent store, the load management subsystem in communication with the persistent store via the event bus, the persistent store containing an identification of at least one rule to be used to manage server load.

0320In one embodiment, the LMS is rule-based, and an administration tool can be used to modify or create rules for managing server load. A rule is one or more criteria that influences how a LMS will direct requests. Rules may be individualized to a specific remote machine <b>30</b>. Rules can also be individualized to a specific application or computing environment on a per-server basis. That is, one or more rules may be associated with a copy of an application or a computing environment residing on a first remote machine <b>30</b> in the machine farm <b>38</b> and different rules may be associated with a copy of the same application or computing environment residing on a second remote machine <b>30</b> in a machine farm <b>38</b>. The output of rules individualized to a specific application may be combined with the output of general server rules to direct a client request.

0321Rules use the output from one or more operational meters. Operational meters may measure any aspect of server performance and the result is used by rules to help determine which remote machine <b>30</b> is most appropriate to service a client request. For example, operational meters may measure: processor load; context switches; memory usage; page faults; page swaps; transmission rate of input/output reads or writes; number of input/output operations performed or number of virtual machines hosted. In one embodiment, operational meters are used by a LMS to measure server performance during the occurrence of certain events such as a request for a client connection. In another embodiment, operational meters are used by a LMS to measure server performance at predetermined intervals, which may be configured by an administrator. A LMS on each remote machine <b>30</b> in the machine farm <b>38</b> evaluates various performance metrics for the remote machine <b>30</b> for each predetermined period of time and stores that information in the dynamic store. For example, every thirty seconds, an evaluation of server load may include a query to operational meters for server's CPU utilization and memory utilization. The results from the query will be used, in conjunction with other applicable load factors, to calculate a load number for this server load. The new load number is then sent to the dynamic store.

0322Rules and operational meters are, in one embodiment, executable code modules that query specific system conditions, resources, and performance metrics for remote machines <b>30</b> in the machine farm <b>38</b>. Some of the rules accept user-configurable parameters that are entered by the administrator via the administration tool. Rules may be provided to the LMS using a dynamic link library (“DLL”), and the rules and rule parameters applicable to a specific server may be stored in the persistent store. That is, the administrator's selection of rules is stored, together with a weighting factor and applicable settings associated with those rules, in the persistent store. For example, some operational meters may measure load at a predetermined interval; the predetermined interval may be set by the administrator.

0323Examples of conditional rules that may be used by the LMS to determine to which remote machine <b>30</b> to direct a request include: whether the number of client machines <b>10</b> that may connect to a remote machine <b>30</b> is limited; whether the number of client sessions that may be serviced by a remote machine <b>30</b> is limited; whether the number of virtual machines that may be hosted by a remote machine <b>30</b> is limited; the number of application or connection licenses available to a remote machine <b>30</b>; whether the application requested by the client machine <b>10</b> is currently executing on the remote machine <b>30</b>; whether a client is physically proximate to, or is connected by a high bandwidth link to, a server; and whether a client request is being made during a time period for which the remote machine <b>30</b> is available to service client requests.

0324A set of rules may be grouped together by the group subsystem <b>300</b> to form a load evaluator associated with a particular server or a particular application. A server load evaluator is a load evaluator that applies to all applications published on the server. An application load evaluator is a load evaluator that encapsulates rules specific to certain applications. In one embodiment, loads for published application programs are the sum of a server load evaluator and an application load evaluator. The load evaluator associated with a particular server may be stored in the persistent store <b>230</b>. When a LMS initializes, it queries persistent store <b>230</b> to determine whether a load evaluator is associated with the remote machine <b>30</b> on which the LMS resides. If so, the rules and operational meters are loaded and the LMS begins using those elements of the load evaluator. The outputs of the constituent parts of the load evaluator are combined to calculate composite indicia of the load on particular servers, and each LMS stores the results of its load evaluator in dynamic store. Each rule encapsulated in a load evaluator may have a configurable weighting factor. Many rules have user-configurable parameters that control the way LMS loads are calculated. For example, in one embodiment, a CPU Utilization rule has two parameters: Report Full Load when processor utilization is greater than X-percent; report no load when processor utilization is less than X percent. In one particular embodiment, the load reported by a load evaluator equals the sum of each rule's load times each rule's weight.

0325In another example, a remote machine <b>30</b> that hosts four applications may have three load evaluators with which it is associated. The server itself and a first application may by associated with a first load evaluator, the second and third applications may be associated with a second load evaluator, and the fourth application may be associated with a third load evaluator. When the remote machine <b>30</b> boots, it read the first, second, and third load evaluators from the persistent store <b>230</b>. Periodically (or perhaps after certain events) the remote machine <b>30</b> calculates the output for each of the load evaluators and sends those values to the dynamic store. When a connection request is received, those values are used to determine if the remote machine <b>30</b> should service a client request.

0326For example, using operational meters the LMS can obtain information about the processor load on a particular remote machine <b>30</b>, the memory load on that remote machine <b>30</b>, and the network load of that remote machine <b>30</b>. The LMS combines these results to obtain an overall load number that indicates the total aggregate load on that remote machine <b>30</b>. In determining the aggregate load, the load evaluator may weight each piece of information differently. For embodiments in which a rule is associated with a remote machine <b>30</b>, the rule may disqualify a remote machine <b>30</b> from servicing a client request. For example, a rule may limit the number of client sessions a remote machine <b>30</b> may initiate. In this embodiment, if a remote machine <b>30</b> is currently servicing the maximum number of client sessions allowed by the rule, it will not be chosen by the LMS to service a new client request, even if the outputs of its operational meters indicate that it is the most favorable remote machine <b>30</b> to which to route the client request.

0327Referring back to <figref idref="DRAWINGS">FIG. 8</figref>, after an execution machine has been selected, a virtual machine providing a requested computing environment is identified (step <b>812</b>). In some embodiments, declarative policies such as rules databases, policy databases or scripts are consulted to direct requests to a virtual machine. In other embodiments, a remote machine <b>30</b> functioning as an application server hosting a plurality of virtual machines is identified. In one of these embodiments, one of the plurality of virtual machines hosted by the application server may be selected and associated with the client machine <b>10</b>. In another of these embodiments, an identifier for the selected virtual machine may be transmitted to the client machine <b>10</b>.

0328In some embodiments, a session management component identifies the virtual machine. In one of these embodiments, an intermediate machine <b>30</b> receiving the request invokes a session management component. In another of these embodiments, the intermediate machine launches the session management component in a terminal services session executing on the intermediate machine. In still another of these embodiments, the intermediate machine launches the session management component in a terminal services session executing on the identified execution machine.

0329In one embodiment, the session management component provides functionality for identifying a location of a virtual machine providing access to a computing environment. In still another embodiment, the session management component is provided as a program module published on a server, such as an application server. In yet another embodiment, the session management component identifies, launches, and monitors virtual machines.

0330In some embodiments, the session management component communicates with a virtual machine management component to identify a virtual machine. In one of these embodiments, the virtual machine management component provides functionality for locating virtual machines. In another of these embodiments, the virtual machine management component provides functionality for allocating an available virtual machine to a user from a plurality of available virtual machines. In still another embodiment, the virtual machine management component provides functionality for reallocating shared virtual machines to the plurality of available virtual machines. In yet another embodiment, the virtual machine management component provides functionality for tracking a state associated with a virtual machine for each virtual machine in a plurality of virtual machines.

0331Referring now to <figref idref="DRAWINGS">FIG. 12</figref>, a block diagram depicts one embodiment of a virtual machine management component <b>1200</b>. In one embodiment, the virtual machine management component <b>1200</b> provides functionality for accessing and updating a database including a virtual machine catalog. In another embodiment, the virtual machine management component <b>1200</b> provides functionality for allowing an administrator or virtual machine provisioning system to add, remove, or modify entries in the database including a virtual machine catalog. In some embodiments, the virtual machine management component <b>1200</b> includes a virtual machine providing administrative functionality. In other embodiments, the virtual machine component <b>1200</b> includes a virtual machine providing management functionality.

0332In some embodiments, the virtual machine management component <b>1200</b> may receive a request from a provisioning system or from a session management component. In one of these embodiments, a provisioning system contacts the virtual machine management component <b>1200</b> when a virtual machine is created or destroyed. In another of these embodiments, the session management component contacts the virtual machine management component <b>1200</b> when the session management component is invoked to request a virtual machine to launch. In still another of these embodiments, the session management component contacts the virtual machine management component <b>1200</b> when the session management component identifies a change in a state of a launched virtual machine. The session management component may send messages, such as heartbeat messages, to the virtual machine management component <b>1200</b> while a virtual machine is active. If the virtual machine may be accessed by more than one user, the virtual machine management component <b>1200</b> may reassign the virtual machine to the plurality of available virtual machines after a user has terminated a session with the virtual machine.

0333In some embodiments, virtual machines of the same machine type may be categorized into a plurality of standard operating environments (SOE). In one of these embodiments, an SOE may be a group of virtual machine images of a particular configuration that implement the function of a particular Machine Type, e.g. a machine type “C++ Developer Workstation” may have one SOE containing images with WinXP Pro SP2 with Visual Studio 2003 installed and another SOE containing images with Win Vista with Visual Studio 2005 installed.

0334In other embodiments, the virtual machine management component <b>1200</b> may provide functionality for one or more of the following actions related to a standard operating environment (an SOE): creating an SOE, updating an SOE, deleting an SOE, finding an SOE, and retrieving an SOE. In still another embodiment, the virtual machine management component <b>1200</b> may provide functionality for one or more of the following actions related to virtual machines: create a virtual machine, update a virtual machine, delete a virtual machine, find a virtual machine, and assignment to or removal from a standard operating environment.

0335A machine type may refer to a non-technical description of a computing environment provided by a virtual machine. Some examples of machine types are “C++ Developer Workstation” or “Secretarial Workstation.” Many virtual machines may be grouped in a single machine type. In one embodiment, the virtual machine management component <b>1200</b> may provide functionality for one or more of the following actions related to machine types: creating machine types, updating a machine type, deleting a machine type, finding a machine type, and retrieving a machine type.

0336In some embodiments, the virtual machine management component <b>1200</b> may provide functionality for creating virtual machines. In one of these embodiments, an administrator or provisioning service creates a new machine type in a database of virtual machines. The machine type is given a meaningful name such as “HR Manager Workstation.” In one embodiment, the machine type name is the name for a class of standard operating environment (SOE) rather than a specific SOE, and multiple SOEs may be assigned to the machine type name. In another embodiment, the machine type may be used to publish the class of virtual machines.

0337In another of these embodiments, a standard operating environment (SOE) is created for the machine type and assigned to the machine type in the database of virtual machines. In one embodiment, the SOE is a virtual machine with a specific hardware and software configuration. A snapshot of the SOE virtual machine may be taken and used as a template for virtual machine clones. In one embodiment, clones of the SOE virtual machine are assigned to users.

0338In one embodiment, an administrator clones an SOE for use by users by creating linked clones of the snapshot of the SOE virtual machine. The linked clone virtual machines may be created in consecutively numbered subfolders in the SOE folder. The linked clones of the SOE may be assigned to the SOE in the database of virtual machines.

0339In another embodiment, an administrator updates a machine type by creating a new SOE, and new linked clones of the SOE. The administrator updates an SOE pointer within a machine type record in the database of virtual machines to point to the new SOE, and marks the old SOE as being superseded. The administrator may create the new SOE by creating a new virtual machine and installing the software, or by creating a full clone of an existing SOE and updating it. As an example the administrator could create a new virtual machine and install Microsoft Windows XP Professional, followed by Windows XP SP1, followed by Microsoft Office 2003, or the administrator could have taken a full clone of an existing SOE with Windows XP and Microsoft Office 2003 already installed, and installs Windows XP SP1 to achieve the same SOE. The new SOE may be created in a new SOE folder and a new SOE record is created in the database of virtual machines. Linked clones of the superseded SOE can be deleted when users have finished with them and the superseded SOE can be deleted when all linked clones have been deleted.

0340In some embodiments, a virtual machine may be designated as a shared virtual machine. In one of these embodiments, a shared virtual machine is an instance of a virtual machine image that is designated for use by multiple users. In another of these embodiments, the shared virtual machine is used by one user at a time and returned to a pool of available virtual machines when not in use. In still another of these embodiments, as the image of a shared virtual machine is executed, users may change the image but may not persist any changes to the image once it is shutdown. In this embodiment, all changes are discarded when the image is shutdown or a user terminates a session.

0341In other embodiments, a virtual machine may be designated as a private virtual machine. In one of these embodiments, a private virtual machine is an instance of a virtual machine image that is designated for use by a specific user. Only that user may be allocated to the image, launch the image, or execute the image. In another of these embodiments, private images will be configured to permit changes to be persisted when the image is shutdown. In still another of these embodiments, changes may be configured to be discarded upon image shutdown as per shared images, depending on the requirements of the user.

0342In some embodiments, a session management component is launched and identifies a virtual machine. In one of these embodiments, the session management component transmits an identification of a user and a virtual machine type identified responsive to a request for access to a resource to the virtual machine management component <b>1200</b>. In another of these embodiments, the session management component requests an identification of a specific virtual machine to launch. In still another of these embodiments, the session management component requests an identification of a location of the configuration and virtual disk files of the identified virtual machine.

0343In some embodiments, a virtual machine is identified responsive to the received identification of the user of the requesting machine. In other embodiments, a virtual machine is identified responsive to a request by the user for a type of virtual machine. In still other embodiments, a virtual machine is identified responsive to a request by the user for a type of computing environment.

0344In some embodiments, the virtual machine management component <b>1200</b> transmits to the session management component an identification of a specific virtual machine to launch. In one of these embodiments, the session management component then proceeds to launch the virtual machine. In another of these embodiments, the virtual machine management component launches the virtual machine.

0345In other embodiments, the virtual machine management component transmits to the session management component an identification of a plurality of virtual machines to launch. In one of these embodiments, the session management component may present an enumeration of available virtual machines to a user. In another of these embodiments, the session management component receives a selection of a virtual machine from the enumeration of available virtual machines and the session management component launches the selected virtual machine. In still other embodiments, the virtual machine management component transmits to the session management component an indication that no virtual machines are available for the user requesting the access. In yet other embodiments, the virtual machine management component <b>1200</b> transmits to the session management component an indication that an existing, executing virtual machine has now been allocated to the user.

0346In yet other embodiments, the virtual machine management component transmits to the session management component an identification of an available virtual machine responsive to accessing a database storing information associated with a plurality of virtual machines, the information including, but not limited to, an identification of the plurality of virtual machines, an identification of a location of files associated with the plurality of virtual machines, an identification of an access control list associated with the plurality of virtual machines, and an indication of availability of the plurality of virtual machines.

0347In one embodiment, when a virtual machine has been identified as a machine to launch, the virtual machine management component <b>1200</b> modifies an access control list associated with the virtual machine responsive to the identification of the user received from the session management component in the initial request. In another embodiment, the virtual machine management component <b>1200</b> modifies the access control list to allow the virtual machine to be launched for the user. In still another embodiment, the virtual machine management component <b>1200</b> transmits additional information associated with the virtual machine to the session management component. The additional information may include network share details relating to a folder storing files associated with the virtual machine. In yet another embodiment, the session management component uses the additional information to map the folder to a mount point, such as a drive letter, in the virtual machine.

0348In some embodiments, virtual machine images—configuration and data files comprising the virtual machine—are stored on a storage area network. In other embodiments, virtual machine images are stored in network attached storage. In one of these embodiments, a file server in communication with the storage area network makes the virtual machine images accessible as if they were located on network attached storage.

0349Referring back to <figref idref="DRAWINGS">FIG. 8</figref>, an identified virtual machine is configured (step <b>814</b>). In brief overview, an execution machine identified by the intermediate machine executes a hypervisor emulating hardware resources required by the requested computing environment. A session management component launches a configured virtual machine in the hypervisor. Configuration occurs of the virtual machine for a particular client machine <b>10</b>. A connection is established between the client machine and the virtual machine.

0350Referring now to <figref idref="DRAWINGS">FIG. 13</figref>, a block diagram depicts one embodiment of a session management component <b>1300</b> in a system providing access to a computing environment by an intermediate machine to a requesting machine. In brief overview, the session management component <b>1300</b> includes an identification component <b>1302</b>, an execution component <b>1304</b>, and a management component <b>1306</b>.

0351The identification component <b>1302</b> is in communication with a virtual machine management component and receives an identification of a virtual machine providing a requested computing environment. In some embodiments, the identification component <b>1302</b> is in communication with the virtual machine management component <b>1200</b>. In one embodiment, the identification component <b>1302</b> receives an identification of an execution machine <b>30</b>′ into which to launch the virtual machine. In some embodiments, the identification component <b>1302</b> identifies an execution machine on which a required hypervisor executes and into which to launch the virtual machine. In other embodiments, the identification component <b>1302</b> receives an identification of the execution machine. In one of these embodiments, the identification component <b>1302</b> receives the identification from the intermediate machine <b>30</b>.

0352In some embodiments, the identification component <b>1302</b> further comprises a transceiver. In one of these embodiments, the transceiver in the identification component <b>1302</b> receives an identification of a user of the requesting machine and transmits the identification of the user to the virtual machine management component. In another of these embodiments, the transceiver receives an identification by a user of a type of computing environment requested and transmits the identification to the virtual machine management component <b>1200</b>. In still another of these embodiments, the transceiver receives an identification by a user of a type of virtual machine requested and transmits the identification of the type of virtual machine requested to the virtual machine management component <b>1200</b>.

0353In some embodiments, the identification component <b>1302</b> receives an identification of a virtual machine providing a requested computing environment, the virtual machine selected responsive to a received identification of a user of the requesting machine. In other embodiments, the identification component <b>1302</b> receives an identification of a virtual machine providing a requested computing environment, the virtual machine selected responsive to a received identification of a type of computing environment requested. In other embodiments, the identification component <b>1302</b> receives an identification of a virtual machine providing a requested computing environment, the virtual machine selected responsive to a received identification of a type of virtual machine requested.

0354The execution component <b>1304</b> launches the virtual machine into a hypervisor. In one embodiment, the hypervisor executes on an execution machine <b>30</b>′. In another embodiment, the execution component <b>1304</b> is in communication with the identification component. In still another embodiment, the execution component <b>1304</b> receives from the identification component <b>1302</b> an identification of an execution machine <b>30</b>′ executing a hypervisor into which to launches the virtual machine. In yet another embodiment, the execution component <b>1304</b> launches the virtual machine into a hypervisor emulating hardware resources required to support the computing environment. In some embodiments, a virtual machine service component executes in the hypervisor. In other embodiments, a virtual machine service component executes in a guest operating system provided by a virtual machine executing in the hypervisor. In one of these embodiments, the virtual machine service component is in communication with the session management component <b>1300</b> and receives configuration information associated with the client machine <b>10</b>.

0355The management component <b>1306</b> establishes a connection between the requesting machine and the virtual machine and manages the connection. In one embodiment, the management component <b>1306</b> provides an internet protocol address associated with the virtual machine to the user of the requesting machine. In another embodiment, the management component <b>1306</b> provides an internet protocol address associated with an execution machine to the user of the requesting machine. In still another embodiment, the management component <b>1306</b> provides a proxy for communication between the requesting machine and the virtual machine. In yet another embodiment, the management component <b>1306</b> establishes a connection between the requesting machine and the virtual machine using a presentation layer protocol.

0356Although described above as separate functional entities, it should be understood that the identification component <b>1302</b>, the execution components <b>1304</b> and the management component <b>1306</b> may be provided as a single functional unit or the functions provided by those components may be grouped into two or more components.

0357In some embodiments, the session management component <b>1300</b> establishes and manages a user's virtual machine session. In one of these embodiments, the session management component <b>1300</b> provides functionality for, without limitation, locating a virtual machine, launching a hypervisor, launching a virtual machine in the hypervisor, connecting a user to the virtual machine, and managing the established connection. In another of these embodiments, the session management component <b>1300</b> publishes a plurality of available virtual machines. In still another of these embodiments, the session management component <b>1300</b> provides, without limitation, enumeration into client drives, mapping of client drives to shared folders on the virtual machine, monitoring of the hypervisor, monitoring of an operating system provided by the virtual machine, and a virtual machine control panel to the user.

0358In one embodiment, the session management component <b>1300</b> provides a virtual machine control panel to the user. The virtual machine control panel may enable a user to switch to the virtual machine, power off the virtual machine, reset the virtual machine, or suspend the virtual machine. In some embodiments, the session management component <b>1300</b> provides the virtual machine control panel only to users authorized to access the functionality of the virtual machine control panel.

0359In some embodiments, a virtual machine service component executes in the hypervisor. In one of these embodiments, the virtual machine service component is in communication with the session management component <b>1300</b> and receives configuration information associated with the client machine <b>10</b>. In another of these embodiments, the session management component <b>1300</b> creates a connection to the virtual machine service component, such as a TCP/IP connection, and communicates with the virtual machine service component over the created connection. In still another of these embodiments, the session management component <b>1300</b> transmits information associated with the client machine <b>10</b>, such as initialization parameters or client monitor geometry, to the virtual machine service component.

0360In some embodiments, the session management component <b>1300</b> identifies a folder containing an image of the identified virtual machine. In one of these embodiments, the folder contains configuration and data files comprising the virtual machine. In another of these embodiments, the session management component <b>1300</b> mounts the folder in the execution machine prior to launching the virtual machine. In still another of these embodiments, the session management component <b>1300</b> copies definition data files associated with the virtual machine onto the execution machine. The session management component <b>1300</b> may copy the definition data files back into the identified folder when a session is completed. In yet another of these embodiments, the configuration and data files are streamed to the execution machine, as described below.

0361In other embodiments, the session management component <b>1300</b> enumerates in the virtual machine a plurality of drives associated with the client machine <b>10</b>. In one of these embodiments, the session management component <b>1300</b> creates a folder associated with each drive in the plurality of drives. In another of these embodiments, the session management component <b>1300</b> stores a folder associated with a drive in the plurality of drives in the mounted folder containing the identified virtual machine. In still another of these embodiments, an enumeration of the stored folder associated with the drive is provided to a user of the client machine <b>10</b>. In some embodiments, a protocol stack located in the hypervisor or in the guest operating system enables drive mapping through other techniques, including techniques enabled by presentation layer protocols.

0362Referring now to <figref idref="DRAWINGS">FIG. 14</figref>, a block diagram depicts one embodiment of a system in which a drive associated with the client machine <b>10</b> is made available to a computing environment. In brief overview, the client machine <b>10</b> has a connection (<b>1</b>) to an execution machine and a connection (<b>2</b>) to a plurality of drives available to a user of the client machine <b>10</b>.

0363The session management component <b>1300</b> creates a folder associated with each drive in the plurality of drives (<b>3</b>). In one embodiment, the session management component <b>1300</b> stores the created folder associated with a drive in the plurality of drives in a virtual machine folder <b>1002</b>, the mounted folder containing configuration and data files associated with the identified virtual machine. In another embodiment, the session management component <b>1300</b> generates a list of shared folders stored in the virtual machine folder <b>1002</b>.

0364The session management component <b>1300</b> notifies the virtual machine service component of the change to the virtual machine folder <b>1002</b> (<b>4</b>). In some embodiments, the session management component <b>1300</b> responds to changes in the client device by rebuilding a shared folder list in the virtual machine folder <b>1002</b>. In one of these embodiments, the session management component <b>1300</b> receives an identification of a modification to the drive associated with the client machine <b>10</b>. In another of these embodiments, the session management component <b>1300</b> transmits a notification to the virtual machine service component identifying the change to the virtual machine <b>1002</b>.

0365For each folder associated with a drive in the virtual machine folder <b>1002</b>, the virtual machine service component provides an indication of a mapped client drive to the virtual machine (<b>5</b>). In one embodiment, the virtual machine service component associates the mapped client drive with a drive letter on the virtual machine. In another embodiment, the virtual machine service component monitors for changes to the shared folder list in the virtual machine folder <b>1002</b>. In some embodiments, an enumeration of the stored folder associated with the drive is provided to a user of the client machine <b>10</b>.

0366In some embodiments, the session management component <b>1300</b> enumerates in the virtual machine a plurality of printers associated with the client machine <b>10</b>. In one of these embodiments, the session management component <b>1300</b> accesses a printer service to acquire an authorization level required to enumerate a printer in the plurality of printers.

0367In one embodiment, a printer associated with the client machine <b>10</b> is shared as a network printer and made accessible to the virtual machine as a network resource. In another embodiment, the virtual machine generates printer output using the TCP/IP and LPR protocols, and this output is intercepted and transmitted to the printer associated with the client machine <b>10</b>. In still another embodiment, the virtual machine transmits printer output to a virtualized hardware resource provided by the hypervisor, such as a COM port on the virtual machine. The output is captured and transmitted to the printer associated with the client machine <b>10</b>. In yet another embodiment, a hypervisor may provide access to a virtual printer or printer port.

0368Referring back to <figref idref="DRAWINGS">FIG. 8</figref>, as part of the configuration process, an execution machine identified by the intermediate machine executes a hypervisor emulating hardware resources required by the requested computing environment. In one embodiment, the hypervisor executes on the intermediate machine. In another embodiment, the hypervisor executes in a terminal services session executing on the intermediate machine. In still another embodiment, the hypervisor executes on the execution machine. In yet another embodiment, the hypervisor executes in a terminal services session executing on the execution machine. In some embodiments, the hypervisor may be executed on the client machine <b>10</b>.

0369In one embodiment, the hypervisor provisions a plurality of hardware resources on the execution machine for use by the requested computing environment. In another embodiment, the hypervisor partitions a plurality of hardware resources on the execution machine and makes the partition available for use by the requested computing environment. In still another embodiment, the hypervisor emulates a plurality of hardware resources on the execution machine for use by the requested computing environment. In yet another embodiment, the hypervisor may partition hardware resources, emulate hardware resources, or provision hardware resources, or all three. For example, a hypervisor may emulate a device (such as a graphics card, network card, and disk), partition the (execution time) of the CPU, and virtualize registers, storage, and underlying devices which they use to fulfill operations on their emulated hardware (such as RAM, and network interface cards).

0370In some embodiments, the session management component <b>1300</b> executes the hypervisor. In one of these embodiments, the session management component <b>1300</b> executes the hypervisor in full-screen mode. In other embodiments, the session management component <b>1300</b> monitors execution of the hypervisor. In one of these embodiments, the session management component <b>1300</b> transmits a notification to the virtual machine management component <b>1200</b> that the virtual machine has terminated when the session management component <b>1300</b> receives an indication that a virtual machine executing in the hypervisor has terminated. In another of these embodiments, the session management component <b>1300</b> receives a notification when the user logs out of a session.

0371In some embodiments, the hypervisor provides a hardware abstraction layer between hardware on the execution machine and a computing environment provided by a virtual machine. In one of these embodiments, there is no operating system between the execution machine hardware and the hypervisor. The hypervisor may be said to be executing “on bare metal.” In another of these embodiments, there is an operating system executing on the execution machine, referred to as a host operating system, and the hypervisor executes from within the operating system. Computing environments provided by a virtual machine may be referred to as guest operating systems.

0372In one embodiment, the hypervisor executes in a terminal server session on a host operating system on the execution machine. The hypervisor may emulate hardware resources required by a computing environment provided by a virtual machine. The hypervisor may partition hardware and provide access to the partition. The hypervisor may also virtualize existing hardware, making it appear to at least one domain on the hardware as if that domain were the only domain accessing the hardware. In another embodiment, output from the computing environment, or an application or resource executing within the computing environment, is passed from the computing environment to a virtualized hardware resource provided by the hypervisor. In still another embodiment, the hypervisor transmits the output to a component such as the session management component <b>1300</b>. The session management component <b>1300</b> may transmit the received output to a client machine <b>10</b> from which a user accesses the computing environment. In yet another embodiment, the hypervisor redirects the output from the virtualized hardware resource to an actual hardware resource, such as a network interface card.

0373In some embodiments, the hypervisor provides a hardware abstraction layer and creates an environment into which a virtual machine may be launched, the virtual machine comprised of configuration and data files creating a computing environment, which may comprise a guest operating system and application programs or other resource. In other embodiments, the hypervisor provides functionality for transmitting data directed to a virtualized hardware resource and redirecting the data to a requesting machine via the session management component <b>1300</b>. In one of these embodiments, the communication between the session management component <b>1300</b> and the hypervisor enable transmission of updates, such as audio updates, updates associated with a graphical user interface, or updates associated with serial COM port input/output, from the virtual machine to the requesting machine. In another of these embodiments, the communication enables transmission of keyboard or mouse or audio updates from the requesting machine to the virtual machine. In still another of these embodiments, where the hypervisor executes within a terminal server session, the hypervisor may map terminal server drives to the computing environment.

0374Referring still to <figref idref="DRAWINGS">FIG. 8</figref>, a virtual machine is configured for access by a particular client machine <b>10</b>. In some embodiments, the management component <b>1300</b> receives an identification of a virtual machine already executing in the hypervisor. In other embodiments, the session management component <b>1300</b> launches the virtual machine in the hypervisor. In one embodiment, the session management component <b>1300</b> receives an identification of a folder containing configuration and data files comprising the virtual machine. In another embodiment, the session management component <b>1300</b> mounts the identified folder in the execution machine.

0375In some embodiments, a virtual machine service component executes in a guest operating system executing within the virtual machine. In one of these embodiments, the virtual machine service component is a system service running in a network service account. In another of these embodiments, the virtual machine service component is configured to initiate execution automatically upon the execution of the computing environment. In still another of these embodiments, the virtual machine service component communicates with the session management component <b>1300</b>. In other embodiments, the virtual machine service component executes in the hypervisor.

0376In some embodiments, a virtual machine service component executes within the virtual machine. In one of these embodiments, after launching the virtual machine in the hypervisor, the session management component <b>1300</b> establishes a connection, such as a TCP/IP connection, with the virtual machine service component. In another of these embodiments, the virtual machine service component establishes the connection. The connection may be a single multiplexed connection between the components or multiple independent connections.

0377In still another of these embodiments, the session management component <b>1300</b> uses the connection to transmit configuration information to the virtual machine service component. The configuration information may be associated with a presentation layer protocol session executing on the client machine <b>10</b> in which output from the virtual machine is presented. The configuration information may also include information associated with display settings and changes, client drive information and authentication data.

0378In other embodiments, the virtual machine service component receives information associated with a printer to which the requesting machine has access. In one of these embodiments, the virtual machine service component access a network printer service to create in the virtual machine a printer connected to the printer to which the requesting machine has access.

0379In still other embodiments, the virtual machine service component transmits session status messages to the session management component <b>1300</b>. In one of these embodiments, the virtual machine service component transmits heartbeat messages to the session management component <b>1300</b>. In another of these embodiments, the virtual machine service component transmits keep-alive messages to the session management component <b>1300</b>, to prevent the session management component <b>1300</b> from shutting down the virtual machine. In still another of these embodiments, the virtual machine service component transmits a message to the session management component <b>1300</b> providing an indication that the user of the client machine <b>10</b> has logged off, shut down, or suspended a session with the computing environment. The virtual machine service component may receive the indication of the user's activity from an authentication module.

0380Referring still to <figref idref="DRAWINGS">FIG. 8</figref>, as described above, a request for access to a resource is received (step <b>802</b>), a method for providing access to the resource is identified (step <b>804</b>), and a virtualized environment may be selected to provide access to a resource (step <b>808</b>). In some embodiments, a client machine <b>10</b> receives the request, identifies a method for providing access, and selects a virtualized environment to provide access to a resource. In one of these embodiments, a mobile computing device connects to a client machine <b>10</b> referred to as a computing device, which identifies a method for providing access to a computing environment, selects a portable computing environment residing in storage on the mobile computing device and provides access to the portable computing environment.

0381Referring ahead to <figref idref="DRAWINGS">FIGS. 89A and 89B</figref>, a storage device and a computing device are depicted. In brief overview, the storage device stores data associated with a computing environment, such as a portable computing environment, which in some embodiments includes virtualization software, a virtual machine image, and user data. A computing device connecting to the storage device, executing a virtual machine, and providing access to the computing environment responsive to data stored in the storage device.

0382Still referring to <figref idref="DRAWINGS">FIG. 89A</figref>, and in further detail, the storage device <b>8905</b> stores the portable computing environment <b>8920</b> of one or more users. In one embodiment, the storage device <b>8905</b> may be any type and form of hard drive, including a micro hard drive. In another embodiment, the storage device <b>8905</b> may be any type and form of portable storage device, such as a flash drive or USB drive, or any type and form of portable storage medium, such as a CD or DVD. In still another embodiment, the storage device <b>8905</b> comprises a flash card, a memory stick, multi-media card or a secure digital card. In some embodiments, the storage device <b>8905</b> may store applications including word processing or office applications, ICA clients, RDP clients, software to establish any type and form of virtual private network (VPN) or SSL VPN connection, software to accelerate network communications or application delivery or any other type and form of application.

0383In one embodiment, the storage device <b>8905</b> may store a virtual machine image. In another embodiment, the storage device <b>8905</b> may comprise a transmitter for transmitting stored data to a computing device <b>8910</b>. In still another embodiment, the storage device <b>8905</b> may comprise a transceiver for accessing stored data, transmitting stored data and receiving data for storage. In yet another embodiment, the storage device <b>8905</b> may comprise stored data comprising an application program for executing a virtual machine on a computing device.

0384In some embodiments, the storage device <b>8905</b> is embedded in a mobile computing device. In other embodiments, the storage device <b>8905</b> is connected to a mobile computing device. In still other embodiments, the storage device <b>8905</b> comprises a portable storage device removable from a computing device.

0385The storage device <b>8905</b> stores data associated with a computing environment. The data may comprise a portable computing environment <b>8920</b>. In one embodiment, the portable computing environment <b>8920</b> is considered portable in that the portable computing environment <b>8920</b> may be easily or conveniently carried and transported from one computing device <b>8910</b> to another computing device <b>8910</b>′. In another embodiment, the portable computing environment <b>8920</b> is considered portable in that the computing environment may be established or executed on any suitable computing device <b>8910</b> with little or no changes to the computing device <b>8910</b>, or in a further embodiment, with little or no maintenance or administration. In still another embodiment, the portable computing environment <b>8920</b> includes a plurality of files representing a desktop environment, or a portion thereof, of a computer system <b>100</b>, which a user desires to execute on the computing device <b>8910</b>. In yet another embodiment, the portable computing environment <b>8920</b> may represent an environment under which a user operates a home or office desktop computer. In some embodiments, the portable computing environment <b>8920</b> represents one or more applications to which a user has access.

0386The portable computing environment <b>8920</b> may include a virtual machine image <b>8925</b>. In one embodiment, the virtual machine image <b>8925</b> comprises a computing environment image, including any of the information, data, files, software, applications and/or operating system needed to execute a computing environment <b>8920</b>, including files needed to execute the computing environment <b>8920</b> via the virtualization software <b>8921</b>. In another embodiment, the virtual machine image <b>8925</b> comprises configuration and data files required to execute a virtual machine providing access to a computing environment requested by a user. In still another embodiment, the virtual machine image <b>8925</b> comprises a virtual machine image as described above.

0387The portable computing environment <b>8920</b> may also include user data <b>8930</b>, including, without limitation, any data, information, files, software or applications of a user. In one embodiment, the user data <b>8930</b> is stored in, or as a part of, the virtual machine image <b>8925</b>. In another embodiment, the user data <b>8930</b> may be created, edited or provided by any software, program, or application of the storage device <b>8905</b> or of the computing device <b>8910</b>.

0388The portable computing environment <b>8920</b> may include virtualization software <b>8921</b>. In some embodiments, the virtualization software <b>8921</b> may comprise any suitable means or mechanisms for a user to access, read and/or write any user data <b>8930</b> included in or provided by the virtualization software <b>8921</b> and/or virtual machine image <b>8925</b>. In one of these embodiments, the virtualization software <b>8921</b> may track, manage and synchronize the access, reading and/or writing of user data <b>8930</b> during an established computing environment <b>8920</b>′ with the user data <b>8930</b> provided on the storage device <b>8905</b>. In another of these embodiments, the user data <b>8930</b> may only be accessed via the virtualization software <b>8921</b> or the established computing environment <b>8920</b>′. In still another of these embodiments, any software, programs or applications of the storage device <b>8905</b> may access the user data <b>8930</b> when the storage device <b>8905</b> is not connected to the computing device <b>120</b> or when a computing environment <b>8920</b>′ is not executing. In yet another of these embodiments, the user data <b>8930</b> may comprise data and files created during a session of an established computing environment <b>8920</b>′.

0389The computing device <b>8910</b> may be any type and form of computer system as described in connection with <figref idref="DRAWINGS">FIG. 1A</figref> and <figref idref="DRAWINGS">FIG. 1B</figref> above. In one embodiment, the computing device <b>8910</b> is a client machine <b>10</b> as described above. In another embodiment, a connection between a computing device <b>8910</b> and a storage device <b>8905</b> provides a user of a client machine <b>10</b> with access to a requested resource. In still another embodiment, the computing device <b>8910</b> receives a request for access to a resource when a connection is made between the computing device <b>8910</b> and the storage device <b>8905</b>. In yet another embodiment, a method for providing access to the resource is identified responsive to information received from the storage device <b>8905</b>.

0390In one embodiment, the computing device <b>8910</b> has a storage element <b>128</b>. In another embodiment, the computing device <b>8910</b> has a network interface <b>118</b>′ connected to network <b>150</b>. In still another embodiment, the computing device <b>8910</b> has a transceiver for accessing data stored in a storage device <b>8905</b> or in a computing device <b>8910</b>′.

0391In some embodiments, the computing device <b>8910</b> comprises an operational or performance characteristic not provided by the storage device <b>8905</b>. In one of these embodiments, the computing device <b>8910</b> comprises elements, such as a processor or a memory, which the storage device <b>8905</b> does not include. In another of these embodiments, the computing device <b>8910</b> provides an I/O device, display device, installation medium, or other peripherals, such as a keyboard or printer not available to the storage device <b>8905</b>. In still another of these embodiments, the computing device <b>8910</b> may provide a feature, a resource, or peripheral desired to be used by the user of the storage device <b>8905</b>. For example, the user may want to access a file or an application provided on a remote machine <b>30</b>′ available via a connection across the network <b>150</b>. In yet another of these embodiments, the computing device <b>8910</b> provides access to a network, such as machine farm <b>38</b>, not available to the storage device <b>8905</b>, or to a user of the storage device <b>8905</b>.

0392In one embodiment, the computing device <b>8910</b> establishes a computing environment <b>8920</b>′ based on the portable computing environment <b>8920</b> provided by the storage device <b>8905</b>. The computing device <b>8910</b> establishes a virtual machine <b>8925</b>′ and a virtualization layer <b>8922</b> to execute the computing environment <b>8920</b>′ based on the virtualization software <b>8921</b> or <b>8921</b>′, virtual machine image <b>8925</b> and/or user data <b>230</b>.

0393In some embodiments, virtualization allows multiple virtual machines <b>8925</b>′, with heterogeneous operating systems to run in isolation, side-by-side on the same physical machine <b>8910</b>. In one embodiment, the virtualization software <b>8921</b> may include a virtual machine image. Virtual machines may include cross-platform X86 PC emulators, such as the products distributed by The Bochs Project at bochs.sourceforge.net, or VMware products manufactured and distributed by VMware, Inc. of Palo Alto, Calif., or products manufactured and distributed by Softricity, Inc., or the Virtuozzo products manufactured and distributed by SWSoft, Inc. of Herndon, Va., or the Microsoft® Virtual PC products manufactured and distributed by Microsoft Corporation of Redmond, Wash. In another embodiment, the virtualization software <b>8921</b> includes any the AppStream products manufactured and distributed by AppStream Inc, of Palo Alto, Calif., or the AppExpress products manufactured and distributed by Stream Theory, Inc of Irvine, Calif.

0394The computing device <b>8910</b> may use any other computing resources of computer system <b>100</b><i>b </i>required by the computing environment <b>8920</b>′. In some embodiments, the hypervisor <b>8923</b> provides a virtualized hardware resource required by the computing environment <b>8920</b>′. In other embodiments, a hypervisor <b>8923</b> provides, via a virtualization layer <b>8922</b>, access to a hardware resource required for execution of a computing environment. In one of these embodiments, the hypervisor <b>8923</b> provisions the hardware resource. In another of these embodiments, the hypervisor <b>8923</b> virtualizes the hardware resource. In still another of these embodiments, the hypervisor <b>8923</b> partitions existing hardware resources and provides access to a partitioned hardware resource.

0395In some embodiments, a virtual machine <b>8925</b>′ executing on a virtualization layer provides access to a computing environment <b>8920</b>′. In other embodiments, a session management component <b>1300</b> executes the virtual machine <b>8925</b>. In still other embodiments, virtualization software <b>8921</b> or <b>8921</b>′ execute the virtual machine <b>8925</b>. In one of these embodiments, the portable computing environment <b>8920</b> includes any type and form of software for virtualizing on a computing device a user-accessible resource, such as an operating system, desktop, application, and any hardware computing resources. In yet other embodiments, virtual machine image <b>8925</b> is accessed to execute a virtual machine <b>8925</b>′. In one of these embodiments, the virtualization software <b>8921</b> or <b>8921</b>′ accesses the virtual machine image.

0396In some embodiments, the virtualization software <b>8921</b> may include software for virtualizing a server, such as the Microsoft Virtual Server products manufactured and distributed by Microsoft Corporation of Redmond, Wash., or the Linux Vserver products distributed by the Linux Vserver Project located at linux-vserver.org. In other embodiments, the virtualization software <b>8921</b> may also include an interpreter or just-in-time compiler, such as the JAVA Virtual Machine (JVM) originally manufactured by Sun Microsystems of Santa Clara, Calif., or the Common Language Runtime (CLR) interpreter manufactured by the Microsoft Corporation.

0397In some embodiments, the computing device <b>8910</b> has the virtualization software <b>8921</b>′ stored or installed in storage element <b>128</b> prior to a connection with the storage device <b>8905</b>. In one embodiment, the virtualization software <b>8921</b>′ does not need to be installed on the computing device <b>8910</b>, and can, instead, be executed from the storage device <b>8905</b>. In another embodiment, the computing device <b>8910</b> installs and executes the virtualization software <b>8921</b> on a per connection basis. In this embodiment, the computing device <b>8910</b> may remove the virtualization software <b>8921</b> from storage element <b>128</b> upon termination of the established computing environment <b>8920</b>′. In still another embodiment, the computing device <b>8910</b> installs and executes the virtualization software <b>8921</b> on a first connection. In yet embodiment, upon other connections, if the computing device <b>8910</b> detects changes to the virtualization software <b>8921</b>, such as a newer version, the computing device <b>8910</b> updates the virtualization software <b>8921</b>, or installs a newer version of the virtualization software <b>8921</b>. In other embodiments, the computing device <b>8910</b> obtains the virtualization software <b>8921</b> from a storage element <b>128</b>″ or a remote machine <b>30</b> accessible via network <b>150</b>.

0398In one embodiment, the virtualization software <b>8921</b> is used to establish a virtualization layer <b>8922</b> on the computing device <b>8910</b>. In another embodiment, the virtualization layer <b>8922</b> provides an abstraction layer that decouples or isolates an application or a hardware resource from the operating system. In still another embodiment, the virtualization layer <b>8922</b> comprises an application to host or run another operating system or application, such as virtual machine <b>8925</b>.

0399In some embodiments, the hypervisor <b>8923</b> comprises the virtualization software <b>8921</b>. In other embodiments, the session management component <b>1300</b> comprises the virtualization software <b>8921</b>. In still other embodiments, the host computing device <b>8910</b> stores virtualization software <b>8921</b>′ in storage element <b>128</b>. In yet other embodiments, the computing device <b>8910</b> accesses a remotely located copy of virtualization software <b>8921</b>′.

0400In some embodiments, the virtualization layer <b>8922</b> and/or virtual machine <b>8925</b> provide an execution environment on the computing device <b>8910</b>. In one of these embodiments, each execution environment is a unique instance of the same execution environment, while, in another of these embodiments, each execution environment may be an instance of different execution environments. Each execution environment may be isolated from and/or not accessible by another execution environment. In other embodiments, the virtualization layer <b>8922</b> and/or virtual machine <b>8925</b> provides an execution context, space or “sandbox” to isolate processes and tasks running on the same operating system.

0401In one embodiment, the virtualization layer <b>8922</b> communicates with a session management component <b>1300</b>. In some embodiments, the session management component <b>1300</b> is software executing in a layer between a hypervisor <b>8923</b> or operating system of the computing device <b>8910</b> and one or more virtual machines <b>8925</b> that provide a virtual machine abstraction to guest operating systems. In other embodiments, as described above, the session management component <b>1300</b> may reside outside of the computing device <b>8910</b> and be in communication with a hypervisor <b>8923</b> or operating system of the computing device <b>8910</b>. In still other embodiment, the session management component <b>1300</b> can load, run or operate the virtual machine image <b>8925</b> from the storage device <b>8905</b> to execute a virtual machine <b>8925</b>′. In yet other embodiments, the session management component <b>1300</b> and hypervisor <b>8923</b> are incorporated into the same application, software or other executable instructions to provide the virtualization layer <b>8922</b>. In further embodiments, the session management component <b>1300</b> is in communication with a virtual machine service component executing within the computing environment <b>8920</b>.

0402In some embodiments and still referring to <figref idref="DRAWINGS">FIG. 89A</figref>, the computing device <b>8910</b> includes a loading mechanism <b>8940</b>, which may comprise software, hardware, or any combination of software and hardware. In one embodiment, the loading mechanism <b>8940</b> comprises an autorun configuration file. In another embodiment, the storage device <b>8905</b> may include the loading mechanism <b>8940</b>. In still another embodiment, the storage device <b>8905</b> includes the loading mechanism <b>8940</b> in an autorun file. In some embodiments, a loading mechanism <b>8940</b> on the storage device <b>8905</b> establishes the computing environment <b>8920</b>′ on the computing device <b>8910</b> based on the portable computing environment <b>8920</b> stored in the storage device <b>8905</b>. In other embodiments, the loading mechanism <b>8940</b>′ of the computing device <b>8910</b> establishes of the computing environment <b>8920</b>′. In still other embodiments, the loading mechanism <b>8940</b> of the storage device <b>8905</b> works in conjunction with the loading mechanism <b>8940</b>′ of the computing device <b>8910</b> to establish the computing environment <b>8920</b>′.

0403In one embodiment, the loading mechanism <b>8940</b> comprises a driver, such as a device driver or a kernel or user-mode driver for connecting to and/or accessing the storage device <b>8905</b>, or the storage element <b>128</b> thereof. In another embodiment, the loading mechanism <b>8940</b> comprises any type and form of executable instructions, such as a program, library, application, service, process, thread or task for accessing the storage element <b>128</b> or storage device <b>8905</b>. In still another embodiment, the loading mechanism <b>8940</b> accesses any type and form of data and information on the storage <b>128</b> to establish the user environment <b>8920</b>′ in accordance with the operations discussed herein. For example, in some embodiments, the loading mechanism <b>8940</b> reads an autorun configuration file in storage element <b>128</b> or on storage device <b>8905</b>. In some embodiments, the loading mechanism <b>8940</b> comprises a plug-n-play (PnP) mechanism by which the operating system of the host computing device <b>8910</b> recognizes the storage device <b>8905</b> upon connection, and loads the drivers to connect to the storage device <b>8905</b>.

0404In one embodiment, the loading mechanism <b>8940</b> upon detection of a connection between the storage device <b>8905</b> and computing device <b>8910</b> initiates the loading, establishing and/or executing of the virtualization software <b>8921</b> and/or the user environment <b>8920</b>′ on the computing device <b>8910</b>. In another embodiment, the loading mechanism <b>8940</b> may comprise any rules, logic, operations and/or functions regarding the authentication and/or authorization of establishing a computing environment <b>8920</b>′ on the computing device <b>8910</b> based on the portable computing environment <b>8920</b>. In still another embodiment, the loading mechanism <b>8940</b> may determine the existence of the virtualization software <b>8921</b>′ on the computing device <b>8910</b> and/or the difference in versions between the virtualization software <b>8921</b> and virtualization software <b>8921</b>′. In yet another embodiment, the loading mechanism <b>8940</b> may store, load, and/or execute the virtualization software <b>8921</b> or <b>8921</b>′ on the computing device <b>8910</b>. In a further embodiment, the loading mechanism <b>8940</b> may store, load, and/or execute the virtual machine image <b>8925</b> on the computing device <b>8910</b> as a virtual machine <b>8925</b> providing access to the computing environment <b>8920</b>′. In still another embodiment, the loading mechanism <b>8940</b> may comprise or provide any type and form of user interface, such as graphical user interface or command line interface.

0405In some embodiments, the virtualization software <b>8921</b>, portable computing environment <b>8920</b> and/or loading mechanism <b>8940</b> are designed and constructed in accordance with the U3 application design specification, or USB smart drive, provided by U3 LLC of Redwood City, Calif. For example, the loading mechanism <b>8940</b> may comprise a U3 launchpad program, and the virtualization software <b>8921</b> and/or portable user environment <b>120</b> may comprise a U3-based application.

0406Referring now to <figref idref="DRAWINGS">FIG. 89B</figref>, a flow diagram depicts one embodiment of the steps taken in a method for providing access to a computing environment on a computing device via a storage device. In brief overview, a method for providing access to a computing environment includes the step of storing, in a storage device, data associated with a computing environment (step <b>8950</b>). A computing device connects to the storage device (step <b>8960</b>). A virtual machine executing on the computing device provides access to the computing environment, based on the data stored in the storage device (step <b>8970</b>).

0407In further detail, a storage device <b>8905</b> stores data associated with a portable computing environment <b>8920</b> (step <b>8950</b>). In one embodiment, the storage device <b>8905</b> stores user data associated with the computing environment. In another embodiment, the storage device <b>8905</b> stores a virtual machine image <b>8925</b>. In still another embodiment, the storage device <b>8905</b> stores data associated with a computing environment, the computing environment comprising at least one application program. In yet another embodiment, the storage device <b>8905</b> stores data associated with a computing environment, the computing environment comprising an operating system.

0408In one embodiment, the storage device <b>8905</b> stores data comprising an operating system. In another embodiment, the storage device <b>8905</b> stores data comprising an application program. In still another embodiment, the storage device <b>8905</b> stores an application program for executing a virtual machine on a computing device. In yet another embodiment, the storage device <b>8905</b> stores virtualization software for executing a virtual machine on a computing device.

0409In some embodiments, the storage device <b>8905</b> may include a connector for establishing a connection between the storage device <b>8905</b> and a computing device. In other embodiments, the storage device <b>8905</b> resides in a computing device, such as a mobile computing device. In one of these embodiments, the storage device <b>8905</b> is embedded in a mobile computing device. In still other embodiments, the storage device <b>8905</b> comprises a portable storage device removable from a computing device.

0410A computing device connects to the storage device (step <b>8960</b>). The storage device <b>8905</b> may connect to the computing device <b>8910</b> by any suitable means and/or mechanism. In one embodiment, the storage device <b>8905</b> connects to a computing device <b>8910</b> via a mobile computing device. In another embodiment, the storage device <b>8905</b> is embedded in a mobile computing device connectable to the computing device <b>8910</b>.

0411Upon connection, a request may be received by the computing device <b>8910</b> for access to a resource. In one embodiment, the request is for a desktop environment. In another embodiment, the request is for an application or for a plurality of applications. In still another embodiment, the request is for a virtual machine.

0412In some embodiments, a determination may be made to provide access to the requested resource via a virtualized environment. In one of these embodiments, the determination is made as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>. In another of these embodiments, the determination is made responsive to information received from the storage device <b>8905</b>, such as a rule requiring the determination.

0413In one embodiment, the computing device <b>8910</b> accesses the storage device <b>8905</b> to access the portable computing environment <b>8920</b>. In another embodiment, the computing device <b>8910</b> obtains the virtualization software <b>8921</b> from the storage device <b>8905</b> to establish a computing environment <b>8920</b>′. In still another embodiment, the computing device <b>8910</b> does not obtain the virtualization software <b>8921</b> from the storage device <b>8905</b> as the computing device <b>8910</b> has access to the virtualization software <b>8921</b> in storage element <b>128</b>′ or via network <b>150</b>. In yet another embodiment, the computing device <b>8910</b> obtains portions of the virtualization software <b>8921</b> from the storage device <b>8905</b>. For example, the virtualization software <b>8921</b> on the storage device <b>8905</b> may be an updated version or have updated files to the virtualization software <b>8921</b>′ on the computing device <b>8910</b>. In some embodiments, the storage device <b>8905</b> transmits information to the computing device <b>8910</b>. In one of these embodiments, the storage device <b>8905</b> transmits the information with a request for access to a resource.

0414A virtual machine executing on the computing device provides access to the computing environment, based on the data stored in the storage device (step <b>8970</b>). In one embodiment, the computing device <b>8910</b> retrieves data from the storage device <b>8905</b>. In another embodiment, the computing device <b>8910</b> accesses the storage device <b>8905</b> to obtain a virtual machine image <b>8925</b> used to execute the virtual machine. In still another embodiment, the computing device <b>8910</b> accesses the storage device <b>8905</b> to obtain data or information identifying a location of the portable computing environment <b>8920</b> that may be accessible to the computing device <b>8910</b>. For example, the storage device <b>8905</b> may comprise user data <b>8930</b> identifying a Uniform Resource Locator (URL) associated with a location on which a virtual machine image <b>8925</b> is stored, the URL accessible by the computing device <b>8910</b> via network <b>150</b>. In yet another embodiment, the computing device <b>8910</b> accesses a storage element identified by the user data <b>8930</b>, for example, a storage element or remote machine <b>30</b> on the network <b>150</b> storing the virtual machine image <b>8925</b>.

0415In some embodiments, the computing device <b>8910</b> mounts the storage device <b>8905</b> as a storage, such as a disk, available to the computing device <b>8910</b>. In one of these embodiments, the computing device <b>8910</b> mounts the storage device <b>8905</b> as removable media. In other embodiments, the loading mechanism <b>8940</b> accesses the storage device <b>8905</b>.

0416The computing device <b>8910</b> establishes an environment for executing or providing access to the computing environment <b>8920</b>′. In one embodiment, a virtual machine may be executed in the computing environment <b>8920</b>′ to provide access to a requested resource. In another embodiment, a virtual machine is the requested resource. In still another embodiment, a virtual machine <b>8925</b>′ executes a virtual machine <b>8925</b>″.

0417In one embodiment, the computing device <b>8910</b> executes a virtual machine responsive to a virtual machine image <b>8925</b> stored in the storage device <b>8905</b>. In another embodiment, the computing device <b>8910</b> executes a virtual machine <b>8925</b>′ responsive to the data stored in the storage device <b>8905</b>. In still another embodiment, the computing device <b>8910</b> executes the virtual machine responsive to a policy stored in the storage device.

0418In one embodiment, the computing device <b>8910</b> retrieves data stored in the storage device <b>8905</b>. In another embodiment, the computing device <b>8910</b> uses an application program stored in the storage device <b>8905</b> to access the data. In still another embodiment, the computing device <b>8910</b> provides access to a computing environment by executing an operating system providing access to one or more applications identified by information stored in the storage device, the operating system and the one or more applications having access to user data stored in the storage device <b>8905</b>.

0419In one embodiment, the computing device <b>8910</b> installs and/or loads the virtualization software <b>8921</b> to establish the virtualization layer <b>8922</b>. In some embodiments, the virtualization software <b>8921</b> is designed and constructed as a portable application that can execute, load or establish the virtualization layer <b>8922</b> on the computing device <b>8910</b> without requiring installation of the virtualization software <b>8921</b>. In other embodiments, the virtualization software <b>8921</b> is automatically installed on the computing device <b>8910</b> via an installation script. In one of these embodiments, the virtualization software <b>8921</b> is installed without requiring a reboot. In another of these embodiments, the virtualization software <b>8921</b> is installed and the virtualization layer <b>8922</b> established transparently to a user. In still other embodiments, the virtualization layer <b>8922</b> is established using the virtualization software <b>8921</b>′ stored on the computing device <b>8910</b> or accessed via network <b>150</b>.

0420In some embodiments, the computing device <b>8910</b> executes a hypervisor <b>8923</b> to establish the virtualization layer <b>8922</b>. In other embodiments, a hypervisor <b>8923</b> on the computing device <b>8910</b> and in communication with a hypervisor <b>8923</b>′ on a remote machine <b>30</b>′ establishes the virtualization layer <b>8922</b>. In still other embodiments, a hypervisor <b>8923</b> in communication with a session management component <b>1300</b> establishes the virtualization layer <b>8922</b>. In one of these embodiments, upon establishment of the virtualization layer <b>8922</b>, the session management component <b>1300</b> identifies, provisions, and/or executes a virtual machine in the virtualization layer <b>8922</b> as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>. In yet other embodiments, the loading mechanism <b>8940</b> establishes the virtualization layer <b>8922</b>. In further embodiments, the computing device <b>8910</b> establishes a virtualization layer <b>8922</b> in which a virtual machine service component executes.

0421In one embodiment, the virtualization layer <b>8922</b> has been established prior to the storage device <b>8905</b> connecting to the computing device <b>8910</b>. For example, the virtualization layer <b>8922</b> may have been established for another computing environment <b>8920</b>′ or during a previous connection of the same or a different storage device <b>8905</b>. In some embodiments, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> establishes the virtualization layer <b>8922</b> and actuates, starts, or executes a session management component <b>1300</b> and/or hypervisor <b>8923</b>. In other embodiments, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> executes session management component <b>1300</b> and/or hypervisor <b>8923</b> upon loading or executing a virtual machine <b>8925</b>.

0422The computing device <b>8910</b> provides access to the computing environment <b>8920</b>′ based on the portable computing environment <b>8920</b> (step <b>8970</b>). In one embodiment, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> accesses the virtual machine image <b>8925</b> from storage device <b>8905</b> and executes the virtual machine image <b>8925</b> as a virtual machine <b>8925</b>′ in the established virtualized environment <b>8922</b>. In another embodiment, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> automatically loads, executes or otherwise establishes the computing environment <b>8920</b> with the virtualization layer <b>8922</b> upon detection of a connection over network <b>150</b>. In still another embodiment, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> automatically loads, executes or otherwise establishes the computing environment <b>8920</b> and the virtualization layer <b>8922</b> upon detection of existence or identification of the portable computing environment <b>8920</b> in storage element <b>128</b>.

0423In some embodiments, a user may select the virtual machine image <b>8925</b> from the storage device <b>8905</b> for execution as a virtual machine <b>8925</b>′ via any type and form of user interface. In one of these embodiments, the virtualization software <b>8921</b>, virtualization layer <b>8922</b>, hypervisor <b>8923</b>, or loading mechanism <b>8940</b> may display a user interface for a user to identify a virtual machine image <b>8925</b>, and/or to execute a virtual machine <b>8925</b>′ based on a virtual machine image <b>8925</b>. In another of these embodiments, a client, such as an ICA client, an RDP client, or an X11 client, executes on the computing device <b>8910</b> and provides the user interface to the user.

0424In some embodiments, a user may access, read, and/or write user data <b>8930</b> during the course of using the established computing environment <b>8920</b>′. In one of these embodiments, a user of the computing device <b>8910</b> may access, read and/or write the user data <b>8930</b> to the storage device <b>8905</b>. In another of these embodiments, a user of the computing device <b>8910</b> may edit or modify user data <b>8930</b> or may create new data and information in user data <b>8930</b>.

0425In other embodiments, a user of the computing device <b>8910</b> may access, read, and/or write user data to the storage <b>128</b>′ of the computing device <b>8910</b>. In still other embodiments, the computing device <b>8910</b> may synchronize user data <b>8930</b> on the computing device <b>8910</b> with user data <b>8930</b> on the storage device <b>8905</b>. In one of these embodiments, the computing device <b>8910</b> uses the virtualization layer <b>8922</b> or the loading mechanism <b>8940</b> to synchronize the user data <b>8930</b>. In yet other embodiments, the storage device <b>8905</b> may have a program or application for synchronizing data between the storage device <b>8905</b> and the computing device <b>8910</b>.

0426In some embodiments, the storage device <b>8905</b> may disconnect from the computing device <b>8910</b> at any point in time during the established computing environment <b>8920</b>′. In other embodiments, the storage device <b>8905</b> may disconnect after the computing environment <b>8920</b>′ is terminated on the computing device <b>8910</b>. In still other embodiments, the computing environment <b>8920</b>′ is automatically terminated upon disconnection of the storage device <b>8905</b> to the computing device <b>8910</b>. In yet other embodiments, the computing environment <b>8920</b>′ may remain established on the computing device <b>8910</b> after the storage device <b>8905</b> disconnects from the computing device <b>8910</b>. In one of these embodiments, once the computing environment <b>8920</b>′ is established on the computing device <b>8910</b>, the storage device <b>8905</b> may be disconnected.

0427In some embodiments, the storage device <b>8905</b> can access, read, and/or write user data <b>8930</b> to any portion of the portable computing environment <b>8920</b>. In one of these embodiments, although the portable computing environment <b>8920</b> is not established or virtualized on computing device <b>8910</b>, the storage device <b>8905</b> can still access, read, and/or write to and from the user data <b>8930</b>. In other embodiments, a user may use a first application in the established computing environment <b>8920</b>′ to access a file of the user data <b>8930</b>. In still other embodiments, the user may use a second application on the storage device <b>8905</b> to access the same file of the user data <b>8930</b>. In yet other embodiments, the virtualization software <b>8921</b> or virtual image <b>8925</b> allows access to the user data <b>8930</b>, even though virtualization software <b>8921</b> or virtual machine image <b>8925</b> is not executing or operating.

0428Although <figref idref="DRAWINGS">FIGS. 89A and 89B</figref> are generally discussed with one portable computing environment <b>8920</b> stored in the storage device <b>8905</b>, the storage device <b>8905</b> may store a plurality of portable computing environments <b>8920</b> for establishing a corresponding plurality of computing environments <b>8920</b>′ on the computing device <b>8910</b>. In some embodiments, the computing device <b>8910</b>, loading mechanism <b>8940</b>, or the virtualized layer <b>8920</b> provides a user interface for the user to select a portable computing environment from storage to establish the computing environment <b>8920</b>. For example, the storage device <b>8905</b> or the computing device <b>8910</b> may have a portable computing environment selection mechanism as is further discussed in connection with <figref idref="DRAWINGS">FIG. 92A</figref> and with <figref idref="DRAWINGS">FIG. 93A</figref>. In other embodiments, the computing device <b>8910</b>, loading mechanism <b>8940</b>, or the virtualized layer <b>8922</b> uses one of the plurality of portable computing environments based on a characteristic of the computing device, such as operating system type, or based on user data identifying the portable computing environment to use for the computing device.

0429Referring now to <figref idref="DRAWINGS">FIG. 90A</figref>, a mobile computing device <b>9005</b> is depicted. In brief overview, the mobile computing device <b>9005</b> may be any type and form of computer system as described in connection with <figref idref="DRAWINGS">FIG. 1A</figref> and <figref idref="DRAWINGS">FIG. 1B</figref> above. In one embodiment, the mobile computing device <b>9005</b> comprises a storage device, such as a storage device <b>8905</b> as described in connection with <figref idref="DRAWINGS">FIG. 89A</figref> and <figref idref="DRAWINGS">FIG. 89B</figref>. In another embodiment, the mobile computing device <b>9005</b> is connected to a storage device <b>8905</b>. In still another embodiment, the mobile computing device <b>9005</b> comprises a portable storage device removable from a computing device. In yet another embodiment, the mobile computing device <b>9005</b> has a network interface <b>118</b> used to connect to remote machines <b>30</b> or client machines <b>10</b> on the network <b>150</b>, such as the computing device <b>8910</b>. The storage device <b>8905</b> may store a portable computing environment <b>8920</b>, which in some embodiments includes virtualization software <b>8921</b>, a virtual image <b>8925</b>, and user data <b>8930</b>.

0430In some embodiments, the mobile computing device <b>9005</b> stores data associated with a computing environment, executes a virtual machine, and provides access to the computing environment responsive to data stored in the mobile computing device <b>9005</b>. In one of these embodiments, the mobile computing device <b>9005</b> comprises a stored virtual machine image. In another of these embodiments, the mobile computing device <b>9005</b> comprises an application program for executing a virtual machine on a computing device. In still another of these embodiments, the mobile computing device <b>9005</b> provides access to a computing environment by executing an operating system with access to one or more applications identified via data stored on the mobile computing device, the operating system and the one or more applications having access to the user data on the mobile computing device. In other embodiments, the mobile computing device <b>9005</b> stores the portable computing environment <b>8920</b> of one or more users in storage provided by a storage device, such as a storage device <b>8905</b> as described above in connection with <figref idref="DRAWINGS">FIGS. 89A and 89B</figref>.

0431In one embodiment, the mobile computing device <b>9005</b> decrypts stored data. In another embodiment, the mobile computing device <b>9005</b> prevents one of unauthenticated and unauthorized access by a user of the mobile computing device <b>9005</b> to a computing environment provided by the mobile computing device <b>9005</b>.

0432Referring now to <figref idref="DRAWINGS">FIG. 90B</figref>, a flow diagram depicts one embodiment of the steps taken in a method for providing a computing environment by a mobile computing device. In brief overview, a method includes the step of storing, in a mobile computing device <b>9005</b>, data associated with a computing environment (step <b>9020</b>). A virtual machine executing on the mobile computing device provides access to the computing environment, based on the stored data (step <b>9025</b>).

0433In further detail, the mobile computing device <b>9005</b> stores data associated with a computing environment (step <b>9020</b>). In one embodiment, the mobile computing device <b>9005</b> receives the data associated with the computing device from a storage device connected to the mobile computing device <b>9005</b>. In another embodiment, the mobile computing device stores the data associated with the computing environment in a storage device <b>8905</b> embedded in the mobile computing device. In still another embodiment, the mobile computing device <b>9005</b> stores user data associated with the computing environment. In yet another embodiment, the mobile computing device <b>9005</b> stores a virtual machine image.

0434In one embodiment, the mobile computing device <b>9005</b> stores data associated with a computing environment, the computing environment comprising at least one application program. In another embodiment, the mobile computing device <b>9005</b> stores data associated with a computing environment, the computing environment comprising an operating system. In still another embodiment, the mobile computing device <b>9005</b> stores data comprising an operating system. In yet another embodiment, the mobile computing device <b>9005</b> stores data comprising an application program. In some embodiments, the mobile computing device <b>9005</b> stores an application program for executing a virtual machine. In other embodiments, the mobile computing device <b>9005</b> stores virtualization software for executing a virtual machine.

0435In some embodiments, a request may be received by the mobile computing device <b>9005</b> for access to a resource. In one of these embodiments, the request is for a desktop environment. In another of these embodiments, the request is for an application or for a plurality of applications. In still another of these embodiments, the request is for a virtual machine. In yet another of these embodiments, the request is for access to a computing environment.

0436In some embodiments, a determination may be made to provide access to the requested resource via a virtualized environment. In one of these embodiments, the determination is made as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>. In another of these embodiments, the determination is made responsive to information received from the mobile computing device <b>9005</b>, such as a rule requiring the determination.

0437A virtual machine executing on the mobile computing device provides access to the computing environment, based on the stored data (step <b>9025</b>). In one embodiment, an application program stored in the mobile computing device <b>9005</b> executes to access data associated with the computing environment. In another embodiment, the mobile computing device <b>9005</b> executes virtualization software, at least a portion of which is stored on the mobile computing device <b>9005</b>. In still another embodiment, the mobile computing device <b>9005</b> provides access to a computing environment by executing an operating system with access to one or more applications stored on the mobile computing device, the operating system and the one or more applications having access to user data stored in the mobile computing device <b>9005</b>.

0438In one embodiment, the mobile computing device <b>9005</b> executes a virtual machine, responsive to data stored in the mobile computing device <b>9005</b>. In another embodiment, the mobile computing device executes a virtual machine responsive to a policy stored in the mobile computing device <b>9005</b>. In still another embodiment, the mobile computing device <b>9005</b> executes a virtual machine that provides access to a requested resource or computing environment, the virtual machine executed responsive to a virtual machine image stored in the mobile computing device <b>9005</b>. In yet another embodiment, the mobile computing device <b>9005</b> transfers execution of the virtual machine to a computing device <b>8910</b>.

0439Although <figref idref="DRAWINGS">FIGS. 90A and 90B</figref> are generally discussed with one portable user environment <b>8920</b> stored in storage <b>8905</b> of the mobile computing device <b>9005</b>, the mobile computing device <b>9005</b> may store a plurality of portable computing environments <b>8920</b> for establishing a corresponding plurality of computing environments <b>8920</b>′ on the mobile computing device <b>9005</b>.

0440Referring now to <figref idref="DRAWINGS">FIG. 91A</figref>, a mobile computing device and a computing device are depicted. In brief overview, the mobile computing device stores data associated with a computing environment. The computing device connects to the mobile computing device, executes a virtual machine, and provides access to the computing environment responsive to data stored in the mobile computing device. In one embodiment, the virtual machine executing on the computing device provides access to the computing environment.

0441In one embodiment, the mobile computing device <b>9005</b> may be any type and form of computer system as described in connection with <figref idref="DRAWINGS">FIG. 1A</figref> and <figref idref="DRAWINGS">FIG. 1B</figref> above. In another embodiment, the mobile computing device <b>9005</b> comprises a storage device <b>8905</b> as described above in connection with <figref idref="DRAWINGS">FIG. 90A</figref> and <figref idref="DRAWINGS">FIG. 90B</figref>. In another embodiment, the mobile computing device may be a mobile computing device <b>9005</b> as described above in connection with <figref idref="DRAWINGS">FIG. 90A</figref> and <figref idref="DRAWINGS">FIG. 90B</figref>. In some embodiments, the mobile computing device <b>9005</b> provides access to a portable computing environment <b>8920</b> of one or more users in storage provided by a storage device, such as a storage device <b>8905</b> as described above in connection with <figref idref="DRAWINGS">FIGS. 89A and 89B</figref>.

0442In some embodiments, the mobile computing device <b>9005</b> and the computing device <b>8910</b> may have the same processor or computer architecture, such as an X86 based processor architecture. In other embodiments, the mobile computing device <b>9005</b> may have a different processor or architecture than the computing device <b>8910</b>. For example, the computing device <b>8910</b> may be a SPARC (Scalable Processor Architecture) and the mobile computing device <b>9005</b> may be an ARM based architecture. In some embodiments, the mobile computing device <b>9005</b> and the computing device <b>8910</b> may both operate a processor, or a data address or bus using the same numbers of bits, such as a 32-bit or 64-bit processor or bus. In other embodiments, the mobile computing device <b>9005</b> and the computing device <b>8910</b> may operate on processors and/or a data bus with different bit architectures. Furthermore, the mobile computing device <b>9005</b> and computing device <b>8910</b> may operate the same operating system, in one embodiment, and different operating systems, in another embodiment. For example, the mobile computing device <b>9005</b> may operate a PALM operating system while the computing device <b>8910</b> runs a WINDOWS operating system.

0443In one embodiment, a mobile computing device <b>9005</b> has multiple processors. One processor may have higher performance characteristics than the other processor, and each processor may share one or more storage and memory elements. For example, a storage element, such as a disk drive or portable storage device, may include a computing environment. The mobile computing device <b>9005</b> may also have a switching mechanism to switch between using a first processor having higher performance characteristics and a second processor having lower performance characteristics, based on operating conditions and applications executing on the device. The processor having lower performance characteristics may be used to execute applications with lower power requirements, such as typical PDA functionality of calendar access and email. When an application requires more power, the mobile computing device <b>9005</b> may automatically switch execution of such applications to the more powerful processor.

0444The computing device <b>8910</b> connects to the mobile computing device, executes a virtual machine, and provides access to the computing environment responsive to data stored in the mobile computing device <b>9005</b>. In one embodiment, the computing device <b>8910</b> may mount the storage device <b>8905</b> of the mobile computing device <b>9005</b> as a removable hard drive or storage element <b>128</b>′ of the computing device <b>8910</b>. In some embodiments, the mobile computing device <b>9005</b> may be a plug and play device (PnP) of the computing device <b>8910</b>, such that a PnP protocol manufactured by Microsoft Corporation of Redmond, Wash., is used between the mobile computing device <b>9005</b> and computing device <b>8910</b>, such as via I/O devices <b>130</b><i>a</i>-<b>130</b><i>n </i>or network interfaces <b>118</b>, <b>118</b>′.

0445In some embodiments, the computing device <b>8910</b> comprises an operational or performance characteristic not provided by the mobile computing device <b>9005</b>. In one of these embodiments, the computing device <b>8910</b> has a more powerful processor <b>102</b>′ and/or larger memory <b>122</b>′ than the processor <b>102</b> and memory <b>122</b> of the mobile computing device <b>9005</b>. In another of these embodiments, the computing device <b>8910</b> provides an I/O device <b>130</b><i>b</i>, display device, installation medium, or other peripherals, such as a keyboard or printer not available to the mobile computing device <b>9005</b>. In still another of these embodiments, the computing device <b>8910</b> may provide a feature, a resource, or peripheral desired to be used by the user of the mobile computing device <b>9005</b>. For example, the user may want to access a file or an application provided on a remote machine <b>30</b>′ available via a connection across the network <b>150</b>. In yet another of these embodiments, the computing device <b>8910</b> provides access to machines on a network <b>150</b>, such as those in machine farm <b>38</b>, not available to the mobile computing device <b>9005</b>, or to a user of the mobile computing device.

0446In one embodiment, the computing device <b>8910</b> provides access to a computing environment <b>8920</b>′ based on the portable computing environment <b>8920</b> provided in the mobile computing device <b>9005</b>. The computing device <b>8910</b> executes a virtual machine <b>8925</b>′ and a virtualization layer <b>8922</b> to execute the computing environment <b>8920</b>′ based on the virtualization software <b>8921</b> or <b>8921</b>′, virtual machine image <b>8925</b>, or user data <b>230</b>. In some embodiments, the computing device comprises a transceiver for accessing data stored in the mobile computing device <b>9005</b>.

0447In some embodiments, a loading mechanism on the mobile computing device <b>9005</b> actuates the establishment of the computing environment <b>8920</b>′ on the computing device <b>8910</b> based on the portable computing environment <b>8920</b> stored in the mobile computing device <b>9005</b>. In other embodiments, the loading mechanism <b>8940</b> of the computing device <b>8910</b> actuates the establishment of the computing environment <b>8920</b>′. In yet another embodiment, a loading mechanism on the mobile computing device <b>9005</b> works in conjunction with the loading mechanism <b>8940</b> of the computing device <b>8910</b> to establish the computing environment <b>8920</b>′.

0448Referring now to <figref idref="DRAWINGS">FIG. 91B</figref>, a flow diagram depicts one embodiment of the steps taken in a method for providing access to a computing environment on a computing device via a mobile computing device. In brief overview, a method includes the step of storing, in a mobile computing device, data associated with a computing environment (step <b>9155</b>). A computing device connects to the mobile computing device (step <b>9160</b>). A virtual machine executing on the computing device provides access to a computing environment, based on the data stored in the mobile computing device (step <b>9165</b>).

0449A mobile computing device stores data associated with a computing environment (step <b>9155</b>). In one embodiment, the mobile computing device <b>9005</b> may store data associated with a computing environment as described above in connection with <figref idref="DRAWINGS">FIGS. 90A and 90B</figref>. In one embodiment, the mobile computing device <b>9005</b> may comprise a storage device embedded in the mobile computing device <b>9005</b>, such as the storage device <b>8905</b> described in connection with <figref idref="DRAWINGS">FIG. 89A</figref> through <figref idref="DRAWINGS">FIG. 90B</figref>.

0450The computing device <b>8910</b> connects to the mobile computing device <b>9005</b> by any suitable means and/or mechanism (step <b>9160</b>). In one embodiment, the computing device <b>8910</b> connects to a storage device, such as a storage device <b>8905</b> as described above in connection with <figref idref="DRAWINGS">FIG. 89A</figref> and <figref idref="DRAWINGS">FIG. 89B</figref>, via the mobile computing device <b>9005</b>. Upon connection, a request may be received by the computing device <b>8910</b> for access to a resource. In one embodiment, the request is for access to a desktop environment. In another embodiment, the request is for an application or for a plurality of applications. In still another embodiment, the request is for a virtual machine. In some embodiments, a determination may be made to provide access to the requested resource via a virtualized environment. In one of these embodiments, the determination is made as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>. In another of these embodiments, the determination is made responsive to information received from the mobile computing device <b>9005</b>, such as a rule requiring the determination.

0451In one embodiment, the computing device <b>8910</b> accesses the mobile computing device <b>9005</b> to obtain the portable user environment <b>8920</b>. In another embodiment, the computing device <b>8910</b> obtains the virtualization software <b>8921</b> to establish the virtualized environment <b>8922</b>. In still another embodiment, the computing device <b>8910</b> does not obtain the virtualization software <b>8921</b> from the mobile computing device <b>9005</b> as the computing device <b>8910</b> has access to the virtualization software <b>8921</b> in storage element <b>128</b>′ or via network <b>150</b>. In yet another embodiment, the computing device <b>8910</b> obtains portions of the virtualization software <b>8921</b> from the mobile computing device <b>9005</b>. For example, the virtualization software <b>8921</b> on the mobile computing device <b>9005</b> may be an updated version or have updated files to the virtualization software <b>8921</b>′ on the computing device <b>8910</b>. In some embodiments, the mobile computing device <b>9005</b> transmits information to the computing device <b>8910</b>. In one of these embodiments, the mobile computing device <b>9005</b> transmits the information with a request for access to a resource.

0452In one embodiment, the computing device <b>8910</b> accesses the mobile computing device <b>9005</b> to obtain the virtual machine image <b>8925</b>. In another embodiment, the computing device <b>8910</b> accesses the mobile computing device <b>9005</b> to obtain data or information identifying a location of the portable user environment <b>8920</b> in any storage that may be accessible to the computing device <b>8910</b>. For example, the mobile computing device <b>9005</b> may comprise user data <b>8930</b> identifying a Uniform Resource Locator (URL) associated with a location on which a virtual machine image <b>8925</b> is stored, the URL accessible by the computing device <b>8910</b> via network <b>150</b>. In still another embodiment, the computing device <b>8910</b> accesses a storage element identified by the user data <b>8930</b>, for example, a storage element on network <b>150</b> storing the virtual machine image <b>8925</b>. In some embodiments, the computing device <b>8910</b> mounts the mobile computing device <b>9005</b> as a storage element, such as a disk, available to the computing device <b>8910</b>. For example, in one embodiment, the computing device <b>8910</b> mounts the mobile computing device <b>9005</b> as removable media. In one embodiment, the loading mechanism <b>8940</b> accesses the mobile computing device <b>8905</b>.

0453In some embodiments, the computing device <b>8910</b> provides access to a computing environment by executing an operating system with access to one or more applications identified via data stored on the mobile computing device, the operating system and the one or more applications having access to the user data on the storage device. In other embodiments, the computing device prevents one of unauthenticated or unauthorized access by a user of the mobile computing device <b>9005</b> to a computing environment provided by the computing device <b>8910</b>. In still other embodiments, the computing device <b>8910</b> decrypts data stored on the mobile computing device <b>9005</b>.

0454A virtual machine executing on the computing device <b>8910</b> provides access to a computing environment, based on data stored in the mobile computing device <b>9005</b> (step <b>9165</b>). In one embodiment, the computing device <b>8910</b> establishes a virtualized environment for providing access to the computing environment <b>8920</b>′ by executing the virtual machine <b>8925</b>. In another embodiment, a virtual machine may be executed in the user environment <b>8920</b>′ to provide access to a requested resource. In still another embodiment, a virtual machine is the requested resource. In some embodiments, the computing device <b>8910</b> executes a virtual machine responsive to a virtual machine image <b>8925</b> stored in the mobile computing device <b>9005</b>. In other embodiments, the computing device <b>8910</b> executes a virtual machine responsive to data stored in the mobile computing device <b>9005</b>.

0455In one embodiment, an application program stored in the mobile computing device <b>9005</b> is executed to access data associated with a computing environment. In another embodiment, the computing device <b>8910</b> executes virtualization software <b>8921</b>′ by accessing at least a portion of the virtualization software <b>8921</b> stored in the mobile computing device <b>9005</b>.

0456In one embodiment, the computing device <b>8910</b> executes the virtualization software <b>8921</b> to establish the virtualization layer <b>8922</b>. In some embodiments, the virtualization software <b>8921</b> is automatically installed on the host computing device <b>8910</b> via an installation script. In one of these embodiments, the virtualization software <b>8921</b> is installed without requiring a reboot. In another of these embodiments, the virtualization software <b>8921</b> is installed and the virtualization layer <b>8922</b> established transparently to a user.

0457In some embodiments, the computing device <b>8910</b> executes a hypervisor <b>8923</b> to establish the virtualization layer <b>8922</b>. In other embodiments, a hypervisor <b>8923</b> on the computing device <b>8910</b> and in communication with a hypervisor <b>8923</b>′ on a remote machine <b>30</b>′ establishes the virtualization layer <b>8922</b>. In still other embodiments, a hypervisor <b>8923</b> in communication with a session management component <b>1300</b> establishes the virtualization layer <b>8922</b>. In one of these embodiments, upon establishment of the virtualization layer <b>8922</b>, the session management component <b>1300</b> identifies, provisions, and/or executes a virtual machine in the virtualization layer <b>8922</b> as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>. In yet other embodiments, the loading mechanism <b>8940</b> establishes the virtualization layer <b>8922</b>. In one embodiment, the computing device <b>8910</b> establishes a virtualization layer <b>8922</b> in which a virtual machine service component executes.

0458In one embodiment, the virtualization layer <b>8922</b> has been established prior to the mobile device <b>9005</b> connecting to the computing device <b>8910</b>. For example, the virtualization layer <b>8922</b> may have been established for another user environment <b>8920</b>′ or during a previous connection of the same or different mobile computing device <b>9005</b>. In some embodiments, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> establishes the virtualization layer <b>8922</b> and actuates, starts, or executes a session management component <b>1300</b> and/or hypervisor <b>8923</b>. In other embodiments, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> executes the session management component <b>1300</b> and/or hypervisor <b>8923</b> upon loading or executing a virtual machine <b>8925</b>.

0459In some embodiments, the computing device <b>8910</b> establishes, executes or otherwise provides the computing environment <b>8920</b>′ based on the portable computing environment <b>8920</b>. In one embodiment, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> accesses the virtual image <b>8925</b> from the mobile computing device <b>9005</b> and loads or executes the virtual machine image <b>8925</b> as a virtual machine <b>8925</b> in the established virtualized environment <b>8922</b>. In another embodiment, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> automatically loads, executes or otherwise establishes the computing environment <b>8920</b> with the virtualization layer <b>8922</b> upon detection of a connection over network <b>150</b>. In still another embodiment, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> automatically loads, executes or otherwise establishes the computing environment <b>8920</b> and the virtualization layer <b>8922</b> upon detection of existence or identification of the portable computing environment <b>8920</b> on the mobile computing device <b>9005</b>.

0460In some embodiments, a user may select the virtual machine image <b>8925</b> from the mobile computing device <b>9005</b> for execution as a virtual machine <b>8925</b> via any type and form of user interface. In one of these embodiments, the virtualization software <b>8921</b>, virtualization layer <b>8922</b>, hypervisor <b>8923</b>, or loading mechanism <b>8940</b> may display a user interface for a user to identify a virtual image <b>8925</b>, and/or to execute a virtual machine <b>8925</b> based on a virtual image <b>8925</b>. In another of these embodiments, a client, such as an ICA client, an RDP client, or an X11 client, executes on the computing device <b>8910</b> and provides the user interface to the user.

0461In some embodiments, a user may access, read, and/or write user data <b>8930</b> during the course of using the established user environment <b>8920</b>′. In one of these embodiments, the user host computing device <b>8910</b> may access, read and/or write the user data <b>8930</b> to the mobile computing device <b>9005</b>. In another of these embodiments, the user of the computing device <b>8910</b> may edit or modify user data <b>8930</b> or may create new data and information in user data <b>8930</b>.

0462In other embodiments, a user of the computing device <b>8910</b> may access, read, and/or write user data to the storage element <b>128</b>′ of the computing device <b>8910</b>. In still other embodiments, the computing device <b>8910</b> may synchronize user data <b>8930</b> on the computing device <b>8910</b> with user data <b>8930</b> on the mobile computing device <b>8905</b>. In one of these embodiments, the computing device <b>8910</b> uses the virtualization layer <b>8922</b> or the loading mechanism <b>8940</b> to synchronize the user data <b>8930</b>. In yet other embodiments, the mobile computing device <b>9005</b> may have a program or application for synchronizing data, such as files and folders, between the mobile computing device <b>9005</b> and the computing device <b>8910</b>.

0463In one embodiment, the mobile computing device <b>9005</b> may disconnect from the computing device <b>8910</b>. In some embodiments, the mobile computing device <b>9005</b> may disconnect at any point in time during the use of the established computing environment <b>8920</b>′. In other embodiments, the mobile computing device <b>9005</b> may disconnect after the computing environment <b>8920</b>′ is terminated on the computing device <b>8910</b>. In still other embodiments, the user environment <b>8920</b>′ is automatically terminated upon disconnection of the mobile computing device <b>9005</b> from the computing device <b>8910</b>. In one embodiment, the computing environment <b>8920</b>′ may remain established on the computing device <b>8910</b> after the mobile computing device <b>9005</b> disconnects from the computing device <b>8910</b>. In some embodiments, once the computing environment <b>8920</b>′ is established on the computing device <b>8910</b>, the mobile computing device <b>9005</b> may be disconnected.

0464In some embodiments, the mobile computing device <b>9005</b> can access, read, and/or write user data <b>8930</b> to any portion of the portable computing environment <b>8920</b>. For example, in one embodiment, although the portable computing environment <b>8920</b> is not established or virtualized on computing device <b>8910</b>, the mobile computing device <b>9005</b> can still access, read, and/or write to and from the user data <b>8930</b>. In one embodiment, the user may use a first application in the established computing environment <b>8920</b>′ to access a file of the user data <b>8930</b>. In another embodiment, the user may use a second application on the mobile computing device <b>9005</b> to access the same file of the user data <b>8930</b>. In some embodiments, the virtualization software <b>8921</b> or virtual machine image <b>8925</b> allows access to the user data <b>8930</b>, even though virtualization software <b>8921</b> or virtual image <b>8925</b> is not executing or operating.

0465In some embodiments, the computing device <b>8910</b>, loading mechanism <b>8940</b>, or the virtualized layer <b>8920</b> provides a user interface for the user to select a portable computing environment from storage to establish the computing environment <b>8920</b>. For example, the mobile computing device <b>9005</b> or the computing device <b>8910</b> may have a portable computing environment selection mechanism, as discussed in greater detail below. In other embodiments, the computing device <b>8910</b>, loading mechanism <b>8940</b>, or the virtualized layer <b>8922</b> uses one of the plurality of portable computing environments based on a characteristic of the computing device <b>8910</b>, such as an operating system type, or based on user data identifying the portable computing environment to use for the computing device <b>8910</b>.

0466Referring now to <figref idref="DRAWINGS">FIG. 92A</figref>, in one embodiment, the computing device <b>8910</b> further comprises a computing environment selector <b>9250</b>. In brief overview, <figref idref="DRAWINGS">FIG. 92A</figref> depicts a mobile computing device <b>9005</b> connected to a computing device <b>8910</b> via a network <b>150</b>. The mobile computing device <b>9005</b> further comprises a storage element <b>128</b>, an I/O device or interface <b>130</b>, and a loading mechanism <b>8940</b>. The mobile computing device <b>9005</b> stores one or more portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n </i>in storage element <b>128</b>. In some embodiments, the storage element <b>128</b> comprises a storage device, such as the storage device <b>8905</b> described above in connection with <figref idref="DRAWINGS">FIGS. 90A and 90B</figref>.

0467In some embodiments, the mobile computing device <b>9005</b> does not have a user input I/O device <b>130</b> and/or a user output I/O device <b>130</b>. In other embodiments, the mobile computing device <b>9005</b> obtains or derives power from the connection to the computing device <b>8910</b>, such as for example, from a USB connection. In still other embodiments, the mobile computing device <b>9005</b> is a card of the following type: CompactFlash, Memory Stick, MultiMediaCard, Secure Digital, or SmartMedia.

0468In one embodiment, the storage element <b>128</b> stores a plurality of computing environments and a plurality of virtual machine images. In another embodiment, the storage element <b>128</b> stores one or more of a plurality of virtual machine images providing one of a different operating system or a different application than at least one virtual machine images accessible to the computing device. In still another of these embodiments, the storage element <b>128</b> stores one of the data associated with at least one computing environment and the at least one virtual machine image in an encrypted format.

0469In some embodiments, the mobile computing device <b>9005</b> stores data associated with at least one portable computing environment <b>8920</b>. In one of these embodiments, the mobile computing device <b>9005</b> stores data associated with a plurality of portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n</i>. In another of these embodiments, each of the portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n </i>comprises the same virtualization software <b>8921</b><i>a</i>-<b>8921</b><i>n</i>. In still another of these embodiments, the portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n </i>comprise different virtualization software <b>8921</b><i>a</i>-<b>8921</b><i>n. </i>

0470In other embodiments, the portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n </i>may comprise at least one virtualization software <b>8921</b><i>a </i>that is the same as another virtualization software <b>8921</b><i>b</i>. In other embodiments, the portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n </i>may comprise at least one virtualization software <b>8921</b><i>a </i>that is different from another virtualization software <b>8921</b><i>b</i>. In yet another embodiment, there may be one copy of the virtualization software <b>8921</b> to be used for each of the virtual images <b>8925</b><i>a</i>-<b>8925</b><i>n </i>in storage <b>128</b>.

0471In one embodiment, one or more of the virtual machine images <b>8925</b><i>a</i>-<b>8925</b><i>n </i>provides access to the same operating system or are used on the same operating system. In another embodiment, one or more of the virtual machine images <b>8925</b><i>a</i>-<b>8925</b><i>n </i>comprises a different operating system or executes on a different operating system. In some embodiments, the virtual machine images <b>8925</b><i>a</i>-<b>8925</b><i>n </i>share the same user data <b>8930</b>. In other embodiments, the virtual machine images <b>8925</b><i>a</i>-<b>8925</b><i>n </i>may each have distinct sets of user data <b>8930</b><i>a</i>-<b>8930</b><i>n</i>. In one embodiment, one of the virtual machine images <b>8925</b><i>a</i>-<b>8925</b><i>n </i>may provide access to a first computing environment, for example, a work desktop environment. In another embodiment, one of the virtual machine images <b>8925</b><i>a</i>-<b>8925</b><i>n </i>may provide access to a second computing environment, for example, a home desktop environment. In some embodiments, a virtual machine image <b>8925</b><i>a</i>-<b>8925</b><i>n </i>may provide access to a computing environment comprising a set of one or more portable applications of the user. The mobile computing device <b>9005</b> may store any desired set of one or more user environments <b>8920</b><i>a</i>-<b>8920</b><i>n. </i>

0472The mobile computing device <b>9005</b> includes a connector for connecting the mobile computing device <b>9005</b> to a computing device, such as the computing device <b>8910</b>. In one embodiment, the connector is connectable to a computing device <b>8910</b> via one of the following: a wireless connection, a USB connection, a Firewire connection, a Bluetooth connection, a Wi-Fi connection, a network connection, and a docking connection.

0473The mobile computing device <b>9005</b> includes a loading mechanism <b>8940</b> for automatically loading the at least one computing environment from the storage element onto a computing device upon connection of the mobile computing device to the computing device via the connector. In one embodiment, the loading mechanism <b>8940</b> automatically installs the at least one computing environment on the computing device <b>8910</b>. In another embodiment, the loading mechanism <b>8940</b> automatically executes the at least one computing environment on the computing device <b>8910</b>. In still another embodiment, the loading mechanism <b>8940</b> accesses at least one virtual machine image stored in the storage element <b>128</b> to execute a virtual machine, the virtual machine providing access to a computing environment.

0474In some embodiments, the mobile computing device <b>9005</b> includes a user interface provided for a user to select one virtual machine image to execute on the computing device <b>8910</b> from a plurality of virtual machine images. In other embodiments, the computing device <b>8910</b> provides the user interface.

0475In one embodiment, a selection mechanism, such as a computing environment selector <b>9250</b> provides a user interface for a user to select one of the portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n </i>to execute or establish on the computing device <b>8910</b>. The computing environment selector <b>9250</b> may comprise software, hardware, or any combination of software and hardware. In some embodiments, the computing environment selector <b>9250</b> has a graphical user interface providing a list of the one or more portable computing environment <b>8920</b><i>a</i>-<b>8920</b><i>n </i>stored in the mobile computing device <b>9005</b>. In other embodiments, the computing environment selector <b>9250</b> may comprise a command line interface. In one embodiment, the computing environment selector <b>9250</b> comprises software, stored on or provided by either the mobile computing device <b>9005</b> or the computing device <b>8910</b>. In one embodiment, the virtualized software <b>8921</b>, virtualized layer <b>8922</b> or portable computing environment <b>8920</b> comprises the computing environment selector <b>9250</b>. In another embodiment, the computing environment selector <b>9250</b> is executed on the mobile computing device <b>9005</b>. In some embodiments, the computing environment selector <b>9250</b> comprises a hardware and software mechanism on the mobile computing device <b>9005</b> for a user to select one of the portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n</i>. For example, the mobile computing device <b>9005</b> may provide via a screen or visual display unit a text based user interface with a thumb wheel to select a portable computing environment <b>8920</b><i>a</i>-<b>8920</b><i>n. </i>

0476Referring now to <figref idref="DRAWINGS">FIG. 92B</figref>, a flow diagram depicts another embodiment of the steps taken in a method for establishing a computing environment on a computing device via a mobile computing device. By connecting the mobile computing device <b>9005</b> carrying a portable computing environment <b>8920</b><i>a</i>-<b>8920</b><i>n </i>to a computing device <b>8910</b>, a user establishes a virtualized computing environment <b>8920</b>′ on the computing device <b>8910</b>. In brief overview, at step <b>9255</b>, the mobile computing device <b>9005</b> is connected to the computing device <b>8910</b>, and at step <b>9260</b>, the computing device <b>8910</b> detects the connection. At step <b>9265</b>, and in some embodiments, the user selects a portable computing environment <b>8920</b><i>a</i>-<b>8920</b><i>n </i>from storage to be used on the computing device <b>8910</b>. At step <b>9270</b>, a portable computing environment <b>8920</b><i>a</i>-<b>8920</b><i>n </i>in the storage element <b>128</b> is decrypted. At step <b>9275</b>, the virtualization software <b>8921</b> is automatically loaded on the computing device <b>8910</b>. At step <b>9280</b>, the computing device <b>8910</b> executes a virtual machine <b>8925</b>′ in the virtualized environment <b>8922</b> based on the portable computing environment <b>8920</b><i>a</i>-<b>8920</b><i>n</i>, such as by accessing virtual image <b>8925</b>. At step <b>9285</b>, the computing device <b>8910</b> controls access to the computing device <b>8910</b> via the virtualized computing environment <b>8920</b>′.

0477In further detail, at step <b>9255</b>, the mobile computing device <b>9005</b> is connected to the computing device <b>8910</b> by any suitable means and/or mechanisms. At step <b>9260</b>, the computing device <b>8910</b> detects the connection. In some embodiments, the operating system of the computing device <b>8910</b> detects connection of the mobile computing device <b>9005</b>. In other embodiments, a device manager detects the connection of the mobile computing device <b>9005</b>. In still other embodiments, a plug-and-play manager detects the connection of the mobile computing device <b>9005</b>. In other embodiments, a device driver for the computing device <b>8910</b> detects the connection. In yet another embodiment, the loading mechanism <b>8940</b>′ detects the connection of the mobile computing device <b>9005</b>.

0478In some embodiments, upon detection of the connection, the computing device <b>8910</b> may automatically install, load, and execute a device driver, software, application, process, service, thread or task to perform any of the operations described herein, as described above in connection with <figref idref="DRAWINGS">FIGS. 89A and 89B</figref>, <figref idref="DRAWINGS">FIGS. 90A and 90B</figref>, and <figref idref="DRAWINGS">FIGS. 91A and 91B</figref>. In other embodiments, upon detection of the connection, computing device <b>8910</b> may perform any type and form of authentication and authorization of the user of the mobile computing device <b>9005</b>.

0479At step <b>9265</b>, the user selects a portable computing environment <b>8920</b><i>a</i>-<b>8920</b><i>n </i>from storage element <b>128</b> to establish as the computing environment <b>8920</b>′ on the computing device <b>8910</b>. For example, the user may identify or select, via the computing environment selector <b>9250</b>, the portable computing environment <b>8920</b><i>a</i>-<b>8920</b><i>n </i>to run on the computing device <b>8910</b>. In one embodiment, the computing device <b>8910</b> displays a user interface providing a list of portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n </i>from the mobile computing device <b>9005</b> for the user to select to establish on the computing device <b>8910</b>. In some embodiments, the computing device <b>8910</b> executes an application program identified via the storage element <b>128</b> of the mobile computing device <b>9005</b>, such as via an autorun file. In another embodiment, the mobile computing device <b>9005</b> has a visual display unit displaying a user interface for the user to select one of the portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n</i>. In some embodiments, one of the portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n </i>is identified as a default computing environment <b>8920</b> to establish on the computing device <b>8910</b>. In another embodiment, the portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n </i>are identified in an order or preference or priority. In one embodiment, the mobile computing device <b>9005</b> comprises one portable computing environment <b>8920</b>. In this embodiment, the portable computing environment <b>8920</b> may not need to be selected by the user and is automatically used by the computing device <b>8910</b>. In another embodiment, although there is one portable computing environment <b>8920</b> on the mobile computing device <b>9005</b>, the user may select the one portable computing environment <b>8920</b>.

0480At step <b>9270</b>, the computing device <b>8910</b> may perform decryption on any portion of storage element <b>128</b> which may be encrypted. In one embodiment, the storage element <b>128</b> comprises an encrypted file system. In another embodiment, the virtualization software <b>8921</b>, virtual image <b>8925</b> and/or user data <b>8930</b>, or any portions thereof may be encrypted. In one embodiment, the computing device <b>8910</b>, decrypts the portion of storage <b>128</b> using a key via the loading mechanism <b>8940</b>′, the virtualization layer <b>8920</b>, or another set of executable instructions. In some embodiments, the key may a public key. In other embodiments, the key may be a private key. In one embodiment, the decryption key may be identity-based, such as based on the identity of a user authenticated via the computing device <b>8910</b>. In another embodiment, the user's authentication credentials, such as user id and/or password, may be used to generate or obtain a key for decryption. For example, the user's authentication credentials may be used to obtain a key stored in the database. In another embodiment, the computing device <b>8910</b> generates a private key based on performing an algorithm on the user's authentication credentials and a public key, such as a public key provided by a trusted third party. In yet another embodiment, the mobile computing device <b>9005</b> may store a key that is used by the computing device <b>8910</b> to authenticate the user and/or generate a decryption key. In some embodiments, the computing device <b>8910</b> uses a ticket authority to obtain a ticket for decrypting the encrypted portions of storage <b>128</b>. Any type and form of authentication technologies may be used in performing the operations described herein, such as password based authentication or biometric authentication. In one embodiment, a token is used to provide two-factor authentication, such as a token manufactured by RSA Security Inc. of Bedford, Mass.

0481At step <b>9275</b>, the computing device <b>8910</b> provides or establishes the virtualization layer <b>8922</b> on the host computing device <b>8910</b> as described above in connection with <figref idref="DRAWINGS">FIGS. 89A-89B</figref>, <figref idref="DRAWINGS">FIGS. 90A-90B</figref>, and <figref idref="DRAWINGS">FIGS. 91A-91B</figref>.

0482At step <b>9280</b>, the computing device <b>8910</b> automatically loads, executes or otherwise establishes a virtual machine <b>8925</b><i>a</i>-<b>8925</b><i>n </i>to provide access to a portable computing environment <b>8920</b><i>a</i>-<b>8920</b><i>n </i>on the virtualized layer <b>8922</b>. In one embodiment, the computing device <b>8910</b> and/or loading mechanism <b>8940</b> accesses the virtual machine image <b>8925</b><i>a</i>-<b>8925</b><i>n </i>from the storage element <b>128</b> and loads or executes the virtual machine image <b>8925</b><i>a</i>-<b>8925</b><i>n </i>as a virtual machine <b>8925</b>′ in the established virtualized environment <b>8922</b>. In another embodiment, the computing device <b>8910</b> loads, executes or establishes a virtual machine as described above in connection with <figref idref="DRAWINGS">FIGS. 89A-89B</figref>, <figref idref="DRAWINGS">FIGS. 90A-90B</figref>, and <figref idref="DRAWINGS">FIGS. 91A-91B</figref>.

0483At step <b>9285</b>, in some embodiments, the computing environment <b>8920</b>′ or virtual machine <b>8925</b> is established in a secured manner. In one embodiment, the established computing environment <b>8920</b>′ protects access to user data <b>8930</b> or portions of the computing environment <b>8920</b> from the environment of the computing device <b>8910</b> external to the computing environment <b>8920</b>′. In one embodiment, the virtualization software <b>8921</b> and/or virtualization layer <b>8922</b> ensures that contents of the virtual machine <b>8925</b>′ remain secure while running on the computing device <b>8910</b>. In some embodiments, the virtualization software <b>8921</b> and/or virtualization layer <b>8922</b> ensures that no input or no output is made available to the environment of the computing device <b>8910</b> in a persistent fashion. For example, in one embodiment, the virtualization software <b>8921</b> and/or virtualization layer <b>8922</b> may disable clipboard access between the host environment and the virtual machine <b>8925</b>′. In another embodiment, the virtualization software <b>8921</b> and/or virtualization layer <b>8922</b> disables access to a file system, or portion thereof, of the computing device <b>8910</b>. In other embodiments, the virtualization software <b>8921</b> and/or virtualization layer <b>8922</b> prevents paging by the virtual machine <b>8925</b>′ to the page file of the computing device <b>8910</b>. In one embodiment, the virtual machine <b>8925</b>′ uses the storage element <b>128</b> on the mobile computing device <b>9005</b> for file and data operations. In some embodiments, the virtualization layer <b>8922</b> acts as firewall between the virtual machine <b>8925</b>′ and the host environment. In yet another embodiment, the virtualization software <b>8921</b> and/or virtualization layer <b>8922</b> may provide a configuration mechanism, such as a user interface, to select which actions may be performed and/or data shared between the computing device <b>8910</b> and the virtual machine <b>8925</b>′.

0484Although this method is generally discussed as establishing a computing environment <b>8920</b>′ from one of a plurality of portable computing environments <b>8920</b><i>a</i>-<b>8920</b><i>n</i>, a plurality of computing environments <b>8920</b>′, <b>8920</b>″ may be established on the computing device <b>8910</b>. For example, a first computing environment <b>8920</b>′ may be established on the computing device <b>8910</b> using a first portable computing environment <b>8920</b><i>a </i>from the mobile computing device <b>9005</b>, and a second computing environment <b>8920</b>″ may be established on the computing device <b>8910</b> using a second portable computing environment <b>8920</b><i>b </i>from the mobile computing device <b>9005</b>.

0485Referring now to <figref idref="DRAWINGS">FIGS. 93A-93D</figref>, block diagrams depict embodiments of systems and methods for a mobile computing device to one or more hardware resources. The hardware resource may provide access to resources, such as a processor or memory with greater power, size, capacity or performance as compared to corresponding resources of the mobile computing device. <figref idref="DRAWINGS">FIG. 93A</figref> depicts an embodiment of a mobile computing device <b>9005</b> connecting to a docking station or device having a processor, memory and other computing resources for use by the mobile computing device. <figref idref="DRAWINGS">FIG. 93B</figref> depicts an embodiment of a mobile computing device connecting to a second hardware resource, via a docking mechanism, to use a processor, memory and/or resources of the second hardware resource. <figref idref="DRAWINGS">FIG. 93C</figref> depicts an embodiment of a docking station providing connectivity to a second hardware resource, such as a computing device, to use a processor, memory and/or resources of the second hardware resource. <figref idref="DRAWINGS">FIG. 93D</figref> depicts one embodiment of the steps taken in a method of providing to a mobile computing device one or more hardware resources, as described in the environments illustrated in <figref idref="DRAWINGS">FIGS. 93A-93C</figref>. In some embodiments, a portable computing environment may be established on the hardware resource in accordance with any of the systems and method described in conjunction with <figref idref="DRAWINGS">FIGS. 89A-89B</figref>, <b>90</b>A-<b>90</b>B, <b>91</b>A-<b>91</b>C, <b>92</b>A-<b>92</b>B. In other embodiments, the computing environment of the mobile computing device is accessed using the processor, memory, and/or resources of the hardware resource.

0486Referring now to <figref idref="DRAWINGS">FIG. 93A</figref>, in brief overview, the depicted system includes a mobile computing device <b>9005</b> connected to a hardware resource <b>9302</b>. The mobile computing device <b>9005</b> has a central processing unit <b>102</b>. The hardware resource <b>9302</b> has a central processing unit <b>102</b>′. In one embodiment, the hardware resource <b>9302</b> includes a docking station <b>9310</b> providing access to the hardware resource <b>9302</b>. In another embodiment, the docking station <b>9310</b> includes a processor <b>102</b>′ and memory <b>122</b>′. In still another embodiment, the mobile computing device provides the functionality of a mobile computing device <b>9005</b> as described above in connection with <figref idref="DRAWINGS">FIGS. 90A</figref>, <b>90</b>B, <b>91</b>A, <b>91</b>B, <b>92</b>A, and <b>92</b>B.

0487The mobile computing device <b>9005</b> comprises a connection mechanism <b>9305</b> for connecting the mobile computing device <b>9005</b> to the hardware resource <b>9302</b>. The mobile computing device <b>9005</b> uses the central processing unit <b>102</b> to effect an initial quanta of work and uses the central processing unit <b>102</b>′ of the hardware resource <b>9302</b> to effect subsequent quanta of work when connected to the hardware resource <b>9302</b>. In one embodiment, the mobile computing device <b>9005</b> uses the connection mechanism <b>9305</b> to switch to using the processing or computing capabilities of the hardware resource <b>9302</b> upon or after connecting to the hardware resource <b>9302</b>. For example, the mobile computing device <b>9005</b> may execute a computing environment <b>8920</b> on the hardware resource <b>9302</b> after connecting to the docking station <b>9310</b>.

0488In one embodiment, the mobile computing device <b>9005</b> connects to the hardware resource <b>9302</b> via connection across network <b>150</b>. In another embodiment, the mobile computing device <b>8905</b> is docked to the hardware resource <b>9302</b> via a I/O device mechanism <b>130</b><i>a</i>-<b>130</b><i>n </i>designed and constructed to connect to, and/or interface or communicate with the type and form of mobile computing device <b>9005</b>. In one embodiment, the mobile computing device <b>9005</b> is docked to the hardware resource <b>9302</b> via a docking connector. For example, one of the devices <b>9005</b> or <b>9310</b> may have a docking connector, and one of the device <b>9005</b> or <b>9310</b> may have a corresponding interface or connection mechanism designed to receive the connector.

0489The connection mechanism <b>9305</b> may comprise software, hardware, or any combination of software and hardware enabling the mobile computing device <b>9005</b> to access the hardware resource <b>9302</b>. In some embodiments, the connection mechanism <b>9305</b> comprises any type and form of integrated circuit, such as a Field Programmable Gate Array (FPGA), Programmable Logic Device (PLD), or Application Specific Integrated Circuit (ASIC) capable of performing any of the operations described herein.

0490In one embodiment, the connection mechanism <b>9305</b> comprises one of the following: a wireless connection, a USB connection, a Firewire connection, a Bluetooth connection, a Wi-Fi connection, a network connection, and a docking connection.

0491In some embodiments, the connection mechanism <b>9305</b> is enables the system or mother board of the mobile computing device <b>9005</b> to use a processor <b>102</b>′ and/or memory <b>122</b>′ of the hardware resource <b>9302</b>. In other embodiments, the connection mechanism <b>9305</b> communicates with any system or data bus of the mobile computing device <b>9005</b> to transmit and receive signals directing the mobile computing device <b>9005</b> to use a resource of the hardware resource <b>9302</b>, such as the processor <b>102</b>′ and memory <b>122</b>′ of the docking station <b>9310</b>. In some embodiments, the connection mechanism <b>9305</b> may communicate with a system or data bus of the hardware resource <b>9302</b> to enable the use of resources of the hardware resource <b>9302</b> by the mobile computing device <b>9005</b>.

0492In one embodiment, the connection mechanism <b>9305</b> may have the mobile computing device <b>9005</b> reboot, restart or reset when connected or docked to the hardware resource <b>9302</b>. In another embodiment, the connection mechanism <b>9305</b> may allow real-time switching to use a computing resource of the hardware resource <b>9302</b> without a reboot or restart. In some embodiments, the connection mechanism <b>9305</b> transfers data from memory <b>122</b> on the mobile computing device <b>9005</b> to memory <b>122</b>′ of hardware resource <b>9302</b>. In other embodiments, the connection mechanism <b>9305</b> transfers execution of a process from a processor <b>102</b> on the mobile computing device <b>9005</b> to processor <b>102</b>′ of the hardware resource <b>9302</b>. In still other embodiments, the mobile computing device <b>9005</b> transfers central processing control and management to the hardware resource <b>9302</b>. In yet other embodiments, the connection mechanism <b>9305</b> provides for the use of the processor <b>102</b> and/or memory <b>122</b> on the mobile computing device <b>9005</b> in conjunction with the processor <b>102</b>′ and/or memory <b>122</b>′ of the hardware resource <b>9302</b>. For example, when connected to the hardware resource <b>9302</b>, the mobile computing device <b>9005</b> may operate as a multi-processor device.

0493In some embodiments, the mobile computing device <b>9005</b> and/or connection mechanism <b>9305</b> maintains the state of the processor <b>102</b> and/or memory <b>122</b> on the mobile computing device <b>9005</b>. As such, in some of these embodiments, upon disconnection from the hardware resource <b>9302</b>, the mobile computing environment <b>9005</b> continues from a state prior to connection to the hardware resource <b>9302</b>. In others of these embodiments, the connection mechanism <b>9305</b> transfers data, information, and execution or control from a processor <b>102</b>′ and/or memory <b>122</b>′ to the processor <b>102</b> and/or memory <b>122</b> of the mobile computing device <b>9005</b>.

0494In one embodiment, the connection mechanism <b>9305</b> comprises any type and form of user interface to receive user input regarding connection to the hardware resource <b>9302</b>, use of hardware resources, and transfer of data and control between hardware resources. For example, the connection mechanism <b>9305</b> may display a graphical user interface upon docking to the hardware resource <b>9302</b> for the user to setup, configure, control and/or manage the use of the hardware resource <b>9302</b>.

0495In some embodiments, the hardware resource <b>9302</b> uses the storage element <b>128</b> of the mobile computing device <b>9005</b> to provide access to a computing environment. In one of these embodiments, the hardware resource <b>9302</b> executes an operating system stored in storage element <b>128</b> of the connected mobile computing device <b>9005</b>. In another of these embodiments, the hardware resource <b>9302</b> mounts the storage element <b>128</b> of the connected mobile computing device <b>9005</b> for access by the hardware resource <b>9302</b>. In still another of these embodiments, the user uses the operating system or computing environment of the hardware resource <b>9302</b> but executes applications and accesses data on the storage element <b>128</b> of the mobile computing device <b>9005</b>. In yet another of these embodiments, the mobile computing device <b>9005</b> may store portable applications to execute in the hardware resource <b>9302</b>.

0496In one embodiment, the hardware resource <b>9302</b> executes a virtual machine to provide access to a computing environment stored in the mobile computing device <b>9005</b>. In another embodiment, the hardware resource <b>9302</b> executes a virtual machine, the virtual machine providing access to a virtualized computing environment. In still another embodiment, a file from a storage location provided by the mobile computing device <b>9005</b> is accessed by a user via the hardware resource <b>9302</b> when the mobile computing device <b>9005</b> is connected to the hardware resource <b>9302</b>, and the file is accessed by the user, via the mobile computing device <b>9005</b>, when the mobile computing device <b>9005</b> is not connected to the hardware resource <b>9302</b>.

0497Still referring to <figref idref="DRAWINGS">FIG. 93A</figref> and in one embodiment, the hardware resource <b>9302</b> comprises a docking station <b>9310</b>, the docking station <b>9310</b> comprising a computer system <b>100</b>. In some embodiments, the docking station <b>9110</b> may be any type and form of computer system <b>100</b>, as described above in connection with <figref idref="DRAWINGS">FIGS. 1A-1B</figref>. In one of these embodiments, and as described in connection with <figref idref="DRAWINGS">FIGS. 1A-1B</figref>, the docking station <b>9110</b> may comprise components including, but not limited to, a processor <b>102</b>′, memory <b>122</b>, storage <b>128</b>, a network interface <b>118</b>′, and/or one or more I/O devices <b>130</b><i>a</i>-<b>130</b><i>n</i>′. In another of these embodiments, the docking station <b>9110</b> is connected to a display device <b>124</b>, a keyboard <b>126</b>, and/or a pointing device <b>127</b>. The docking station <b>9310</b> may also be connected to or provide access to other hardware resources and computing peripherals. In some embodiments, the docking station <b>9310</b> provides access to resources of another computer system <b>100</b> via a network <b>150</b>.

0498In one embodiment, the hardware resource <b>9302</b> has a processor <b>102</b>′ having a higher processor speed than the processor <b>102</b> of the mobile computing device <b>9005</b>. In another embodiment, the hardware resource <b>9302</b> has a processor <b>102</b>′ comprising a processor architecture different than a processor architecture of the processor <b>102</b> of the mobile computing device <b>9005</b>. In still another embodiment, the mobile computing device <b>9005</b> uses the processor <b>102</b> to effect an initial quanta of work and, upon connection to the hardware resource <b>9302</b> via the connection mechanism <b>9305</b>, uses the processor <b>102</b>′ to effect a subsequent quanta of work. In yet another embodiment, the mobile computing device <b>9005</b> determines that a memory <b>122</b>′ of the hardware resource <b>9302</b> has a memory size larger than a memory size of a memory <b>122</b> of the mobile computing device <b>9005</b> and uses the memory <b>122</b>′ of the hardware resource <b>9302</b> to effect subsequent quanta of work.

0499In some embodiments, the mobile computing device <b>9005</b> uses a first operating system executing on the first central processing unit when not connected to the hardware resource and a second operating system executing on the second central processing unit when connected to the hardware resource. In one of these embodiments, the second operating system is different than the first operating system.

0500Referring now to <figref idref="DRAWINGS">FIG. 93B</figref>, another embodiment of the hardware resource <b>9302</b> and the mobile computing device <b>9005</b> is depicted. In brief overview, the mobile computing device <b>9005</b> connects to a docking station <b>9310</b> across a network <b>150</b>, and in turn, docking station <b>9310</b> connects to a computing device <b>8910</b>. In this embodiment, the hardware resource <b>9302</b> includes a docking station <b>9310</b> connected to or in communication with a computing device <b>8910</b>. Instead of providing resources, such as a processor <b>102</b>′ and memory <b>122</b>′ as depicted in <figref idref="DRAWINGS">FIG. 93A</figref>, the docking station <b>9310</b> provides access to resources of a second computing device <b>8910</b> via the connection across network <b>150</b>′. In one embodiment, after connection to the docking station <b>9310</b>, the mobile computing device <b>9005</b> uses resources of the computing device <b>8910</b> via connections across networks <b>150</b> and <b>150</b>′.

0501Referring now to <figref idref="DRAWINGS">FIG. 93C</figref>, another embodiment of the hardware resource <b>9302</b> and the mobile computing device <b>9005</b> is depicted. In brief overview, the mobile computing device <b>9005</b> connects to the computing device <b>8910</b> via docking mechanism <b>9310</b>. In this embodiment, the hardware resource <b>9302</b> includes a computing device <b>8910</b> having a docketing mechanism <b>9310</b>, such as an I/O device or mechanism <b>130</b>, to dock the mobile computing device <b>9005</b>. After connection via docking mechanism <b>9310</b>, the mobile computing device <b>9005</b> uses the resources of the computing device <b>8910</b>, such as a processor and/or memory. In some embodiments, the hardware resource <b>9302</b> provides access the mobile computing device <b>9005</b> with access to a peripheral computing device.

0502In any of the embodiments depicted in <figref idref="DRAWINGS">FIGS. 93A-93C</figref>, the hardware resource <b>9302</b> may provide resources and capabilities offering improved power, performance, or other operating or performance characteristics desired by the user of the mobile computing device <b>8905</b> or suitable for one or more applications of the mobile computing device, as described in more detail above in connection with <figref idref="DRAWINGS">FIGS. 89A-89B</figref>, <b>90</b>A-<b>90</b>B, <b>91</b>A-<b>91</b>B, and <b>92</b>A-<b>92</b>B.

0503Referring now to <figref idref="DRAWINGS">FIG. 93D</figref>, a flow diagram depicts one embodiment of the steps taken in a method for providing to a mobile computing device one or more hardware resources. In brief overview, the mobile computing device uses a first central processing unit of the mobile computing device <b>9005</b> to effect an initial quanta of work (step <b>9355</b>). The mobile computing device <b>9005</b> connects to a hardware resource <b>9302</b> including a second central processing unit (step <b>9360</b>). The mobile computing device uses a second central processing unit of the hardware resource <b>9302</b> to effect subsequent quanta of work (step <b>9365</b>).

0504A mobile computing device uses a first central processing unit to effect an initial quanta of work (step <b>9355</b>). In one embodiment, the mobile computing device is a computer <b>100</b> as described above in connection with <figref idref="DRAWINGS">FIGS. 1A and 1B</figref>. In another embodiment, the mobile computing device is a mobile computing device <b>9005</b> as described above in connection with <figref idref="DRAWINGS">FIGS. 90A-92B</figref>.

0505The mobile computing device <b>9005</b> connects to a hardware resource <b>9302</b> including a central processing unit (step <b>9360</b>). In one embodiment, the mobile computing device <b>9005</b> connects to the hardware resource <b>9302</b> by any suitable means and/or mechanisms. In some embodiments, the mobile computing device <b>8905</b> connects or docks to a docking station <b>9310</b> providing one or more resources. In one of these embodiments, the mobile computing device <b>9005</b> connects to a docking station <b>9310</b> having a processor <b>102</b>′ and/or memory <b>122</b>′. In another of these embodiments, the mobile computing device <b>9005</b> connects to a docking station <b>9310</b> providing a connection to a second computing device <b>8910</b>, the second computing device <b>8910</b> including a processor <b>102</b>′. In still another of these embodiments, the mobile computing device <b>9005</b> connects or docks to a docking mechanism <b>9310</b> of a host computing device <b>8910</b>.

0506In some embodiments, the mobile computing device <b>8905</b> and the docking station <b>9110</b> may connect via any type and form of connection, wired, wireless or otherwise, including, but not limited to, via a wireless connection, a Wi-Fi connection, a USB connection, a Firewire connection, a Bluetooth connection, a network connection, and a docking connection. The mobile computing device <b>8905</b> and docking station <b>9110</b> may communicate via any type and form of protocol, such as a device, bus, communication, application, data, or network protocol.

0507The mobile computing device <b>9005</b> uses a central processing unit of the hardware resource <b>9302</b> (step <b>9370</b>). In one embodiment, the mobile computing device <b>9005</b> initiates use of a processor <b>102</b>′ and/or memory <b>122</b>′ of the hardware resource <b>9302</b> via a connection mechanism <b>9305</b>. In another embodiment, the mobile computing device <b>9005</b> transfers execution control and management to the central processing unit of the hardware resource <b>9302</b>. In still another embodiment, the mobile computing device <b>9005</b> transfers data and information to the processor and/or memory of the hardware resource <b>9302</b>. In some embodiments, the mobile computing device <b>9005</b> uses the processor and/or memory of the hardware resource <b>9302</b> as a second processor and/or memory for the mobile computing device <b>9005</b>.

0508In one embodiment, the mobile computing device <b>9005</b> connects to a hardware resource <b>9302</b> comprising one of the following: a first docking station having the second central processing unit; a second computing device having the second central processing unit; and a second docking station providing access to a third computing device having the second central processing unit.

0509In some embodiments, an application program on the mobile computing device <b>9005</b> executes in the processor <b>102</b>′ and uses memory <b>122</b>′ of the computing environment <b>9102</b> and displays on a visual display unit of the mobile computing device <b>9005</b>. In other embodiments, an application program executing on the processor and using the memory of the hardware resource <b>9302</b> receives user input from an input device of the mobile computing device <b>9005</b>. In still other embodiments, an application program executing on the processor and using the memory of the hardware resource <b>9302</b> displays on a display device <b>124</b> of the hardware resource <b>9302</b> while receiving input from an input mechanism of the mobile computing device <b>9005</b>.

0510In one embodiment, an application program executing on the processor and using the memory of the hardware resource <b>9302</b> displays on a visual display unit of the mobile computing environment <b>9005</b> while receiving input from an input device of the hardware resource <b>9302</b>, such as keyboard <b>126</b> and pointing device <b>127</b>. In some embodiments, the computing environment of mobile computing device <b>9005</b> executes on the processor and memory of the mobile computing device <b>9005</b> but also uses a resource of the hardware resource <b>9302</b>, such as a network connection, printer, display device, input device, or any I/O device <b>120</b>.

0511In one embodiment, the mobile computing device <b>9005</b> determines that the second central processing unit has a processor speed greater than a processor speed of the first central processing unit and uses the second central processing unit of the hardware resource to effect subsequent quanta of work. In another embodiment, the mobile computing device <b>9005</b> determines that the second central processing unit has a processor architecture different than a processor architecture of the first central processing unit and uses the second central processing unit of the hardware resource to effect subsequent quanta of work. In still another embodiment, the mobile computing device <b>9005</b> identifies a memory of the mobile computing device <b>9005</b> and identifies a second memory of the hardware resource <b>9302</b>. In yet another embodiment, the mobile computing device <b>9005</b> determines that the second memory of the hardware resource has a memory size larger than a memory size of the first memory of the mobile computing device and uses the second memory of the hardware resource to effect subsequent quanta of work.

0512In some embodiments, the hardware resource <b>9302</b> uses one or more resources of the mobile computing device <b>9005</b>. In one of these embodiments, the hardware resource <b>9302</b> accesses a storage element or storage device of the mobile computing device <b>9005</b>, such as the storage element <b>128</b>. In some embodiments, the hardware resource <b>9302</b> mounts the storage element <b>128</b>. In another of these embodiments, the hardware resource <b>9302</b> boots or reboots or otherwise establishes an environment based on a computing environment stored on the mounted storage element <b>128</b>. In still another of these embodiments, the hardware resource <b>9302</b> uses the processor <b>102</b> and/or memory <b>122</b> of the mobile computing device <b>9005</b> in addition to the processor and/or memory of the hardware resource <b>9302</b>.

0513In some embodiments, the hardware resource <b>9302</b> uses a display device and/or input device of the mobile computing device <b>9005</b>. In other embodiments, the hardware resource <b>9302</b> executes a computing environment <b>8920</b>′ based on a portable computing environment <b>8920</b> in the storage element <b>128</b> of the mobile computing device <b>9005</b>. In some embodiments, the portable computing environment <b>8920</b> may execute in the hardware resource <b>9302</b> but display on and receive input from the mobile computing device <b>9005</b>.

0514In one embodiment, the hardware resource <b>9302</b> provides the mobile computing device <b>9005</b> with access to a peripheral computing device of the hardware resource. In another embodiment, the mobile computing device <b>9005</b> uses a first operating system executing on the first central processing unit on the mobile computing device <b>9005</b> when not connected to the hardware resource <b>9302</b> and a second operating system executing on the second central processing unit of the hardware resource <b>9302</b> when connected to the hardware resource <b>9302</b>. In still another embodiment, the first operating system is different than the second operating system. In yet another embodiment, a virtual machine executing on the hardware resource <b>9302</b> provides the mobile device <b>9005</b> with access to a first operating system. In some embodiments, the hardware resource <b>9302</b> executes a virtual machine to provide access to a computing environment stored in the mobile computing device <b>9005</b>. In other embodiments, the mobile computing device <b>9005</b> provides access to a computing environment on the hardware resource <b>9302</b>. In still other embodiments, a user accesses, via the hardware resource <b>9302</b>, a file stored in the mobile computing device <b>9005</b> when the mobile computing device <b>9005</b> is connected to the hardware resource <b>9302</b> and accessing, by the user, via the mobile computing device <b>9005</b>, the file stored in the mobile computing device <b>9005</b> when the mobile computing device <b>9005</b> is not connected to the hardware resource <b>9302</b>.

0515In one embodiment, the mobile computing device <b>9005</b> uses a processor of the hardware resource <b>9302</b> to provide access to a computing environment stored on the mobile computing device <b>9005</b>. In another embodiment, the mobile computing device <b>9005</b> uses a processor of the hardware resource <b>9302</b> to provide access to an operating system stored on the mobile computing device <b>9005</b>. In still another embodiment, the mobile computing device <b>9005</b> uses a processor of the hardware resource <b>9302</b> to provide access to an application program stored on the mobile computing device <b>9005</b>. In yet another embodiment, the mobile computing device <b>9005</b> uses a processor of the hardware resource <b>9302</b> to execute a virtual machine on the hardware resource, responsive to a virtual machine image stored on the mobile computing device. In some embodiments, the mobile computing device uses a processor of the hardware resource <b>9302</b> to provide access to a computing environment stored on the hardware resource.

0516Referring now to <figref idref="DRAWINGS">FIG. 94A</figref>, a block diagram depicts one embodiment of a mobile computing device having a plurality of processors. In brief overview, mobile computing device <b>9005</b> comprises a first processor <b>102</b> and a second processor <b>102</b>′. The processors <b>102</b>, <b>102</b>′ may access a memory <b>122</b> and/or storage element <b>128</b> on the mobile computing device <b>9005</b>. The mobile computing device <b>9005</b> includes a switching mechanism <b>9405</b> for switching between using the first processor <b>102</b> and the second processor <b>102</b>′. In some cases, the mobile computing device <b>9005</b> may have a lower-powered processor <b>102</b> for minimal functionality or standby operations, and have a higher-powered processor <b>102</b> for normal operations or for applications suitable or requiring more powerful processor capability. While mobile, the user may want to access features such as email, calendar, and contact information much like a PDA or smartphone. When accessing such applications, the mobile computing device <b>9005</b> may use the lower-powered processor <b>102</b> to lengthen battery-life and conserve power. The user may at any time want to access an application having higher processor requirements or suitability. When accessing these applications, the mobile computing device <b>9005</b> may use the higher-powered processor <b>102</b>′.

0517In further detail, the processor <b>102</b> and processor <b>102</b>′ may be the same type and speed of processor. In other embodiments, the processor <b>102</b> and processor <b>102</b>′ may be a different type and speed of processor. In some embodiments, processor <b>102</b> comprises a processing speed and/or capability greater than processor <b>102</b>′. In other embodiments, processor <b>102</b>′ comprises a processing speed and/or capability greater than the processor <b>102</b>. In some embodiments, the processor <b>102</b> and <b>102</b>′ are single core processors. In other embodiments, the processor <b>102</b> and <b>102</b>′ are multiple core processors. In one embodiment, the processor <b>102</b> is a single core processor and processor <b>102</b>′ is a multiple core processor, such as dual or quad core processor. In yet another embodiment, the processors <b>102</b> and <b>102</b>′ comprise the same processor architecture and/or are manufactured by the same processor manufacturer. In other embodiments, the processors <b>102</b> and <b>102</b>′ comprise different processor architectures and/or are manufactured by different processor manufacturers.

0518In some embodiments, a first processor <b>102</b> comprises operational characteristics designed and constructed for lower power consumption, longer battery life, performance and/or applications of a mobile or portable computing device. In one of these embodiments, a first processor <b>102</b> may be referred to as a low-powered CPU. In other embodiments, a second processor <b>102</b>′ comprises operational characteristics designed and constructed for the power, performance and/or application requirements of a desktop computing environment, server computing environment, or otherwise a non-mobile computing environment. In one of these embodiments, the second processor <b>102</b>′ may be referred to as a high-powered CPU. In other embodiments, the processor <b>102</b> provides a first level of processing or processor capability, and the second processor <b>102</b>′ provides a second level of processing or processor capability. In one of these embodiments, the second level of capability is greater or higher than the first level. In another of these embodiments, the second level of capability is preferred over the first level. In still other embodiments, the mobile computing device uses the first processor for one or more applications suitable for the first level of power consumption and processing capability, and the mobile computing device uses the second processor for one or more applications suitable for the second level of power consumption and processing capability.

0519The switching mechanism <b>9405</b> enables the mobile computing device <b>9005</b> to switch between using a first processor <b>102</b> and a second processor <b>102</b>′, or any plurality of processors. In some embodiments, the switching mechanism <b>9405</b> comprises any type and form of integrated circuit, such as a Field Programmable Gate Array (FPGA), Programmable Logic Device (PLD), or Application Specific Integrated Circuit (ASIC) capable of performing any of the operations described herein. In some embodiments, the switching mechanism <b>9405</b> enables the system or mother board of the mobile computing device <b>9005</b> to use a first processor <b>102</b>. In some embodiments, the switching mechanism <b>9405</b> enables the system or mother board of the mobile computing device <b>8905</b> to use a second processor <b>102</b>′. In one embodiment, the switching mechanism <b>9405</b> communicates with any system or data bus of the mobile computing device <b>9005</b> to transmit and/or receive signals directing the mobile computing device <b>9005</b> to use a second processor <b>102</b>′ instead of a first processor <b>102</b>, and likewise to use the first processor <b>102</b> instead of the second processor <b>102</b>′. In some embodiments, the switching mechanism <b>9405</b> may interface and/or communicate with a system or data bus of the mobile computing device <b>9005</b> to transmit and/or receive signals to use both the first processor <b>102</b> and second processor <b>102</b>′ instead of just the first processor <b>102</b> or the second processor <b>102</b>′.

0520In another embodiment, the switching mechanism <b>9405</b> transfers data and execution from processor <b>102</b> to processor <b>102</b>′ of the mobile computing device <b>9005</b>. In some embodiments, the switching mechanism <b>9405</b> transfers central processing control and management from a first processor <b>102</b> to a second processor <b>102</b>′, or from the second processor <b>102</b>′ to the first processor <b>102</b>. In one embodiment, the switching mechanism <b>9405</b> may have the mobile computing device <b>9005</b> reboot, restart or reset when switching between using a processor <b>102</b>, <b>102</b>′. In another embodiment, the switching mechanism <b>9405</b> may perform real-time switching from processor to processor.

0521In some embodiments, the switching mechanism <b>9405</b> identifies a condition, event or trigger upon which to switch between using one processor and another processor. In other embodiments, switching mechanism switches to one of the first processor or the second processor based on a user selection. In one of these embodiments, the switching mechanism <b>9405</b> comprises a user interface, such as a graphical user interface or a command line user interface, for a user to identify, specify or configure the conditions, events or triggers for performing switching between processors. For example, the switching mechanism <b>9405</b> may switch, automatically, manually or otherwise, between a first processor <b>102</b> and a second processor <b>102</b>′ based on any operational characteristics of the mobile computing device <b>9005</b> or the processors <b>102</b>, <b>102</b>′. In still other embodiments, the switch mechanism <b>9105</b> switches between use of a processor based on a level of load of the first processor or second processor. In yet other embodiments, the switch mechanism <b>9405</b> switches between use of a processor based on a level of activity, such as task, processes, applications, of the first processor <b>102</b> or second processor <b>102</b>′. In some embodiments, the switch mechanism <b>9405</b> switches between using a first processor and a second processor based on a level of consumption of power and/or battery life. In still another embodiment, the switch mechanism <b>9405</b> switches between use of a processor based on a type of application actuated or executed on the mobile computing device <b>9005</b>.

0522In another embodiment, the switching mechanism <b>9405</b> comprises a user interface for the user to switch between processors <b>102</b>, <b>102</b>′. For example, using a hot key, set of key strokes, or selecting an icon in a task bar, a user may instruct, command or direct the mobile computing device <b>9005</b> and/or switching mechanism <b>9405</b> to switch between processors, use one processor instead of another, or use the plurality of processors <b>102</b>, <b>102</b>′ at the same time.

0523Referring now to <figref idref="DRAWINGS">FIG. 94B</figref>, a flow diagram depicts one embodiment of a method for switching, by a mobile computing device, between use of multiple processors. In brief overview, the mobile computing device uses a first processor designed and constructed to provide a first level of power consumption and processing capability (step <b>9455</b>). The switching mechanism determines to switch the mobile computing device to using a second processor based on an operating characteristic of the mobile computing device, the second processor designed and constructed to provide a second level of power consumption and processing capability (step <b>9460</b>). The mobile computing device <b>9005</b> uses the second processor responsive to the determination by the switching mechanism.

0524In further detail, the mobile computing device <b>9005</b> uses the first processor (step <b>9455</b>). In one embodiment, the switching mechanism <b>9405</b> identifies the first processor <b>120</b> as the default processor for use by the mobile computing device <b>9005</b>. In another embodiment, the mobile computing device <b>9005</b> uses the first processor <b>120</b> upon starting, restarting or booting of the operating system on the mobile computing device <b>9005</b>. In some embodiments, a user selects the first processor <b>120</b> as the default processor. In one of these embodiments, the use may have identified the first processor <b>120</b> to the switching mechanism <b>9405</b>.

0525The switching mechanism <b>9405</b> determines to switch the mobile computing device <b>9005</b> to using the second processor <b>120</b>′, based on an operating characteristic of the mobile computing device, the second processor designed and constructed to provide a second level of power consumption and processing capability (step <b>9460</b>). In some embodiments, the switching mechanism <b>9405</b> determines to switch based on operating conditions or characteristics of the mobile computing device <b>9005</b>, such as the operating system, resource usage, memory usage, power consumption, load, and numbers of processes, applications, services or tasks.

0526In one embodiment, the second level of power consumption and processing capability of the second processor comprises a level greater than the first level of power consumption and processing capability of the first processor. In another embodiment, the mobile computing device uses the first processor for one or more applications suitable for the first level of power consumption and processing capability, and uses the second processor for one or more applications suitable for the second level of power consumption and processing capability. In still another embodiment, the switching mechanism <b>9405</b> switches to one of the first processor or the second processor automatically based on the initiation of execution of an application.

0527In some embodiments, the switching mechanism <b>9405</b> switches to one of the first processor or the second processor automatically based on one or more of the following operating characteristics: a level of load of one of the first processor or the second processor, a level of activity of one of the first processor or the second processor, and a level of power consumption of one of the first processor or the second processor. In one of these embodiments, the switching mechanism <b>9405</b> determines the load, activity or power consumption of the first processor <b>102</b> is near, equal or greater than the processing capability of the first processor <b>102</b>. In another of these embodiments, the switching mechanism <b>9405</b> determines the processor requirements of an application executed by the user or requested by the user for execution is near, equal or greater than the processing capability of the first processor <b>102</b>.

0528In other embodiments, the switching mechanism <b>9405</b> determines the mobile computing device <b>9005</b> would perform at a more suitable performance or operational level, or in a manner desired by the user if the mobile computing device <b>9005</b> was using the second level of processing capability of the second processor <b>120</b>′. In still other embodiments, a user selects to switch to using the second processor <b>120</b>′. In one of these embodiments, a user, via a user interface, directs or instructs the switching mechanism <b>9405</b> to switch the mobile computing device <b>9005</b> to use the second processor <b>120</b>′.

0529The mobile computing device <b>9005</b> uses the second processor <b>120</b> (step <b>9465</b>). In one embodiment, the mobile computing device <b>9005</b> uses the second processor <b>120</b>′ instead of the first processor <b>120</b>. In another embodiment, the mobile computing device <b>9005</b> uses the second processor <b>120</b>′ in addition to the first processor <b>120</b>. In some embodiments, the mobile computing device <b>9005</b> and/or switching mechanism <b>9405</b> transfers information, data, control and/or management to the second processor <b>120</b>′ to continue operation of the operating system, applications, process, services or tasks executing on the first processor <b>102</b>. In other embodiments, new applications or processes initiated by the user are executed on the second processor <b>120</b>′.

0530In some embodiments, the switching mechanism <b>9405</b> switches to having the mobile computing device <b>9005</b> use the first processor <b>120</b> for a first level of processing capability. As with step <b>9460</b>, the switching mechanism <b>9405</b> determines to switch based on the operating conditions or characteristics of the device <b>9005</b>, such as the operating system, resource usage, memory usage, power consumption, load, and numbers of processes, applications, services or tasks. For example, in one embodiment, the switching mechanism <b>9405</b> determines the load, activity or power consumption of the second processor <b>102</b>′ is greater than the processing capability needed for operating the mobile computing device <b>9005</b> in its current state. In another embodiment, the switching mechanism <b>9405</b> determines the processor requirements of an application executed by the user or requested by the user for execution is near, or equal to the processing capability of the first processor <b>102</b>. In some embodiments, the switching mechanism <b>9405</b> determines the processor requirements of an application executed by the user or requested by the user for execution is less than the second level of processing capability of processor <b>120</b>′. In other embodiments, the switching mechanism <b>9405</b> determines the mobile computing device <b>9005</b> would perform at a suitable performance or operational level, or in a manner desired by the user if the mobile computing device <b>9005</b> was using the first level of processing capability of the first processor <b>120</b>. For example, the mobile computing device <b>9005</b> would perform in a suitable manner for the user using the first processor <b>102</b> but would also save on battery life or reduce power consumption. In yet another embodiment, a user selects to switch to using the first processor <b>120</b>. For example, in one embodiment, the user via a user interface directs or instructs the switching mechanism <b>9405</b> to switch the mobile computing device <b>9005</b> to use the first processor <b>120</b>. The method <b>9450</b> may be performed again to switch the mobile computing device <b>9005</b> to using the first processor at step <b>9455</b>.

0531Referring still to <figref idref="DRAWINGS">FIG. 8</figref>, in some embodiments, the session management component <b>1300</b> uses a connection to transmit information associated with a monitor on the client machine <b>10</b> to the virtual machine service component. In one of these embodiments, multi-monitor geometry support is provided. In another of these embodiments, the session management component <b>1300</b> accesses multi-monitor information and enables the virtual machine service component to create a version of the multi-monitor information in the virtual machine.

0532In one embodiment, techniques are provided for virtualizing a display environment of a client by modifying and controlling the behavior and appearance of an application's window based on a desired display layout for the client. The techniques may be used for simulating or providing a multiple display setup for a single display environment. One embodiment provides a window processing mechanism to intercept a selected message to a window of an application and modify the message to the window to display the window on the client based on the desired display layout. The message to the window provides for the behavior or appearance of a window used or displayed by the application. In one embodiment, the window processing mechanism provides a hooking mechanism to an application's window procedure and replaces the original window procedure with a window procedure designed to intercept a selected window message and modify values of arguments or parameters of the intercepted window message based on the desired display layout of the client. As such, selected window messages are processed to provide or translate the behavior or appearance of the window to the desired display layout.

0533The techniques and mechanisms described may be practiced in a server-based computing environment, such as between a client machine <b>10</b> and a remote machine <b>30</b> communicating via a remote display protocol. A remote machine <b>30</b>, or a virtual machine executing in a hypervisor on the remote machine <b>30</b>, may be setup or configured for a single display environment while the client machine <b>10</b> may be setup or configured for one or more display devices. For example, a session on a machine, such as a session on a WINDOWS server operating system may only be able to be configured or setup for a single display. The server may obtain a preferred or desired display layout for the client, and store the display layout in association with the client, such as associating the display layout with a remote session for the client. The window message processing mechanism may be used by the server to intercept and modify selected messages to windows of the application running on the server on behalf of the client. The window messages are modified to provide a behavior or appearance of the window based on the display layout associated with the client. As such, the display output communicated by the server to the client includes display output to be displayed on the client according to the client's display layout rather than the display layout, e.g., single display layout, of the session on the server.

0534Using the techniques and mechanisms described herein allows a user to access a remotely available application in a server-based computing environment regardless of the monitor layout of the client. Instead of the server associating a single display with the remote session, the server will provide display output based on the client's display layout. Furthermore, remotely-provided application may maximize to the proper display from the perspective of the client. Also, menu items and other windows of an application may be displayed appropriately within an application, for example, without appearing disjoint from the application. Additionally, the issue of a window being rendered off-screen after changes to the display layout is handled by automatically moving the window to a viewable upon detection of an off-screen window.

0535Furthermore, these techniques and mechanisms may also be practiced in a local computing environment to virtualize, simulate, or otherwise provide a multiple monitor environment for a client having a single display device. Although the client may have a single display device, a desired display layout may be configured or provided to specify multiple displays. The window processing mechanism may be used to intercept and modify window messages for an application on the client to control the behavior or appearance of the window based on the desired display layout instead of the actual monitor layout. As such, a user may gain the functionality, benefits, and advantages of a multiple monitor environment without having multiple display devices.

0536Referring now to <figref idref="DRAWINGS">FIG. 15A</figref>, one embodiment of an environment <b>1502</b> is depicted. In brief overview, a client machine <b>10</b>, may be connected to or otherwise use a display device <b>124</b>, in one embodiment, or multiple display devices <b>124</b><i>a</i>-<b>124</b><i>n</i>, in another embodiment. The client machine <b>10</b> includes a display layout <b>1520</b> comprising a desired display configuration for the client machine <b>10</b>, such as for display device <b>124</b>. The client machine <b>10</b> includes a storage element <b>1525</b> for storing the display layout of the client machine <b>10</b>. The client machine <b>10</b> also includes a window processing mechanism <b>1550</b>.

0537In further detail, the display layout <b>1520</b> comprises any type and/or form of information or data to identify, specify, or describe a desired display layout configuration for the client. In one embodiment, the display layout <b>1520</b> may comprise a file or set of files in any format. In another embodiment, the display layout <b>1520</b> may comprise any information or data stored in any type and/or form of storage or memory element provided by the client machine <b>10</b>. In an additional embodiment, the display layout <b>1520</b> may be provided or stored in any suitable type and/or form of database. In further embodiments, the display layout <b>1520</b> may be provided via any object, data structure, or application programming interface (API). The display layout <b>1520</b> may comprise any graphical, textual, or combination of graphical and textual elements. The display layout <b>1520</b> may be created, edited, configured, or otherwise provided by any suitable means and/or mechanisms, such as a graphical and/or text-based tool, program or application. In one embodiment, a graphical tool with a user interface may be used to design, create, edit and configure the display layout <b>1520</b>.

0538The display layout <b>1520</b> may include attributes, properties, characteristics, values, settings, profiles, and other display configuration information <b>1522</b><i>a</i>-<b>1522</b><i>n </i>to define each display for the client. The display layout <b>1520</b> may include display configuration <b>1522</b><i>a</i>-<b>1522</b><i>n </i>for each of the desired displays, physical, virtual, or otherwise. In some embodiments, the display layout <b>1520</b> includes a description of the layout, location, position, organization, or arrangement for each display device <b>124</b><i>a</i>-<b>124</b><i>n</i>. In one embodiment, the display layout <b>1520</b> includes a visual or graphical arrangement identifying the location and/or size of each monitor with respect to each other. In some embodiments, each display <b>1522</b><i>a</i>-<b>1522</b><i>n </i>is identified by an identifier, such as a name or number. Also, the display configuration <b>1522</b><i>a</i>-<b>1522</b><i>n </i>may include a monitor type, a screen refresh rate, adapter type, adapter information, screen resolution, a color quality, a color scheme, a font size, a background, a style for buttons and menus, and a screen saver.

0539Additionally, the display configuration <b>1522</b><i>a</i>-<b>1522</b><i>n </i>may include information or data to identify or specify a resolution <b>1524</b><i>a</i>-<b>1524</b><i>n </i>and/or a work area <b>1526</b><i>a</i>-<b>1526</b><i>n </i>for each display, such as the display corresponding to a display device <b>124</b><i>a</i>-<b>124</b><i>n</i>. In one embodiment, the resolution <b>1524</b><i>a</i>-<b>1524</b><i>n </i>identifies the number of pixels, or individual points of color, contained on a display monitor, expressed in terms of the number of pixels on the horizontal axis and the number of pixels on the vertical axis. As those ordinarily skilled in the art will appreciate, the sharpness of the image displayed on the display device <b>124</b><i>a</i>-<b>124</b><i>n </i>may depend on the resolution and the size of the display device <b>124</b><i>a</i>-<b>124</b><i>n</i>. In another embodiment, the work area <b>1526</b><i>a</i>-<b>1526</b><i>n </i>identifies the usable dimensions of the screen area of the display device <b>124</b><i>a</i>-<b>124</b><i>n </i>in pixels. In some embodiments, the work area <b>1526</b><i>a</i>-<b>1526</b><i>n </i>does not include the dimensions of the screen area not useable by the user, such as the portion of the screen area having a menu, tool, or task bar, such as the task bar on a desktop provided via a WINDOWS operating system.

0540In one embodiment, the display layout <b>1520</b> is configured to correspond to the number of display devices <b>124</b><i>a</i>-<b>124</b><i>n</i>, and their available features and characteristics, accessible by the client. In other embodiments, the display layout <b>1520</b> does not match or correspond to the number of display devices <b>124</b><i>a</i>-<b>124</b><i>n </i>connected to the client. For example, the client machine <b>10</b> may have a single display device <b>124</b><i>a </i>but the display layout <b>1520</b> may be configured for multiple display devices <b>124</b><i>a</i>-<b>124</b><i>n</i>. In one aspect, the display layout <b>1520</b> may be configured for a display device <b>124</b><i>a </i>that is virtual, or a virtual display device. A virtual display device is rendered off the screen area of the physical display device <b>124</b><i>a </i>and may be placed on and off the visible screen area by any suitable mechanism and/or means, such as for example, tabbing between desktops, or panning and scrolling beyond the work area of the physical display device <b>124</b><i>a</i>. A virtual display device may comprise a resolution <b>1524</b><i>a</i>-<b>1524</b><i>n</i>, a work area <b>1526</b><i>a</i>-<b>1526</b><i>n</i>, and any other data or information in a display configuration <b>1522</b><i>a</i>-<b>1522</b><i>n </i>as if it was a physical display device <b>1524</b><i>a</i>-<b>1524</b><i>n </i>connected or to be connected to a client machine <b>10</b>.

0541In some embodiments, the work area <b>1526</b><i>a</i>-<b>1526</b><i>n </i>of the virtual display device is relative to and/or adjacent horizontally or vertically to the screen area of the physical display device <b>124</b><i>a</i>-<b>124</b><i>n</i>. In other embodiments, the resolution <b>1524</b><i>a</i>-<b>1524</b><i>n </i>of the virtual display device is the same resolution <b>1524</b><i>a</i>-<b>1524</b><i>n </i>of the physical display device <b>124</b><i>a</i>, or one of the resolutions <b>1524</b><i>a</i>-<b>1524</b><i>n </i>supported by the physical display device <b>124</b><i>a</i>. In some embodiments, a display <b>1522</b><i>a </i>corresponding to a physical display device <b>124</b><i>a </i>is not required to be configured as the top left monitor. In other embodiments, the display layout <b>1520</b> may comprise any arrangement of positive and/or negative coordinate systems, and any displays <b>1522</b><i>a</i>-<b>1522</b><i>n</i>, or display devices <b>124</b><i>a</i>-<b>124</b><i>n</i>, virtual or otherwise, may be configured to be located with any positive and/or negative coordinates, or in any portion of the positive and/or negative coordinate system.

0542The storage element <b>1525</b> illustrated in the client machine <b>10</b> of <figref idref="DRAWINGS">FIG. 15A</figref> may comprise any type and/or form of storage or memory, such as random-access memory, a disk drive, a disk array, a rewriteable optical drive, shared memory, a database, a file, an object, a data structure, or any other type and/or form of storage or memory element that allows the storing of and access to information or data, such as the display layout <b>1520</b>. In one embodiment, storage element <b>1525</b> provides the display layout <b>1520</b> as a globally mapped data file, which may be accessible by any of the applications <b>1530</b> of the client machine <b>10</b>. In some embodiments, the storage element <b>1525</b> stores the display layout <b>1520</b>, or a portion of the display layout <b>1520</b>. In other embodiments, the display layout <b>1520</b> may be converted, translated, transformed or otherwise altered to be stored in the storage element <b>1525</b>. Although the storage element <b>1525</b> is illustrated on the client machine <b>10</b>, another client machine <b>10</b> accessible to the client machine <b>10</b>, such as a server, may have a storage element for storing the display layout <b>1520</b>.

0543In some embodiments, the client machine <b>10</b> executes or otherwise provides one or more applications <b>1530</b>. The application <b>1530</b> can be any type and/or form of software, program, or executable instructions such as any type and/or form of web browser, web-based client, client-server application, a thin-client computing client, an ActiveX control, or a Java applet, or any other type and/or form of executable instructions capable of executing on client machine <b>10</b>. In some embodiments, the application <b>1530</b> provides one or more windows <b>1535</b><i>a</i>-<b>1535</b><i>n</i>, also sometimes collectively referenced herein as <b>1535</b>. In one embodiment, the window <b>1535</b><i>a</i>-<b>1535</b><i>n </i>is a graphic, sometimes rectangular in shape, having either some kind of user interface or graphical or textual representation of the output of, and in some cases, allowing input for the application <b>1530</b>. In another embodiment, the window <b>1535</b><i>a</i>-<b>1535</b><i>n </i>comprises an area on the screen that displays information, including user documents as well as communications such as alert boxes and dialog boxes. Additionally, the user may open or close a window, move it around on the display, and sometimes change its size, scroll through it, and edit its contents.

0544In one embodiment, the user interface for the application <b>1530</b> is the window <b>1535</b><i>a</i>-<b>1535</b><i>n</i>. In other embodiments, the application <b>1530</b> provides a top level window <b>1535</b><i>a</i>-<b>1535</b><i>n </i>for the presentation and/or navigation structure or framework for the application <b>1530</b>, and provides additional windows <b>1535</b><i>a</i>-<b>1535</b><i>n </i>in response to input or other events. For example, the application <b>1530</b> may have a menu system and screen area for a user interface represented by a top level window <b>1535</b><i>a</i>, and based on user input, displays a secondary or smaller window <b>1535</b> to provide output to the user and/or receive input from the user regarding the application <b>1530</b>.

0545The application <b>1530</b>, and/or any windows <b>1535</b><i>a</i>-<b>1535</b><i>n </i>of the application may receive a message <b>1540</b>, such as a window message, as input. The message <b>1540</b> may be any type and/or form of communication via any type and/or form of medium. In some embodiments, the message <b>1540</b> comprises a communication to a window <b>1535</b><i>a</i>-<b>1535</b><i>n </i>to control or direct the behavior, appearance, attributes, or properties of the window <b>1535</b><i>a</i>-<b>1535</b><i>n</i>. In an exemplary embodiment of a WINDOWS-based environment, the application <b>1530</b> is event-driven, and waits for the operating system, or system, to pass input to them. The system passes all input for an application to the various windows <b>1535</b><i>a</i>-<b>1535</b><i>n </i>in the application <b>1530</b>. Each window <b>1535</b><i>a</i>-<b>1535</b><i>n </i>has a function, called a window procedure, which the operating system calls in response to receiving input for the window. A window procedure is a function that receives and processes all messages sent to the window. A window class may have a window procedure, and every window created with that class uses that same window procedure to respond to messages. The window procedure processes the input and returns control to the system. The system passes input to a window procedure in the form of a message <b>1540</b>, which may be generated by the operating system or other applications <b>1530</b>. A message <b>1540</b> may be generated for an input event, for example, when the user types, moves the mouse, or clicks a control such as a scroll bar. A message <b>1540</b> may also be generated in response to changes in the operating system or computing device brought about by an application <b>1530</b>. An application <b>1530</b> can generate messages to direct windows <b>1535</b><i>a</i>-<b>1535</b><i>n </i>of the application <b>1530</b> to perform tasks or to communicate with windows <b>1535</b><i>a</i>-<b>1535</b><i>n </i>in other applications.

0546In the exemplary embodiment of a WINDOWS-based system, a message <b>1540</b> is sent to a window procedure with parameters. In one embodiment, the message <b>1540</b> comprises a set of four parameters: a window handle, a message identifier, and two values referred to as message parameters. The window handle identifies the window for which the message is intended, and is used to determine which window procedure should receive the message. A message identifier identifies a purpose or function of the message <b>1540</b>. When a window procedure receives a message, it uses the message identifier to determine how to process the message. For example, a message identifier WM_PAINT of a message <b>1540</b> may indicate to a window procedure that the window's <b>1535</b> client area has changed and must be repainted. The parameters of a message <b>1540</b> may specify data or the location of data used by a window procedure when processing a message <b>1540</b>. The meaning and value of the parameters may depend on the message <b>1540</b>. A message parameter can include an integer, a string, packed bit flags, a pointer to a structure containing additional data, or any type and/or form of data or information.

0547Although a message <b>1540</b> is generally described in the context of a WINDOWS-based environment, a message <b>1540</b> may be any type and/or form of communication in any type of operating system or environment, as one ordinarily skilled in the art would recognize and appreciate, to control or direct the appearance, behavior and attributes of a window <b>1540</b> being displayed or otherwise being used, processed, or provided by the application <b>1530</b>. As such, the message <b>1540</b> may be in a form and have content suitable to the environment or operating system for which the operations described herein may be practiced.

0548Still referring to <figref idref="DRAWINGS">FIG. 15A</figref>, the window processing mechanism <b>1550</b>, also referred to as a window message processing mechanism, provides the means and mechanism for changing, controlling or directing an appearance, behavior or attribute of the window <b>1535</b><i>a</i>-<b>1535</b><i>n </i>of an application <b>1530</b> based on the desired display layout <b>1520</b> of the client <b>1505</b>. The window processing mechanism <b>1550</b> may comprise an application programming interface (API), application, module, software component, library, service, process, task or any other form and/or type of executable instructions designed to and capable of executing or providing the functionality described herein. The window processing mechanism <b>1550</b> may comprise software, hardware, or any combination of software and hardware. In some embodiments, an application <b>1530</b> may be designed or constructed to include the functionality of the window processing mechanism <b>1550</b>, while in some other embodiments, the window processing mechanism <b>1550</b> is designed and constructed to be used by existing applications <b>1530</b>, for example, without changing the application <b>1530</b>.

0549In one embodiment, the window processing mechanism <b>1550</b> comprises a mechanism for subclassing window procedures of a window <b>1535</b> of the application <b>1530</b>, and providing a window procedure that gets called or used in place of the original window procedure of the window <b>1535</b>.

0550In one embodiment, a hooking mechanism is used by the window processing mechanism <b>1550</b> to provide the replacement window procedure. In some embodiments, a hooking mechanism comprises using an application programming interface (API) to replace the executable instructions or code of a function, procedure, or API with a desired set of executable instructions or code. For example, the window processing mechanism <b>1550</b> may introduce a hooking mechanism for any API related to creating, establishing, or providing a window <b>1535</b>, for example, the CreateWindowA, CreateWindowW, CreateWindowExA, and CreateWindowExW APIs of the WINDOWS operating system environment. In some embodiments, the window procedure is replaced via the Windows application programming interface (API) calls of GetWindowLong and SetWindowLong. In other embodiments, the replaced window procedure is stored in a list of any suitable type and/or form along with a window handle or reference to the replaced window procedure. As such, the window procedure used by the window processing mechanism <b>1550</b> may call the replaced window procedure. For example, the window processing mechanism <b>1550</b> may pass through a message <b>1540</b> to the original window procedure for processing.

0551The window procedure of the window processing mechanism <b>1550</b> may be constructed and designed to intercept all or a portion of the messages <b>1540</b> communicated to or received by the window <b>1535</b>. In some embodiments, the window procedure intercepts all messages <b>1540</b> and any messages <b>1540</b> not to be modified are communicated to the original or replaced window procedure. In one embodiment of a Microsoft® Windows based environment, the window procedure of the window processing mechanism <b>1550</b> intercepts messages <b>1540</b> with a message identifier comprising one of the following: 1) WM_DISPLAYCHANGE, 2) WM_WINDOWPOSCHANGED, 3) WM_WINDOWPOSCHANGING, and 4) WM_GETMAXMININFO. A WM_DISPLAYCHANGE message <b>1540</b> communicates to a window <b>1535</b> a change in a resolution <b>1524</b> of a display <b>124</b>. A WM_WINDOWPOSCHANGED message <b>1540</b> communicates to a window <b>1535</b> a change in a size, position, or a place in the Z order for the window <b>1540</b>. A WM_WINDOWPOSCHANGING message <b>1540</b> is communicate to a window <b>1535</b> when a change in a size, position, or a place in the Z order for the window <b>1540</b> is about to occur. A WM_GETMAXMININFO message <b>1540</b> is communicated to a window <b>1535</b> when a size or position, or a window <b>1540</b> is about to change.

0552The window processing mechanism <b>1550</b> intercepts a message <b>1540</b> and modifies a return value or parameter of the message <b>1540</b> to correspond to or be based on the display layout <b>1520</b>. In some embodiments, the window processing mechanism <b>1550</b> intercepts messages <b>1540</b> for a top-level window <b>1535</b>, and in other embodiments, the window processing mechanism <b>1550</b> intercepts messages for windows <b>1535</b> that are not a top-level window. In further embodiments, the window processing mechanism <b>1550</b> intercepts messages <b>1540</b> for a certain set of windows <b>1540</b>. For example, the window processing mechanism <b>1550</b> may be configured to intercept windows <b>1550</b> defined in a list, database, storage <b>1525</b>, or any other type and/or form of configuration medium.

0553The message <b>1540</b> intercepted by the window processing mechanism <b>1550</b> may have return values, arguments, and/or parameters designed or targeted for the actual display layout of the client machine <b>10</b> or remote machine <b>30</b>, but the window processing mechanism <b>1550</b> changes the return values, arguments and/or parameters to be designed or targeted for the display configuration <b>1522</b><i>a</i>-<b>1522</b><i>n </i>provided by the desired display layout <b>1520</b>. The window processing mechanism <b>1550</b> may read, access, acquire or otherwise obtain the display layout <b>1520</b> from the storage element <b>1525</b> by any suitable means and/or mechanism. The window processing mechanism <b>1550</b> may comprise any type of logic, functionality, business rules, or operations to obtain the values, arguments, and parameters of the message <b>1540</b> and analyze, compare or otherwise process the values, arguments, and parameters of the message <b>1540</b> in view of the display layout <b>1520</b>, and determine any changes or modifications to the values, arguments or parameters or the message <b>1540</b> to display the window <b>1535</b> on a display identified by the display layout <b>1520</b>. The window processing mechanism <b>1550</b> modifies the message <b>1540</b> according to the determined changes and communicates the message <b>1540</b> to the window <b>1535</b>. In some embodiments, the window processing mechanism <b>1550</b> determines the message <b>1540</b> does not need to be modified and thus communicates the message <b>1540</b> in the same form as intercepted by the window processing mechanism <b>1550</b>. In other embodiments, the window processing mechanism <b>1550</b> replaces the message <b>1540</b> with a second message.

0554Referring now to <figref idref="DRAWINGS">FIG. 15B</figref>, another embodiment of a networked computer environment is shown in which the client machine <b>10</b> communicates with a remote machine <b>30</b> via one or more communication networks <b>150</b>. The client machine <b>10</b> may be connected to or otherwise use one or more display devices <b>124</b><i>a</i>-<b>124</b><i>n</i>. The client machine <b>10</b> includes a display layout <b>1520</b> comprising a desired display configuration for the client machine <b>10</b>, such as for display devices <b>124</b><i>a</i>-<b>124</b><i>n</i>. The client machine <b>10</b> may also include a client agent <b>1508</b>. The remote machine <b>30</b> includes an application <b>1530</b> providing one or more windows <b>1535</b><i>a</i>-<b>1535</b><i>n</i>, and a storage element <b>1525</b> for storing the display layout <b>1520</b> of the client machine <b>10</b>. The remote machine <b>30</b> also includes a server agent <b>1528</b>, a session login mechanism <b>1545</b>, and a window processing mechanism <b>1550</b>.

0555The environment <b>1500</b> may provide a server-based or thin-client computing environment for practicing the operations described herein. For example, the application <b>1530</b> may be an application executed on the remote machine <b>30</b> on behalf of the client machine <b>10</b>. The display output from execution of the application <b>1530</b> may be communicated to the client machine <b>10</b> for display on the client, for example, via the client agent <b>1508</b>. The display output may be communicated between the remote machine <b>30</b> and client machine <b>10</b> via a remote display protocol. The display output may be based on a window <b>1540</b> of the application <b>1530</b> running on the remote machine <b>30</b> but to be displayed on the client machine <b>10</b>. As will be described in further detail below, the window processing mechanism <b>1550</b> on the remote machine <b>30</b> intercepts and modifies messages <b>1540</b> of the application <b>1530</b> running on the remote machine <b>30</b>, communicates the message <b>1540</b> to the window <b>1535</b>. As such, the display output communicated to the client machine <b>10</b> reflects the modified message <b>1540</b> processed by the window <b>1535</b>.

0556In one embodiment, as shown in <figref idref="DRAWINGS">FIG. 15B</figref>, a client agent <b>1508</b> is included within the client machine <b>10</b>. The client agent <b>1508</b> can be, for example, implemented as a software program and/or as a hardware device, such as, for example, an ASIC or an FPGA. An example of a client agent <b>1508</b> with a user interface is a Web Browser (e.g. Internet Explorer and/or Netscape™ Navigator browser). The client agent <b>1508</b> can use any type of protocol, such as a remote display protocol, and it can be, for example, an HTTP client agent, an FTP client agent, an Oscar client agent, a Telnet client agent, an Independent Computing Architecture (ICA) client agent from Citrix Systems, Inc. of Fort Lauderdale, Fla., or a Remote Desktop Protocol (RDP) client agent from Microsoft Corporation of Redmond, Wash. In some embodiments, the client agent <b>1508</b> is configured to connect to the remote machine <b>30</b>. In some embodiments (not shown), the client <b>1508</b> includes a plurality of client agents <b>1508</b>, each of which may communicate with a remote machine <b>30</b>, respectively.

0557Additionally, the remote machine <b>30</b> may comprise a server agent <b>1528</b> which may be capable of and configured to work in conjunction with the client agent <b>1508</b>. For example, the server agent <b>1528</b> may be a server side component that accepts connections and requests from the client agent <b>1508</b>. In another embodiment, the server agent <b>1528</b> may be capable of and configured to accept or establish remote access connections or sessions for the client machine <b>10</b>. In one embodiment, the client agent <b>1508</b> and server agent <b>1528</b> may communicate using a protocol, such as http, ICA or RDP, over the network <b>1504</b>. In some embodiments, the client agent <b>1508</b> and/or server agent <b>1528</b> are used to establish, re-establish, maintain, or otherwise provide a server-based computing or thin-client computing based connection or session. In another embodiment, the client agent <b>1508</b> and the server agent <b>1528</b> establish the start and end points of communications for a connection between the client machine <b>10</b> and the destination remote machine <b>30</b>.

0558In some embodiments, the remote machine <b>30</b> includes a storage element <b>1525</b> for storing the display layout. In one embodiment, storage element <b>1525</b> provides the display layout <b>1520</b> as a globally mapped data file, which may be accessible by any of the applications <b>1530</b> of the remote machine <b>30</b>. In some embodiments, the display layout <b>1520</b> is stored in the same form as provided to or received by the remote machine <b>30</b>. Although the storage element <b>1525</b> is illustrated on the remote machine <b>30</b> in <figref idref="DRAWINGS">FIG. 15B</figref>, the client machine <b>10</b> may also include a storage element <b>1525</b>′, and in some embodiments, the client machine <b>10</b> stores the display layout <b>1520</b> in the client's storage element <b>1525</b>′, and/or to the remote machine's storage element <b>1525</b>.

0559The remote machine <b>30</b> may also include a session login mechanism <b>1545</b>, which may include any type and/or form of service, process, task or program, application, or executable instructions on the remote machine <b>30</b> to handle and process login or session requests. The session login mechanism <b>1545</b>, or any portion thereof, may be provided via the operating system of the remote machine <b>30</b>. In one embodiment, the session login mechanism <b>1545</b> includes the windows logon process, winlogon, a component of the Microsoft® Windows families of operating systems. As such, the session login mechanism <b>1545</b> may provide interactive logon support, and may include a Graphical Identification and Authentication dynamically linked library (DLL) referred to as the GINA, and any number of network providers. The session login mechanism <b>1545</b> may include any interfaces, such as an application programming interface (API) or dynamically linked libraries, i.e., a dll, to allow any resource, application, network or network provide gather obtain any identification and authentication information during a logon process.

0560The session login mechanism <b>1545</b> may perform an authentication process and password-updating operations for the operating system and/or for one or more resources, programs, applications, networks, or network providers. In one embodiment, the session login mechanism <b>1545</b> provides authentication services for the operating system, and in additional embodiments, also provides authentication services for access to applications <b>1530</b> to be executed on the remote machine <b>30</b> on behalf of the client machine <b>10</b>, such as in a server-based or thin-client computing model. Additionally, the session login mechanism <b>1545</b> may monitor any mouse and/or keyboard activity related to logging on or secure access of the remote machine <b>30</b>, or any resource, application, network, or network provider. In some embodiments, the session login mechanism <b>1545</b> may establish any initial services, processes, or tasks for a user or session on the remote machine <b>30</b>.

0561The remote machine <b>30</b> may execute or otherwise provide one or more applications <b>1530</b>. The application <b>1530</b> can be any type and/or form of software, program, or executable instructions such as any type and/or form of web browser, web-based client, client-server application, a thin-client computing client, an ActiveX control, or a Java applet, or any other type and/or form of executable instructions capable of executing on client machine <b>10</b> or communicating via a network <b>1504</b>. The application <b>1530</b> can use any type of protocol and it can be, for example, an HTTP client, an FTP client, an Oscar client, or a Telnet client. In some embodiments, the application <b>1530</b> uses a remote display or presentation level protocol. In other embodiments, the application <b>1530</b> comprises any type of software related to Voice-Over-Internet Protocol (VoIP) communications, such as a soft IP telephone. In further embodiments, the application <b>1530</b> comprises any application related to real-time data communications, such as applications for streaming video and/or audio. In some embodiments, the application <b>1530</b> provides one or more windows <b>1535</b><i>a</i>-<b>1535</b><i>n</i>, also sometimes collectively referenced herein as <b>1535</b>.

0562In some embodiments, the remote machine <b>30</b> or a machine farm <b>38</b> may be running one or more applications <b>1530</b>, such as an application <b>1530</b> providing a thin-client computing or remote display presentation application. In one embodiment, the remote machine <b>30</b> or machine farm executes as an application <b>1530</b>, any portion of the Citrix Access Suite™ by Citrix Systems, Inc., such as the MetaFrame or Citrix Presentation Server™, and/or any of the Microsoft® Windows Terminal Services manufactured by the Microsoft Corporation. In one embodiment, the application <b>1530</b> is an ICA client, developed by Citrix Systems, Inc. of Fort Lauderdale, Fla. In other embodiments, the application <b>1530</b> includes a Remote Desktop (RDP) client, developed by Microsoft Corporation of Redmond, Wash.

0563Additionally, the remote machine <b>30</b> may run an application <b>1530</b>, which for example, may be an application server providing email services such as Microsoft Exchange manufactured by the Microsoft Corporation of Redmond, Wash., a web or Internet server, or a desktop sharing server, or a collaboration server. In some embodiments, any of the applications <b>1530</b> may comprise any type of hosted service or products, such as GoToMeeting™ provided by Citrix Online Division, Inc. of Santa Barbara, Calif., WebEx™ provided by WebEx, Inc. of Santa Clara, Calif., or Microsoft Office LiveMeeting provided by Microsoft Corporation of Redmond, Wash.

0564Although in <figref idref="DRAWINGS">FIG. 15A</figref> and <figref idref="DRAWINGS">FIG. 15B</figref>, the window processing mechanism <b>1550</b> is illustrated as included in the application <b>1530</b>, the window processing mechanism <b>1550</b> may reside in any portion of the remote machine <b>30</b>, the client machine <b>10</b>, and/or external to the application <b>1530</b>, for example, as illustrated in <figref idref="DRAWINGS">FIG. 15C</figref>. In one embodiment, the window processing mechanism <b>1550</b> comprises a service, process, or task that runs in a system context or with the system privileges of the operating system. In some embodiments, the windows processing mechanism <b>1550</b> may monitor messages <b>1540</b> communicated to windows <b>1535</b><i>a</i>-<b>1535</b><i>n </i>of an application <b>1530</b>, and intercept and modify the message <b>1540</b> to the windows <b>1535</b><i>a</i>-<b>1535</b><i>n</i>. One ordinarily skilled in the art will recognize and appreciate that the windows processing mechanism <b>1550</b> may comprise any type and/or form of executable instructions capable of performing the operations described herein.

0565In another embodiment of illustrated in <figref idref="DRAWINGS">FIG. 15C</figref>, the session login mechanism <b>1545</b> may be used to provide for, or use, any of the functionality of the window processing mechanism <b>1550</b>. In some embodiments, the session login mechanism <b>1545</b> may read, access, acquire or otherwise obtain the display layout <b>1520</b> from the storage element <b>1525</b>. In other embodiments, the session login mechanism <b>1545</b> accesses, loads, or uses the functionality of the window processing mechanism <b>1550</b> via a dynamically loaded library, such as a library provided via a network provider to the winlogon process of a WINDOWS operating system. In other embodiments, the session login mechanism interfaces with or communicates to the window processing mechanism <b>1550</b> to provide the techniques described herein. In further embodiments, the session login mechanism <b>1545</b> may use the techniques described herein during reconnection, re-establishment, and/or re-authentication of a login or user session, such as a remote session in a server-based computing environment <b>1500</b>.

0566In another aspect, techniques for virtualizing a display environment of a client machine <b>10</b> by controlling or directing the appearance, behavior and attributes of a window <b>1535</b> of an application <b>1530</b> based on the desired display layout <b>1520</b> for a client machine <b>10</b> are described. In view of the systems and structure of the environments <b>1500</b>, <b>1501</b>, and <b>1502</b> depicted in <figref idref="DRAWINGS">FIGS. 15A-15C</figref>, the operations, functionality, and techniques will be addressed by the methods depicted in <figref idref="DRAWINGS">FIGS. 3A-3D</figref>. <figref idref="DRAWINGS">FIG. 3A</figref> depicts a method <b>300</b> for practicing an embodiment using the window processing mechanism <b>1550</b>. <figref idref="DRAWINGS">FIG. 3B</figref> depicts examples of window messages and processing used in conjunction with the method <b>300</b>. <figref idref="DRAWINGS">FIG. 3C</figref> depicts a method <b>350</b> for practicing an embodiment when reconnecting, re-establishing or re-authenticating via the session login mechanism <b>1545</b>. <figref idref="DRAWINGS">FIG. 3D</figref> depicts illustrative method <b>360</b> for changing the client's display layout <b>1520</b>, for example, during execution of an application <b>1530</b>.

0567Referring now to <figref idref="DRAWINGS">FIG. 16A</figref>, in brief overview, one embodiment of a method for providing a desired display layout <b>1520</b> of the client machine <b>10</b> is shown. At step <b>1610</b>, and at step <b>1615</b>, the display layout <b>1520</b> is stored in the storage element <b>1525</b>, and the display layout <b>1520</b> is associated with the client <b>1505</b>. At step <b>1620</b>, the window processing mechanism <b>1550</b> accesses the display layout <b>1520</b> from the storage element <b>225</b> to obtain the desired display layout information for the client machine <b>10</b>. At step <b>1625</b>, the window processing mechanism <b>1550</b> intercepts messages <b>1540</b> to a window <b>1535</b> displayed on a client machine <b>10</b> by an application <b>1530</b>. At step <b>1630</b>, the window processing mechanism <b>1550</b> modifies the message <b>1540</b> to provide the window <b>1535</b> on the client machine <b>10</b> based on the desired display layout <b>1520</b> for the client machine <b>10</b>. At step <b>1635</b>, the window <b>1535</b> is displayed on the client machine <b>10</b> based on the modified message <b>1540</b>. As such, the appearance and behavior of the window <b>235</b> is translated to and based on the display layout <b>1520</b>.

0568In further detail, at step <b>1610</b> of the method, the desired display layout <b>120</b> for the client is provided. In one embodiment, the display layout <b>120</b> is communicated from the client machine <b>10</b> to the remote machine <b>30</b>. For example, the client machine <b>10</b> establishes a connection or communication session with the remote machine <b>30</b>. In some cases, the remote machine <b>30</b> requests the display layout <b>1520</b> from the client machine <b>10</b>, and the client <b>1505</b> communicates the display layout <b>1520</b> in response to the request. In another embodiment, the display layout <b>1520</b> is communicated via the session login mechanism <b>1545</b> during a logon or authentication process, and in some embodiments, upon a re-logon or re-authentication process. In one embodiment, the display layout <b>1520</b> is stored in a database and queried by the client machine <b>10</b> or remote machine <b>30</b> to obtain the display layout <b>1520</b>. In other embodiments, the display layout <b>1520</b> is downloaded, by either the client machine <b>10</b> or the remote machine <b>30</b> from a web server, a web-site, an application server, another remote machine <b>30</b>′ or via the Internet. In further embodiments, a user may configure the display layout <b>1520</b> with a program, application, or tool, and store the display layout <b>1520</b> on a client machine <b>10</b>, remote machine <b>30</b>, or another client machine <b>10</b>.

0569At step <b>1615</b>, the display layout <b>1520</b> is stored in the storage element <b>1525</b>, and associated with the client machine <b>10</b>. In some embodiments, the remote machine <b>30</b> receives the display layout <b>1520</b> from the client machine <b>10</b> and stores the display layout <b>1520</b> in the storage element <b>1525</b>. In one embodiment, the remote machine <b>30</b> stores the display layout <b>1520</b> as a globally mapped data file on the remote machine <b>30</b> accessible by one or more applications <b>1530</b>. In another embodiment the remote machine <b>30</b> stores the display layout <b>1520</b> to another client machine <b>10</b> accessible to the remote machine <b>30</b>, such as via the network <b>1504</b>. In some embodiments, the client machine <b>10</b> stores the display layout <b>1520</b> to a storage element <b>1525</b> on the remote machine <b>30</b>, to a storage element <b>1525</b> on the client machine <b>10</b>, or to a storage element <b>1525</b> accessible via the network <b>1504</b> or via the Internet.

0570The display layout <b>1520</b> may be stored to the storage element <b>1525</b> in any form suitable to the storage element <b>1525</b>, and may be converted, transformed, altered, translated or otherwise processed for storage in the storage element <b>1525</b>. For example, in one embodiment, the display layout <b>1520</b> may comprise data, such as a file, on the client machine <b>10</b> transmitted via network packets to the remote machine <b>30</b>, and then translated into a globally mapped data file on the remote machine <b>30</b>. In another embodiment, the display layout <b>1520</b> is stored into any type and/or form of database <b>1525</b>, such as a relational database. In other embodiments, the display layout <b>1520</b> is stored in storage <b>1525</b> comprising memory. For example, the display layout <b>1520</b> may comprise or be represented by any type of object, data structure, or portion of memory on the client machine <b>10</b> and/or remote machine <b>30</b>.

0571The display layout <b>1520</b> may be associated with the client machine <b>10</b> by any suitable means and/or mechanisms. In one embodiment, the name, or any portion thereof, of the globally mapped data file may identify the client machine <b>10</b>. In another embodiment, any portion of content of the globally mapped data file may identify the client machine <b>10</b>. In additional embodiments, the client machine <b>10</b> or remote machine <b>30</b> may use any type of object, data structure, process, or other elements in memory to associate the display layout <b>1520</b> with the client machine <b>10</b>. In other embodiments, the client machine <b>10</b> or remote machine <b>30</b> may use portions of the storage element <b>1525</b> or other types of storage, such as another file, to associate the display layout <b>1520</b> with the client.

0572The window processing mechanism <b>1550</b>, at step <b>1620</b> of illustrative method <b>300</b>, accesses the display layout <b>1520</b> from the storage element <b>1525</b> to obtain the desired display layout information for the client machine <b>10</b>. In one embodiment, the executable instructions of the window procedure used by the window processing mechanism <b>1550</b> comprises instructions to load, read, or otherwise acquire the display layout <b>1520</b>. For example, the window processing mechanism <b>1550</b> may perform any type and/or forms of file input/output, i.e., file I/O, operations to read a globally mapped data file having the display layout <b>1520</b>. In another embodiment, the instructions of the hooking application programming interface (API) for the window processing mechanism <b>1550</b> provides instructions for obtaining the display layout <b>1520</b>. In another embodiment, the application <b>1530</b> reads or accesses the display layout <b>1520</b>, for example, upon execution or start up. In some embodiments, the application <b>1530</b> may be executed during a session, such as a user or remote session. In one embodiment, the globally mapped data file <b>1525</b> may only be accessible by an application <b>1530</b> associated with or available via the remote session. In further embodiments, access to the globally mapped data file may have access locked by a mutex or semaphore, which is global for the remote session. One ordinarily skilled in the art will recognize and appreciate that any type and/or form of locking mechanism can be used to control access the storage element <b>1525</b>, such as a globally mapped data file.

0573At step <b>1625</b>, the window processing mechanism <b>1550</b> intercepts messages <b>1540</b> to a window <b>1535</b> displayed on a client machine <b>10</b> by an application <b>1530</b>. In one embodiment, upon obtaining the display layout <b>1520</b> a hooking mechanism is introduced into the remote machine <b>30</b> or the application <b>1530</b> on the remote machine <b>30</b>, which hooks one or more window creation application programming interfaces (APIs), such as for example, a create window type of API in a WINDOWS based environment. In some embodiments, the window processing mechanism <b>1550</b> intercepts all messages <b>1540</b> to windows <b>1535</b> of the application <b>1530</b>. In other embodiments, the window processing mechanism <b>1550</b> intercepts messages <b>1540</b> of a certain message identifier or name. In one embodiment, the message <b>240</b> may have arguments, parameters or values that are used by the window processing mechanism <b>1550</b> to determine that the message <b>1540</b> should be intercepted. In additional embodiments, the window processing mechanism <b>1550</b> intercepts messages <b>1540</b> to some of the windows <b>1535</b> of the application <b>1530</b>, and in further embodiments, only for a portion of the types of messages <b>240</b> communicated to these windows <b>1535</b>. In yet another embodiment, the window processing mechanism <b>1550</b> is configurable, for example, by a user, to select the messages <b>1540</b>, by name, type, or otherwise, to be intercepted.

0574In some embodiments, the window processing mechanism <b>1550</b> intercepts messages <b>1540</b> communicated to or intended for a top-level window <b>1535</b> of the application <b>1530</b>. In other embodiments, the window processing mechanism <b>1550</b> may intercept any level of window <b>1535</b>, or only certain levels of windows <b>1535</b> in a hierarchy of windows <b>1535</b>. For example, the window processing mechanism <b>1550</b> may ignore any popup dialog windows of a second level window displayed on top of or in front of a top-level window <b>1535</b>.

0575In one embodiment, the window processing mechanism <b>1550</b> may intercept a message <b>1540</b> but pass the message <b>1540</b> through or communicate the message <b>1540</b> to the original or replaced window procedure. In some embodiments, the window processing mechanism <b>1550</b> ignores certain messages <b>1540</b>. In another embodiment, the window procedure of the window processing mechanism <b>1550</b> also includes the functionality and operations of the replaced window procedure. As such, the window processing mechanism <b>1550</b> may intercept a message <b>1540</b> and have either the replaced window procedure or the window procedure hooked into the application <b>1540</b> process the message <b>1540</b>.

0576At step <b>1630</b>, the window processing mechanism <b>1550</b> modifies the message <b>1540</b> to provide the window <b>1535</b> on the client machine <b>10</b> based on the desired display layout <b>1520</b> for the client machine <b>10</b>. In some embodiments, the window processing mechanism <b>1550</b> examines, inspects, analyzes, or otherwise processes any values, arguments, or parameters of the message <b>1540</b> in comparison to the display layout <b>1520</b> for the client machine <b>10</b> displaying the application <b>1530</b>. Based on the comparison, the window processing mechanism <b>1550</b> may modify, adjust, edit, change, alter, replace, translate or otherwise set or provide values, arguments, and/or parameters for the message <b>1540</b> that will provide the desired behavior, appearance and attributes of the window <b>235</b> as displayed or to be displayed by the application <b>1530</b> on the client machine <b>10</b> in accordance with the display layout <b>1520</b>. For example, the values and/or parameters of the message <b>1540</b> may indicate a size, position, location, resolution or other attributes of the window <b>1535</b>. These characteristics may be based on a display environment different than as specified in the display layout <b>1520</b>. As such, in some embodiments, the window processing mechanism <b>1550</b> may modify the size, position, location, resolution or other attributes of the message <b>1540</b> for a display <b>1522</b><i>a</i>-<b>1522</b><i>n </i>specified in the display layout <b>1520</b>.

0577By way of further example, and referring now to <figref idref="DRAWINGS">FIG. 16B</figref>, the window processing mechanism <b>1550</b> may intercept and modify a message <b>1540</b> identified as one of the following: 1) WM_GETMAXMININFO, 2) WM_WINDOWPOSCHANGING, 3) WM_WINDOWPOSCHANGED, and 4) WM_DISPLAYCHANGE. At illustrative step <b>1630</b><i>a</i>, for a message <b>1540</b> intercepted and identified as a WM_GETMINMAXINFO, the window processing mechanism <b>1550</b> analyzes the position of the application <b>1530</b>, i.e., a top-level window <b>1535</b>, relative to the one or more displays <b>1522</b><i>a</i>-<b>1522</b><i>n </i>of the display layout <b>1520</b>, and determines which of the displays <b>1522</b><i>a</i>-<b>1522</b><i>n </i>the application <b>1530</b> should be maximized to. The window processing mechanism <b>1550</b> modifies the message <b>1540</b> to provide values corresponding and translated to the resolution based on the desired display layout <b>1520</b>. For example, a remote machine <b>30</b> may provide window resolution for a single monitor session, and the window processing mechanism <b>1550</b> translates the resolution to the multiple display environment provided via the display layout <b>1520</b>. As such, this technique enables the application <b>1530</b> to maximize to a desired location in accordance with the display layout <b>1520</b>, instead of the single monitor session.

0578At illustrative step <b>1630</b><i>b</i>, for a message <b>1540</b> intercepted and identified as WM_WINDOWPOSCHANGING, the window processing mechanism <b>1550</b> determines if the window <b>1535</b> is in the maximized state, and if so, the message <b>1540</b> is modified to set the window flag to a no move style of window, or otherwise to fix the location or position of the window <b>1535</b>, or not allow the position of the window <b>1535</b> to change. As such, in the maximized state a user may not be able to move the window <b>1535</b>. This technique enables the application <b>1530</b>, or a window <b>1535</b> of the application <b>1530</b> to be maximized to a set or fixed location on a display <b>1522</b><i>a</i>-<b>1522</b><i>n </i>specified by the display layout <b>1520</b>. In some embodiments, either in response to the WM_WINDOWPOSCHANGING message <b>1540</b> or otherwise, the window processing mechanism <b>1550</b> determines the window <b>1535</b> is not in the maximized state, and modifies the message <b>1540</b> to remove the no move style, e.g., the window's position is no longer fixed, or to otherwise allow the position of the window <b>1535</b> to be moved.

0579At illustrative step <b>1630</b><i>c</i>, for a message <b>1540</b> intercepted and identified as WM_WINDOWPOSCHANGED, the window processing mechanism <b>1550</b> compares the position or location of the window <b>1535</b> to the display layout <b>1520</b> and if the window <b>1535</b> is to be rendered outside the screen or work area of display <b>1522</b><i>a</i>-<b>1522</b><i>n</i>, then the position or location of the window <b>1535</b> is changed to be rendered in at least a portion of the screen or work area of the display <b>1522</b><i>a</i>-<b>1522</b><i>n</i>. This technique enables the user not to lose the application <b>1530</b> or window <b>1535</b> of the application <b>1530</b> to an off-screen location.

0580At illustrative step <b>1630</b><i>d</i>, for a message <b>1540</b> intercepted and identified as WM_DISPLAYCHANGED, the window processing mechanism <b>1550</b> suspends passing of messages <b>1540</b> until a new or second display layout <b>1520</b> is obtained or provided for the client <b>1505</b>. In one embodiment, the window processing mechanism <b>1550</b> suspends the processing of all messages <b>1540</b>. In some embodiments, the window processing mechanism <b>1550</b> suspends messages <b>1540</b> that are intercepted and communicated to the replaced or original window procedure. In other embodiments, the window processing mechanism <b>1550</b> suspends messages for the replaced or original window procedure while continuing to process other messages <b>1540</b>. This technique enables a client machine <b>10</b> to dynamically change the display layout <b>1520</b> at any time, for example, during the execution of an application <b>1530</b>.

0581Although the techniques of are generally described above in relation to message, one ordinarily skilled in the art will recognize and appreciate that any message of any type and/or form may be used. Furthermore, the window processing mechanism <b>1550</b> may perform any logic, function, operations or rules based on the message <b>1540</b> and/or the display layout <b>1520</b>, and even for the same type of message <b>1540</b>, may perform a different operation or function for each instance of the message <b>1540</b> depending on changes to the display layout <b>1520</b> or any events, conditions or status of the environment <b>1500</b>, <b>1501</b> or <b>1502</b>.

0582Referring back to <figref idref="DRAWINGS">FIG. 16A</figref>, at step <b>1635</b> of method <b>300</b>, the window <b>1535</b> is displayed on the client machine <b>10</b> based on the message <b>1540</b> processed via the window processing mechanism <b>1550</b>. As such, when the window processing mechanism <b>1550</b> modifies the message <b>1540</b> based on the display layout <b>1520</b>, the window <b>1535</b> is displayed on the client machine <b>10</b> according to the display layout <b>1520</b>. In some embodiments, the window processing mechanism <b>250</b> does not modify the message <b>1540</b>, and therefore, the window <b>1540</b> is displayed on the client machine <b>10</b> according to the unmodified message <b>1540</b>. The technique as illustrated above enables, for example, in one embodiment of a server-based computing environment <b>1500</b>, an application <b>1530</b> running on remote machine <b>30</b> to provide display output to the client machine <b>10</b> that controls and directs the behavior, appearance, and attributes of windows in the display output in any manner desired and specified by the display layout <b>1520</b>, which may not correspond to the physical display layout of the client machine <b>10</b>.

0583In another aspect, although techniques described herein are generally described with a window management system from WINDOWS operating system, one ordinarily skilled in the art will recognize and appreciate that techniques described herein may be practiced with any type and/or form of window manager or management system, such any type and/or form of X-windows managers, including any custom or open-source based window manager running on any type of operating system.

0584Referring now to <figref idref="DRAWINGS">FIG. 16C</figref>, these techniques may be practiced during the re-connection, re-establishment or re-authentication of any communication session or user session, for example a remote display session between the client machine <b>10</b> and the remote machine <b>30</b>. In one embodiment, the session login mechanism <b>1545</b> as illustrated on the remote machine <b>30</b> of <figref idref="DRAWINGS">FIGS. 15A and 15B</figref> may include the window processing mechanism <b>1550</b>, or any portion thereof. In brief overview of method <b>350</b>, the session login mechanism <b>1545</b>, at step <b>1652</b>, accesses or obtains the display layout <b>1520</b> from the storage element <b>1525</b>. At step <b>1654</b>, there may be a disconnection and reconnection processed by the session login mechanism <b>1545</b>. Upon re-establishing and/or re-authenticating the session, the session login mechanism, at step <b>1656</b>, compares a location of a window <b>1535</b> to the client's display layout <b>1520</b>, and at step <b>1658</b>, modifies the window <b>235</b> to display on the client machine <b>10</b> based on the client's display layout <b>1520</b>.

0585At illustrative step <b>1652</b>, the session login mechanism <b>1545</b> obtains information on the display layout <b>1520</b> by any suitable means and/or mechanisms. For example, the window processing mechanism <b>1550</b> included in or used by the session login mechanism <b>1545</b> may have executable instructions, such as file I/O operations, to access a globally mapped data file <b>1525</b>. In another embodiment, the session login mechanism <b>1545</b> may load dynamically linked libraries that load, read or otherwise access the storage element <b>225</b> having the display layout information. In one embodiment, as part of establishing or re-establishing the session, the session login mechanism <b>1545</b> may obtain the display layout <b>1520</b> from the client <b>1520</b>. For example, the session login mechanism <b>1545</b> requests the display layout <b>1520</b> from the client machine <b>10</b> along with any identification or authentication credentials.

0586At illustrative step <b>1654</b>, any type of disconnection or disruption to a session between the client machine <b>10</b> and remote machine <b>30</b> may occur, and any type of reconnection or re-establishment of the session may be facilitated via the session login mechanism <b>1545</b>. In some cases, a user may cause a disconnection or disruption, temporary or otherwise, to a session between the client machine <b>10</b> and the remote machine <b>30</b> due to physical changes in the client's display environment or because the user moves to another client machine <b>10</b>. In one case, the user moves from a first client machine <b>10</b><i>a</i>, such as a work computer, to a second client machine <b>10</b><i>b</i>, such as a home computer. The remote machine <b>30</b> may maintain the same user session between computing devices <b>100</b><i>a</i>-<b>110</b><i>b </i>but the display layout <b>1520</b> may have changed. In another case, the user and/or the client machine <b>10</b> may traverse network segments or network access points that cause changes in the network address or host name, e.g., internet protocol (IP) address, of the client machine <b>10</b> or causes the client machine <b>10</b> to disconnect. The client machine <b>10</b> may reconnect, manually or automatically, to the network <b>1504</b>, such as via the client agent <b>1508</b>. As such, the session login mechanism <b>1545</b> may facilitate or be used to facilitate the reconnection.

0587At step <b>1656</b> of method <b>350</b>, the session login mechanism <b>1545</b> compares the location or position of a window <b>1535</b> of an application <b>1530</b> in relation to the desired display layout <b>1520</b>. In some embodiments, the session login mechanism <b>1545</b> intercepts a message <b>1540</b> to a window <b>1535</b>, and examines, inspects or analyzes any portion of the message <b>1540</b>, such as a value or parameter. In one embodiment, the session login mechanism <b>1545</b> queries, acquires or obtains the current location or position of one or more windows <b>1535</b> of the application <b>1530</b> via an application programming interface (API). In another embodiment, the session login mechanism <b>1545</b> requests from the application <b>1530</b>, the location or position of any of the application's windows. The session login mechanism <b>1545</b> compares the location, position, size, and any other attributes of the window <b>1535</b> to any information in the display layout <b>1520</b>.

0588At step <b>1658</b>, the session login mechanism <b>1545</b> may modify the window <b>1535</b> based on the desired display layout <b>1520</b>. From the comparison of the information about the window <b>1535</b> to the information of the display layout <b>1520</b>, the session login mechanism <b>1545</b>, in some embodiments, modifies the window <b>1535</b> to display on the client machine <b>10</b> via a display <b>1522</b><i>a</i>-<b>1522</b><i>n </i>identified in the display layout <b>1520</b> in a desired manner. In one embodiment, via the functionality of the window processing mechanism <b>1550</b> embodied in or interfaced with the session login mechanism <b>1545</b>, a message <b>1540</b> to a window <b>1535</b> may be intercepted and modified in accordance with the operations described herein. In another embodiment, the session login mechanism <b>1545</b> may modify one or more windows <b>1535</b> of the application <b>1530</b> via any application programming interface (API) to modify such windows <b>1535</b>. The techniques depicted by method <b>350</b> enable client sessions to be disconnected and reconnected and have the display of windows be adjusted accordingly to any new or changed display environments of the client machine <b>10</b>, new or changed display layouts <b>1520</b> of the client machine <b>10</b>, or changes from one client machine <b>10</b><i>a </i>to another client machine <b>10</b><i>b. </i>

0589In another aspect, dynamically changing a display layout <b>1520</b> for a client machine <b>10</b> is described. Referring now to <figref idref="DRAWINGS">FIG. 16D</figref>, the techniques described may be practiced for a change to a display layout <b>1520</b> that occurs during the execution of an application <b>1530</b>. In brief overview of illustrative method <b>360</b>, at step <b>1662</b>, a client's display layout <b>1520</b> is changed. At step <b>1664</b>, the window processing mechanism <b>350</b> suspends window message processing when the client's display layout <b>1520</b> is changed. At step <b>1666</b>, an updated or a second display layout <b>1520</b>′ is obtained by the window processing mechanism <b>1550</b>, and at step <b>1668</b>, the window processing mechanism <b>1550</b> resumes intercepting and modifying messages <b>1540</b> to windows <b>1535</b> based on the second display layout <b>1520</b>′.

0590In further detail, at step <b>1662</b>, the display layout <b>1520</b> may be changed at any time and for any reason. In one embodiment, the display environment for the client machine <b>10</b> may change and the display layout <b>1520</b> may be updated to reflect the changed display environment. For example, another display device <b>124</b> may be connected to the client machine <b>10</b>. In another embodiment, a user of the client machine <b>10</b> may be making adjustments, updating or otherwise changing the display layout <b>1520</b> to suit the user's desire for a behavior and appearance of applications <b>1530</b> and the display of windows <b>1535</b> of the application <b>1530</b> on the client machine <b>10</b>. In yet a further embodiment, a first session may be on a first client machine <b>10</b> with a first display layout <b>1520</b>, and the user switches to a second session or maintains the first session on a second client machine <b>10</b>′ with a second or updated display layout <b>1520</b>′.

0591At step <b>1665</b>, the method suspends intercepting and modifying messages <b>1540</b> for windows <b>1535</b> of an application <b>1530</b> upon notification of a change to the display layout <b>1520</b>. In one embodiment, the window processing mechanism <b>1550</b> intercepts a message <b>1540</b>, such as the WM_DISPLAYCHANGE message, indicating a change in any attribute or characteristic, for example, the resolution, of the display environment. In another embodiment, the client machine <b>10</b> communicates a notice to the remote machine <b>30</b>, the window processing mechanism <b>1550</b> or the session login mechanism <b>1545</b> indicating a change has occurred or is about to occur to the display layout <b>1520</b>. In yet another embodiment, the application <b>1530</b> may comprise a user interface mechanism for a user to indicate a change to the display environment, or to have the application <b>1530</b> suspend processing of window messages according to the display layout <b>1520</b>.

0592The window processing mechanism <b>1550</b> may suspend the processing of messages <b>240</b> for all applications <b>230</b>, a portion of applications <b>230</b>, or for a portion of windows <b>235</b> of one, some, or all of the application <b>230</b>. In one embodiment, the window processing mechanism <b>1550</b> queues any messages <b>240</b> received until the window processing mechanism <b>1550</b> obtains another display layout <b>1520</b>. In another embodiment, the window processing mechanism <b>1550</b> only suspends processing of window messages to be modified according to the display layout <b>1520</b>, and continues passing the messages <b>240</b> not to be modified to the original or replaced window procedure.

0593At step <b>1666</b> of the method, an updated or a second display layout <b>1520</b>′ is obtained to use for window message processing. The updated or second display layout <b>1520</b>′ may be provided by any suitable means and/or mechanisms. In one embodiment, the updated or second display layout <b>1520</b>′ is stored with the first display layout <b>1520</b> in the storage element <b>225</b>. In another embodiment, the updated or second display layout <b>1520</b>′ is stored as an updated version of the first display layout <b>1520</b>, and in further embodiments, the second display layout <b>1520</b>′ may replace the first display layout <b>1520</b> in the storage element <b>225</b>. In one embodiment, the client machine <b>10</b> communicates the updated or second display layout <b>1520</b>′ to the remote machine <b>30</b> or stores the second display layout <b>1520</b>′ to the storage element <b>225</b> on the remote machine <b>30</b>. In some embodiments, the client machine <b>10</b> via a reconnection or re-establishment to the remote machine <b>30</b> may provide an updated display layout <b>1520</b>. In one embodiment, the client machine <b>10</b> communicates an unchanged display layout <b>1520</b> or a display layout <b>1520</b> to the remote machine <b>30</b> that the remote machine <b>30</b> already has stored in the storage element <b>225</b>. In yet other embodiments, the remote machine <b>30</b> or client machine <b>10</b> may obtain the second display layout <b>1520</b>′ from another client machine <b>10</b> on the network <b>204</b>, such as downloading the second display layout <b>1520</b>′ form a remote machine <b>30</b>. As described above in connection with illustrative method <b>300</b>, the window processing mechanism <b>350</b> may obtain the display layout <b>1520</b> from the storage element <b>225</b> by a variety of means and/or mechanisms.

0594At step <b>1668</b> of method <b>360</b>, the window processing mechanism <b>1550</b> resumes intercepting and modifying messages <b>240</b> to windows <b>235</b> based on the second display layout <b>1520</b>. In one embodiment, if the window processing mechanism <b>1550</b> queued any messages <b>240</b>, the window processing mechanism <b>1550</b> analyzes and modifies the queued messages <b>240</b> based on the second display layout <b>1520</b>′. Otherwise, the window processing mechanism <b>1550</b> uses the second display layout <b>1520</b>′ to modify any messages <b>240</b> intercepted after obtaining the second display layout <b>1520</b>′. Using the techniques described herein, a client display environment and a client's display layout can be dynamically changed during the course of executing one or more applications, and the display of windows for the application appear and behave according to the changes to the display layout. For example, another display device may be added to the client, and an application may be minimized during a change in the display layout. When the display layout is updated, the user can maximize the application and have the application appear in the appropriate display even though the display environment changed when the application was minimized.

0595In view of the functions, structures, and operations described above, systems and methods are provided to control and direct the appearance, behavior and attributes of windows of an application in a flexible manner for virtualizing, simulating or providing a multiple display environment without restricting or limiting the client side display configuration. For example, the display layout of the client may not be limited to configure the physical monitor of the client as the primary display, i.e. as the top left most monitor in the display layout configuration. The systems and methods described may be practiced in a server-based or thin-client based computing environment, with clients having multiple display devices, or with clients having a single display device. Additionally, the configuration of a display layout that is not restricted or limited to the physical display environment of the client is provided. The display environment of the client may extend to include additional virtual displays, so if the client has two display devices, three or more displays may be virtualized or simulated for the client. A single display configuration for a single display device may be implemented while still changing the appearance and behavior of windows based on a desired or customized display layout. A client or user may gain the functionality, benefits, and advantages of a multiple display environment without having multiple display devices, or having all the display devices desired.

0596In one embodiment, multi-monitor support provides maximizing of windows to fill a single monitor rather than the full screen and centering of dialogs on a monitor rather than on a screen. In another embodiment the session management component, the virtual machine service component, and a multi-monitor hook component executing in a computing environment provided by a virtual machine together provide multi-monitor support in a virtual machine environment. In still another embodiment, a multi-monitor hook component and a component acquiring client geometry data provide multi-monitor support in a virtual machine environment.

0597In one embodiment, the session management component <b>1300</b> reads the monitor configuration for the client machine <b>10</b> from a multi-monitor hook file mapping. In some embodiments where a user of the client machine <b>10</b> establishes a connection to a presentation server executing on an execution machine in which the virtual machine provides access to a computing environment, the presentation server generates the multi-monitor hook file mapping upon establishment of the connection by the user.

0598In one embodiment, the session management component <b>1300</b> sends a message to the virtual machine service component containing the monitor layout for the user. In some embodiments, the message is sent when the session management component <b>1300</b> detects a user reconnection, so that the monitor layout remains synchronized with the client machine <b>10</b>.

0599The virtual machine service component receives the monitor layout messages provided by the session management component <b>900</b>. In some embodiments, the virtual machine service component creates a file mapping in the computing environment and updates the file to include monitor layout data.

0600In other embodiments, the virtual machine service component also creates a checksum for the data that is used by the multi-monitor hook component to ensure that it has correctly read the layout data. In one of these embodiments, a checksum is used rather than a locking scheme to synchronize access to the layout data. In this embodiment, the checksum does not cause any blocking between the processes reading the data. The layout data is updated infrequently and may be small in size, so the checksum calculation may complete quickly. In another of these embodiments, the reader processes save the checksum, read the data and recalculate the checksum. If the calculated checksum does not match the saved checksum it indicates that the data was updated while it was being read and the process is repeated. As the data is usually only updated when the user reconnects to another client and given the short time required to read the data, it is unlikely that a reader would have to reread the data more than once for a particular change. In some embodiments, the virtual machine service component uses a stored default display setting for the client machine <b>10</b>, the stored default selected to ensure that the computing environment has valid display settings upon initialization of the session.

0601In some environments, a multi-monitor hook component executes in a computing environment provided by a virtual machine. In one of these embodiments, the multi-monitor hook component receives an event for each window created just before the window is created, including a window handle for the window being created. The multi-monitor hook component may identify a window type of the window and determine to hook window messages for the window. In some embodiments, windows having window types indicating that the window can be maximized or that the window is a dialog will be hooked. Hooked windows may be added to an array that contains the window handle and an original window procedure. In other embodiments, the multi-monitor hook component receives an event indicating that a window is about to be destroyed. In one of these embodiments, the multi-monitor hook component removes the entry in the hook array associated with the window.

0602In some embodiments, the multi-monitor hook component receives an identification of a window after the window is created and before the window is displayed. In one of these embodiments, the multi-monitor hook component checks the position of the dialog and if it spans multiple monitors, the multi-monitor hook component repositions the window to the centre of the monitor that contains most of the dialog, or the first monitor containing the dialog if the dialogs area is equally split between two monitors. In other embodiments, the multi-monitor hook component receives an event when a window is about to be maximized. The multi-monitor hook component ensures that when the window is maximized from the minimized state it will be positioned on the correct monitor.

0603In some embodiments, the multi-monitor hook component receives an event when a window is being maximized. The multi-monitor hook component checks the state of the window and, if the window is minimized, the multi-monitor hook component retrieves an identification of a monitor in which the window is minimized from the window hook array. If the window is not minimized, the multi-monitor hook component identifies the monitor that contains most of the window. If no monitor is found, or if the monitor does not exist (as after a reconnection) monitor <b>0</b> is used. The multi-monitor hook component then removes the origin and size of the monitor from its saved monitor information and updates the MINMAXINFO structure pointed to by the message. This causes the window to maximize to the specified monitor only.

0604In some embodiments, the virtual machine service component receives authentication information associated with a user of the client machine <b>10</b>. In one of these embodiments, the virtual machine service component receives the authentication information from a protocol stack component receiving the credentials from the client machine <b>10</b>. In another of these embodiments, the virtual machine service component receives authentication information from the session management component <b>1300</b>. In still another of these embodiments, the virtual machine service component uses the received authentication information to authenticate the user of the client machine <b>10</b> to the computing environment provided by the virtual machine.

0605In one embodiment, when the communications channel is established and the initial session related information is passed to the virtual machine service component, the virtual machine service component automatically logs the user into the computing environment. In one embodiment, the virtual machine service component receives credentials from the session management component <b>1300</b>. In another embodiment, the virtual machine service component receives credentials previously provided by the user. In some embodiments, the user provides credentials to the client machine <b>10</b> prior to requesting access to a resource. In one of these embodiments, the user provides credentials to a client agent, such as an ICA client. The virtual machine service component automatically reconfigures the display settings of the guest operating system to match those of the ICA client. The virtual machine produces graphics and sound output to the virtual devices that redirect that output to a client agent, such as an ICA client, on the requesting machine. The virtual machine receives audio input, mouse and keyboard device data redirected from the ICA client. When the virtual machine is shutdown or suspended the session management component <b>1300</b> cleans up and shuts down the ICA session.

0606The remote machines <b>30</b>, <b>30</b>′, and <b>30</b>″ can belong to the same authentication domain. A domain may comprise a group of machines, such as application servers, execution machines, or client nodes under control of one security database. A domain can include one or more machine farms linked together to act as a single system to provide centralized administration. Conversely, a machine farm can include one or more domains. For servers of two different domains to belong to the same machine farm, a trust relationship may need to exist between the domains. A trust relationship is an association between the different domains that allows a user to access the resources associated with each domain with just one log-on authentication.

0607In one embodiment, the remote machine <b>30</b>′″ is in a different domain than the farm <b>38</b>. In another embodiment, the remote machine <b>30</b>′″ is in the same domain as machines <b>30</b>, <b>30</b>′, and <b>30</b>″. For either embodiment, machines <b>30</b>, <b>30</b>′, and <b>30</b>″ can belong to one server farm, while the remote machine <b>30</b>′″ belongs to another machine farm, or all of the machines <b>30</b>, <b>30</b>′, <b>30</b>″ and <b>30</b>′″ can belong to the same machine farm. When a new machine is connected to the network <b>150</b>, the new machine either joins an existing machine farm or starts a new machine farm.

0608The machines <b>10</b> may be in a domain, or may be unconnected with any domain. In one embodiment, the client machine <b>10</b> is in the domain <b>38</b>. In another embodiment, the client machine <b>10</b> is in another domain that does not include any of the machines <b>30</b>, <b>30</b>′, <b>30</b>″ and <b>30</b>′″. In another embodiment, the client machine <b>10</b> is not in any domain.

0609In one embodiment the client machine <b>10</b> is in the domain <b>38</b> and a user of the machine provides user credentials to log onto the client machine <b>10</b>. User credentials typically include the name of the user of the machine, the password of the user, and the name of the domain in which the user is recognized. The user credentials can be obtained from smart cards, time-based tokens, social security numbers, user passwords, personal identification (PIN) numbers, digital certificates based on symmetric key or elliptic curve cryptography, biometric characteristics of the user, or any other means by which the identification of the user of the client node can be obtained and submitted for authentication.

0610From the user-provided credentials, the client machine <b>10</b> generates user authentication data. The client machine <b>10</b> transmits this user authentication data to the remote machine <b>30</b>. In this embodiment, the user credentials are not transmitted over a network, only the resulting user authentication data is transmitted by the client machine <b>10</b>.

0611The remote machine <b>30</b> may determine which resources hosted by the machine farm containing remote machine <b>30</b> are available for use by the user of the client machine <b>10</b>. In one embodiment, the remote machine <b>30</b> consults user authentication data to make this determination. In another embodiment, the remote machine <b>30</b> consults information associated with a resource requested by the user to make the determination. The remote machine <b>30</b> transmits information representing the available resources to the client machine <b>10</b>.

0612The user authentication performed by the remote machine <b>30</b> can suffice to authorize the use of each hosted resource presented to the client machine <b>10</b>, although such resources may reside at another machine. Accordingly, in this embodiment, when the client machine <b>10</b> accesses or launches (i.e., initiates execution of) one of the hosted resources, additional input of user credentials by the user will be unnecessary to authenticate access to that resource. Thus, a single entry of the user credentials can serve to determine the available resources and to authorize the access or launching of such resources without an additional, manual log-on authentication process by the user.

0613<figref idref="DRAWINGS">FIG. 17</figref> depicts in more detail a system for remotely authenticating a client of a client machine <b>10</b> to a remote machine <b>30</b>. As shown in <figref idref="DRAWINGS">FIG. 17</figref>, the client machine <b>10</b> includes an authentication module <b>1710</b> in communication with a thin-client program <b>1720</b>. The authentication module <b>1710</b> receives user authentication credentials provided for the purposes of authenticating a user to the client machine <b>100</b>, the remote machine <b>30</b>, or both. Received authentication credentials can include username-password combinations, graphical password data, data derived from time-based tokens such as the SecurID line of tokens manufactured by RSA Security Inc. of Bedford, Mass., challenge-response data, information from smart cards, and biometric information such as fingerprints, voiceprints, or facial features. The authentication module <b>1710</b> may use the provided authentication credentials to authenticate the user to the machine <b>100</b>. For example, in WINDOWS-based environments, the authentication module <b>1710</b> may be provided by the MSGINA dynamically-linked library. In other embodiments, for example, in Unix-based environments, the authentication module <b>1710</b> may be provided by the Unix Pluggable Authentication Manager, using the pam_krb module. In still other embodiments, the authentication module <b>1710</b> may be provided by the UNIX kinit command program.

0614In the embodiment shown in <figref idref="DRAWINGS">FIG. 17</figref>, the machine <b>100</b> also includes a security service <b>1712</b>. In some embodiments, the authentication module <b>1710</b> and the security service <b>1712</b> are provided as the same dynamically-linked library. The security service <b>1712</b> provides security services to modules and applications on the machine <b>100</b>, including the authentication module <b>1710</b> and the thin-client application <b>1720</b>, such as authentication to the machine <b>100</b> and authentication to remote machines or network services. For example, the security service <b>1712</b>, which may be the GSSAPI specified by the Internet Engineering Task Force (IETF) or the SSPI manufactured by Microsoft Corporation of Redmond, Wash., may obtain a Kerberos ticket in response to receipt of the user authentication credentials and use this ticket to obtain additional Kerberos tickets to authenticate the user to remote machines or network services, at the request of modules or applications on the machine <b>100</b>. The security service <b>1712</b> may then generate user authentication data using these Kerberos tickets if needed for remote authentication. In one embodiment, the security service <b>1712</b> may generate the user authentication data using an external authentication service, such as a Key Distribution Center in a Kerberos environment or Active Directory in a Windows-based environment.

0615The security service <b>1712</b> provides the generated user authentication data, e.g., Kerberos ticket and associated Kerberos authenticator, to the thin-client application <b>1720</b>. The thin-client application <b>1720</b> transmits the user authentication data to a remote machine <b>30</b> for remote authentication of the user. Thus, unlike existing single sign-on mechanisms for server-based computing, user-provided authentication credentials are not transmitted over the network <b>150</b> to a remote machine <b>30</b>. The user authentication data generated by the security service <b>1712</b> is independent of the method used by the user to authenticate to the machine <b>100</b>. Thus, for example, a Kerberos ticket for the user of machine <b>100</b> is obtained whether the user uses a username-password combination or a biometric to authenticate to the machine <b>100</b>.

0616In the embodiment shown in <figref idref="DRAWINGS">FIG. 17</figref>, the thin-client application <b>1720</b> communicates with the remote machine <b>30</b> via a thin-client protocol having one or more virtual channels <b>1735</b>. In these embodiments, the thin-client application <b>1720</b> loads a virtual channel driver and uses it to send and receive messages on the authentication virtual channel. In some embodiments, the virtual channel driver exposes functions for opening the virtual channel and sending data over it.

0617The thin-client application <b>1720</b> passes a data structure to the remote machine <b>30</b> for the virtual channel <b>1735</b> when the thin-client protocol connection is established, indicating to the server-side thin-client application <b>1750</b> that the authentication virtual channel is available. In one embodiment, the virtual channel data structure for the authentication virtual channel contains the virtual channel information and a representation of the size of the largest data packet the machine <b>100</b> can accept from or send to the remote machine <b>30</b> over the virtual channel <b>1735</b>. The data packet size is constrained by the maximum thin-client size and any specific memory restrictions imposed by the client machine <b>10</b>. In one particular embodiment, the data structure for the authentication virtual channel is defined as:

0000<tables id="TABLE-US-00003" num="00003"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="offset" colwidth="63pt" align="left" /><colspec colname="1" colwidth="154pt" align="left" /><thead><row><entry /><entry namest="offset" nameend="1" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>typedef struct _C2H</entry></row><row><entry /><entry>{</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="63pt" align="left" /><colspec colname="1" colwidth="42pt" align="left" /><colspec colname="2" colwidth="112pt" align="left" /><tbody valign="top"><row><entry /><entry> VD_C2H</entry><entry>Header;</entry></row><row><entry /><entry> UINT16</entry><entry>cbMaxDataSize;</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="offset" colwidth="63pt" align="left" /><colspec colname="1" colwidth="154pt" align="left" /><tbody valign="top"><row><entry /><entry>} C2H, *PC2H;</entry></row><row><entry /><entry namest="offset" nameend="1" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0618The server-side thin-client application <b>1750</b> indicates to the thin-client application <b>1720</b> its intention to perform authentication using the authentication virtual channel <b>1735</b> by opening the virtual channel and sending a bind request message onto the channel. Once the virtual channel has been opened, the virtual channel driver in the thin-client application <b>1720</b>, in one embodiment, reads a message requesting a binding from the virtual channel, sends a message onto the virtual channel responding to the bind request; and reads a “commit” message from the channel. In one embodiment, the message requesting a binding includes data specifying the protocol version that is supported. In other embodiments, the protocol version can be negotiated between the thin-client application <b>1720</b> and the server-side thin-client application <b>1750</b> using the bind request and bind response messages.

0619The bind request, bind response, and bind commit initialization messages allow the server-side thin-client application <b>1750</b> and the thin-client application <b>1720</b> to conduct a 3-way handshake initiated by the server-side thin-client application <b>1750</b>, and negotiate capabilities. A 2-way handshake may be initiated by the server-side thin-client application <b>1750</b> when the current set of virtual channel capabilities can be negotiated using a 2-way handshake only, but a 3-way handshake is supported to allow more flexibility that might be required by new capabilities or future enhancements to current capabilities. For example, in a 3-way handshake, after receiving a “menu” of capabilities from the server-side thin-client application <b>1750</b>, the thin-client application <b>1720</b> can exhibit a specific preference or could instead acknowledge a whole set of options pertaining to a specific capability thus letting the server-side thin-client application <b>1750</b> decide on a specific option. In a 2-way handshake to be initiated by the thin-client application <b>1720</b>, the thin-client application <b>1720</b> could not exhibit a specific preference because it might not be supported by the host.

0620Following channel setup, the virtual channel driver of both the thin-client application <b>1720</b> and the server-side thin-client application <b>1750</b> does the following in a loop until a “stop” message or an “error” message is received: retrieve authentication data from the security service <b>1712</b>, <b>1712</b>′, providing as input any authentication data sent by the other party via the virtual channel; and send the retrieved authentication data (if any) onto the virtual channel in a data message. If the retrieval of data from the security service <b>1712</b>, <b>1712</b>′ returned a “STOP” message, then signal stop and close the authentication virtual channel. In some embodiments the virtual channel driver may reset itself on a “stop” signal. If the retrieval of data from the security service <b>1712</b>, <b>1712</b>′ returned a “CONTINUE” message, then continue. If the retrieval of authentication data from the security service <b>1712</b>, <b>1712</b>′ returned an “ERROR”, then signal that an error has occurred and close the authentication virtual channel.

0621As long as “stop” or “error” are not signaled, the virtual channel driver of the thin-client application <b>1720</b> and the server-side thin-client application <b>1750</b> are free to exchange data messages until the security service <b>1712</b>, <b>1712</b>′ stops producing data buffers to be sent. In some embodiments, the number of messages exchanged may be limited by the virtual channel driver, the server-side thin-client application <b>1750</b>, or the virtual channel <b>1735</b>. In other embodiments, the virtual channel driver of the thin-client application <b>1720</b> and the server-side thin-client application <b>1750</b> exchange messages sequentially, that is, two messages are not sent in one direction without a reply to the first being sent in the other. In either embodiment, message exchange can stop after a message has been sent in either direction.

0622In some particular embodiments, the data messages are sent over the virtual channel Least Significant Double Word (LSDW), Least Significant Word (LSW), Least Significant Byte (LSB) first. In other particular embodiments, the data messages are aligned at a byte boundary and fully packed in memory. In these embodiments, data fields will be aligned in memory as written to or read from the virtual channel.

0623Some messages transmitted on the authentication virtual channel span multiple virtual channel packets. To support this, every message must be preceded by a message specifying the length of the next transmitted command. An example of a message that may be used to specify the length of the next command is:

0000<tables id="TABLE-US-00004" num="00004"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="offset" colwidth="49pt" align="left" /><colspec colname="1" colwidth="168pt" align="left" /><thead><row><entry /><entry namest="offset" nameend="1" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>typedef struct _PKT_CMDLEN</entry></row><row><entry /><entry>{</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="49pt" align="left" /><colspec colname="1" colwidth="35pt" align="left" /><colspec colname="2" colwidth="133pt" align="left" /><tbody valign="top"><row><entry /><entry> UINT32</entry><entry>Length;</entry></row><row><entry /><entry> UINT8</entry><entry>Command;</entry></row><row><entry /><entry> UINT8</entry><entry>FlagsBitMask;</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="offset" colwidth="49pt" align="left" /><colspec colname="1" colwidth="168pt" align="left" /><tbody valign="top"><row><entry /><entry>} PKT_CMDLEN, *PPKT_CMDLEN;</entry></row><row><entry /><entry namest="offset" nameend="1" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0624In some of these embodiments, PKT_CMDLEN also contains a command number to indicate what type of message is to follow:

0000<tables id="TABLE-US-00005" num="00005"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="28pt" align="left" /><colspec colname="1" colwidth="112pt" align="left" /><colspec colname="2" colwidth="77pt" align="center" /><thead><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>#define CMD_BIND_REQUEST</entry><entry>0x00</entry></row><row><entry /><entry>#define CMD_BIND_RESPONSE</entry><entry>0x01</entry></row><row><entry /><entry>#define CMD_BIND_COMMIT</entry><entry>0x02</entry></row><row><entry /><entry>#define CMD_SSPI_DATA</entry><entry>0x03</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0625A PKT_CMDLEN packet containing Length=0 indicates that no more data will follow (i.e. a logical channel close).

0626The server-side thin-client application <b>1750</b> passes the authentication data it receives over the authentication virtual channel to its security service <b>1712</b>′. If the server-side security service <b>1712</b>′ is able to verify the data, it generates an access token representing a logon session for the user, allowing the user to authenticate to the remote machine <b>30</b> without resubmitting authentication credentials. An access token is a data object that includes, among other things, a locally unique identifier (LUID) for the logon session. If the server-side security service <b>1712</b>′ is not able to verify the data, the user is prompted to resubmit authentication credentials.

0627In some embodiments, until the server-side security service <b>1712</b>′ authenticates the user, the only virtual channel over which the user may communicate with the remote machine <b>30</b> is the authentication virtual channel. In some of these embodiments, after authentication, new virtual channels are initiated for communication. In other embodiments, only one virtual channel exists and it may only be used for authentication-related communications until the user is authenticated, and it may be used for other communications after the user is authenticated.

0628For embodiments in which the remote machine <b>30</b> operates under control of a MICROSOFT WINDOWS operating system, the access token generated by the server-side security service <b>1712</b>′ is an impersonation token that has only network logon rights. That is, the generated access token is not suitable to use for starting applications to run interactively, as is required in the WINDOWS server-based computing environment. To allow applications to run interactively, a primary access token is needed that has interactive logon rights. In one embodiment, the generated access token is modified to provide the appropriate rights. In another embodiment, a new token is generated for the user.

0629For embodiments in which the server-side computing device <b>140</b> operates under control of a Unix-based operating system, if the server-side security service <b>1712</b>′ verifies the authentication data it receives over the authentication virtual channel from the server-side thin-client application <b>1750</b>, the server-side thin-client application <b>1750</b> will grant the user access to the resources. In these embodiments, the server-side security service <b>1712</b>′ does not generate an access token.

0630In some embodiments, after the remote machine <b>30</b> has authenticated the user, the remote machine <b>30</b> presents an enumeration of resources available to the user. In these embodiments, the remote machine <b>30</b> may create a page describing a display of resources, hosted by a plurality of machines, available to the machine <b>100</b>. The remote machine <b>30</b> may then transmit the created page to the machine <b>100</b> for display and receive from the machine <b>100</b>, a request to access one of the hosted resources.

0631In some of these embodiments, the selected one of the available resources hosted by one of the plurality of machines is then executed without requiring further receipt of user authentication data from the machine <b>100</b>. In some of these embodiments, the remote machine <b>30</b> initiates, in response to successful authentication by the user, a connection from the remote machine <b>30</b> to a second remote machine <b>30</b>′ which is hosting a resource available to the user. In these embodiments, the available resource is executed over the connection. In some embodiments, the connection is a virtual channel.

0632In other embodiments, the first remote machine <b>30</b> is hosting the selected one of the available resources. In some of these embodiments, the remote machine <b>30</b> makes the resource available to the user over the existing connection. In others of these embodiments, the remote machine <b>30</b> makes the resource available to the user over a new connection. In some of those embodiments, the new connection comprises a virtual channel.

0633In some embodiments, a plurality of components are provided for authenticating a user of the client machine <b>10</b> to a virtual machine on a remote machine <b>30</b>. In one of these embodiments, functionality is provided for a Kerberos-based Single Sign-On process between the client machine <b>10</b> and a guest operating system provided by the virtual machine.

0634In some embodiments, a user seeking to access a resource provided by a virtual machine provides authentication credentials multiple times to different entities. In one of these embodiments, the user is authenticated by a client agent on the client machine <b>10</b>, by a remote machine <b>30</b>, and by a computing environment provided by a virtual machine in the remote machine <b>30</b>. In some of these embodiments, single sign-on support would enable authentication of the user to different entities with only one transmission of authentication credentials from the user.

0635Authentication of the user to the client machine and the remote machine <b>30</b> may be accomplished as described above in connection with <figref idref="DRAWINGS">FIG. 17</figref>. In some embodiments, an authentication component, a GINA (Graphical Identification and Authentication) component, an authentication module in the session management component and an authentication module for the virtual machine service component are provided. In one embodiment, a bi-directional virtual channel enables communication between a service management component on the remote machine <b>30</b> and a virtual machine service component executing in the guest operating system. In one embodiment, the remote machine <b>30</b> includes client-side single sign-on functionality and the virtual machine includes server-side single sign-on functionality. In still another embodiment, the service management component implements an authentication module and communicates with an authentication module in the virtual machine service component to authenticate the user.

0636In one embodiment, the session management component creates a Kerberos SSPI channel between itself and the virtual machine service component. When the channel is established the session management component acquires the credentials of the user and initializes a security context using this data. The initialization data returned is sent to the virtual machine service component which accepts the data and starts an exchange of SSPI messages between the two components until the security context is established in the virtual machine service component. This context is then used to log the user on to the virtual machine using a single sign-on GINA component.

0637In some embodiments, the session management component authenticates the user to a host operating system on the remote machine <b>30</b>. In one of these embodiments, the host operating system then authenticates the user to the virtual machine. In other embodiments, the session management component authenticates the user to a hypervisor. In one of these embodiments, the hypervisor then authenticates the user to the virtual machine. In still other embodiments, the session management component authenticates the user to a virtual machine providing management functionality for the virtual machine to which the user seeks access.

0638Referring back to <figref idref="DRAWINGS">FIG. 8</figref>, a remote machine <b>30</b> may determine to provide access to a resource streaming service capable of transmitting a requested resource to the client machine (step <b>816</b>). In some embodiments, the remote machine <b>30</b> determines to implement a resource streaming service to transmit to the client machine <b>10</b> or to a remote machine <b>30</b>′ a requested resource. In other embodiments, the remote machine <b>30</b> determines to use a resource streaming service to stream the resource to a computing environment provided by a virtual machine. In still other embodiments, the resource is a computing environment and the remote machine <b>30</b> determines to use a resource streaming technique to stream the computing environment to a virtual machine. In some embodiments, the plurality of resource files resides on the remote machine <b>30</b>′. In other embodiments, the plurality of resource files resides on a separate file server or remote machine <b>30</b>″. In still other embodiments, the plurality of resource files may be transmitted to a client machine <b>10</b>. In yet other embodiments, a file in the plurality of resource files may be executed prior to transmission of a second file in the plurality of resource files to the client machine <b>10</b>.

0639In some embodiments, the remote machine <b>30</b> retrieves information about the enumerated resource from a remote machine <b>30</b>′. In one of these embodiments, the remote machine <b>30</b> receives an identification of a remote machine <b>30</b>″ hosting a plurality of resource files. In another of these embodiments, the remote machine <b>30</b> receives identification of a location of a plurality of resource files, the identification conforming to a Universal Naming Convention (UNC). In still another of these embodiments, the identification includes a network location and a socket for a resource streaming protocol.

0640In one embodiment, the remote machine <b>30</b> retrieves a file containing information about the enumerated resource. The file may include an identification of a location of a remote machine <b>30</b>′ hosting the enumerated resource. The file may include an identification of a plurality of versions of the enumerated resource. The file may include an enumeration of a plurality of resource files comprising the enumerated resource. The file may include an identification of a compressed file comprising a plurality of resources files comprising the enumerated resource. The file may include an identification of pre-requisites to be satisfied by a machine executing the enumerated resource. The file may include an enumeration of data files associated with the enumerated resource. The file may include an enumeration of scripts to be executed on a machine executing the enumerated resource. The file may include an enumeration of registry data associated with the enumerated resource. The file may include an enumeration of rules for use in an embodiment where the enumerated resource executes within an isolation environment. In one embodiment, the file may be referred to as a “manifest” file. The information that the file may contain is described in further detail below.

0641The stream of data packets may include resource files comprising the enumerated resource. In some embodiments, resource files include data files associated with an resource. In other embodiments, resource files include executable files required for execution of the resource. In still other embodiments, the resource files include metadata including information about the files, such as location, compatibility requirements, configuration data, registry data, identification of execution scripts rules for use in isolation environments, or authorization requirements.

0642In some embodiments, the streamed resource executes prior to the transmission of each resource file in a plurality of resource files comprising the streamed resource. In one of these embodiments, execution of the streamed resource begins upon receipt by a client machine <b>10</b> of one resource file in the plurality of resources. In another of these embodiments, execution of the streamed resource begins upon receipt by a client machine <b>10</b> of an executable resource file in the plurality of resource files. In still another of these embodiments, the client machine <b>10</b> executes a first received resource file in a plurality of resource files and the first received resource file requests access to a second resource file in the plurality of resource files.

0643In one embodiment, the streamed resource executes on the client machine <b>10</b> without permanently residing on the client machine <b>10</b>. In this embodiment, the streamed resource may execute on the client machine <b>10</b> and be removed from the client machine <b>10</b> upon termination of the streamed resource. In another embodiment, the streamed resource executes on the client machine <b>10</b> after a pre-deployed copy of each resource file is stored on the client machine <b>10</b>. In still another embodiment, the streamed resource executes on the client machine <b>10</b> after a copy of each resource file is stored in an isolation environment on the client machine <b>10</b>. In yet another embodiment, the streamed resource executes on the client machine <b>10</b> after a copy of each resource file is stored in a cache on the client machine <b>10</b>.

0644In some embodiments, the remote machine <b>30</b> streams the enumerated resource to the remote machine <b>30</b>, executes the enumerated resource on the remote machine <b>30</b>, and provides to the client machine <b>10</b> resource-output data generated by the execution of the enumerated resource. In other embodiments, a resource is streamed to a virtual machine and resource output data is transmitted to a client machine <b>10</b> using a presentation layer protocol such as X11, VNC, ICA or RDP.

0645In one embodiment, the remote machine <b>30</b> receives a plurality of resource files comprising the enumerated resource. In another embodiment, the remote machine <b>30</b> provides the resource-output data via a presentation level protocol, such as an ICA presentation level protocol or a Remote Desktop Windows presentation level protocol or an X-Windows presentation level protocol.

0646In some embodiments, the remote machine <b>30</b> also provides access information associated with the enumerated resource, the access information generated responsive to the selected method. In one of these embodiments, the access information provides an indication to the client machine <b>10</b> of the selected method for execution of the enumerated resource. In another of these embodiments, the access information includes an identification of a location of the enumerated resource, the identification conforming to a Universal Naming Convention (UNC). In still another of these embodiments, the access information includes an identification of a session management server.

0647In some embodiments, the access information includes a launch ticket comprising authentication information. In one of these embodiments, the client machine <b>10</b> may use the launch ticket to authenticate the access information received from the remote machine <b>30</b>. In another of these embodiments, the client machine <b>10</b> may use the launch ticket to authenticate itself to a second remote machine <b>30</b> hosting the enumerated resource. In still another of these embodiments, the remote machine <b>30</b> includes the launch ticket in the access information responsive to a request from the client machine <b>10</b> for the launch ticket.

0648Referring now to <figref idref="DRAWINGS">FIG. 18</figref>, flow diagram depicts one embodiment of the steps taken to access a plurality of files comprising a resource, such as a computing environment or an application program. A client machine <b>10</b> performs a pre-launch analysis (step <b>1810</b>). In one embodiment, the client machine <b>10</b> performs the pre-launch analysis prior to retrieving and executing a plurality of resource files comprising a resource. In another embodiment, the client machine <b>10</b> performs the pre-launch analysis responsive to a received indication that the pre-launch analysis is a requirement for authorization to access the plurality of resource files comprising a resource.

0649In some embodiments, the client machine <b>10</b> receives, from a remote machine <b>30</b>, access information associated with the plurality of resource files. In one of these embodiments, the access information includes an identification of a location of a remote machine <b>30</b>′ hosting the plurality of resource files. In another of these embodiments, the client machine <b>10</b> receives an identification of a plurality of resources comprising one or more versions of the resource. In still another of these embodiments, the client machine <b>10</b> receives an identification of a plurality of resource files comprising one or more resources. In other embodiments, the client machine <b>10</b> receives an enumeration of resources available to the client machine <b>10</b> for retrieval and execution. In one of these embodiments, the enumeration results from an evaluation of the client machine <b>10</b>. In still other embodiments, the client machine <b>10</b> retrieves at least one characteristic responsive to the retrieved identification of the plurality of resource files comprising a resource.

0650In some embodiments, the access information includes a launch ticket capable of authorizing the client machine <b>10</b> to access the plurality of resource files. In one of these embodiments, the launch ticket is provided to the client machine <b>10</b> responsive to an evaluation of the client machine <b>10</b>. In another of these embodiments, the launch ticket is provided to the client machine <b>10</b> subsequent to a pre-launch analysis of the client machine <b>10</b> by the client machine <b>10</b>.

0651In other embodiments, the client machine <b>10</b> retrieves at least one characteristic required for execution of the plurality of resource files. In one of these embodiments, the access information includes the at least one characteristic. In another of these embodiments, the access information indicates a location of a file for retrieval by the client machine <b>10</b>, the file enumerating the at least one characteristic. In still another of these embodiments, the file enumerating the at least one characteristic further comprises an enumeration of the plurality of resource files and an identification of a remote machine <b>30</b> hosting the plurality of resource files.

0652The client machine <b>10</b> determines the existence of the at least one characteristic on the client machine <b>10</b>. In one embodiment, the client machine <b>10</b> makes this determination as part of the pre-launch analysis. In another embodiment, the client machine <b>10</b> determines whether the client machine <b>10</b> has the at least one characteristic.

0653In one embodiment, determining the existence of the at least one characteristic on the client machine <b>10</b> includes determining whether a device driver is installed on the client machine <b>10</b>. In another embodiment, determining the existence of the at least one characteristic on the client machine <b>10</b> includes determining whether an operating system is installed on the client machine <b>10</b>. In still another embodiment, determining the existence of the at least one characteristic on the client machine <b>10</b> includes determining whether a particular operating system is installed on the client machine <b>10</b>. In yet another embodiment, determining the existence of the at least one characteristic on the client machine <b>10</b> includes determining whether a particular revision level of an operating system is installed on the client machine <b>10</b>. For embodiments in which a remote machine <b>30</b> acts as a client machine <b>10</b> (such as, for example, a terminal services session in which the remote machine executes computing resources on behalf of a user of a client machine), determining the existence of at least on characteristic may include determining whether the remote machine <b>30</b> executes a hypervisor or, alternatively, whether the remote machine executes a hypervisor which itself executes in the native operating system.

0654In some embodiments, determining the existence of the at least one characteristic on the client machine <b>10</b> includes determining whether the client machine <b>10</b> has acquired authorization to execute an enumerated resource. In one of these embodiments, a determination is made by the client machine <b>10</b> as to whether the client machine <b>10</b> has received a license to execute the enumerated resource. In another of these embodiments, a determination is made by the client machine <b>10</b> as to whether the client machine <b>10</b> has received a license to receive across a resource streaming session a plurality of resource files comprising the enumerated resource. In other embodiments, determining the existence of the at least one characteristic on the client machine <b>10</b> includes determining whether the client machine <b>10</b> has sufficient bandwidth available to retrieve and execute an enumerated resource.

0655In some embodiments, determining the existence of the at least one characteristic on the client machine <b>10</b> includes execution of a script on the client machine <b>10</b>. In other embodiments, determining the existence of the at least one characteristic on the client machine <b>10</b> includes installation of software on the client machine <b>10</b>. In still other embodiments, determining the existence of the at least one characteristic on the client machine <b>10</b> includes modification of a registry on the client machine <b>10</b>. In yet other embodiments, determining the existence of the at least one characteristic on the client machine <b>10</b> includes transmission of a collection agent <b>704</b> to the client machine <b>10</b> for execution on the client machine <b>10</b> to gather credentials associated with the client machine <b>10</b>.

0656The client machine <b>10</b> requests, from a remote machine <b>30</b>, authorization for execution of the plurality of resource files, the request including a launch ticket (step <b>1812</b>). In some embodiments, the client machine <b>10</b> makes the request responsive to a determination that at least one characteristic exists on the client machine <b>10</b>. In one of these embodiments, the client machine <b>10</b> determines that a plurality of characteristics exist on the client machine <b>10</b>, the plurality of characteristics associated with an enumerated resource and received responsive to a request to execute the enumerated resource. In another of these embodiments, whether the client machine <b>10</b> receives an indication that authorization for execution of the enumerated resource files depends upon existence of the at least one characteristic on the client machine <b>10</b>. In one embodiment, the client machine <b>10</b> received an enumeration of resources, requested execution of an enumerated resource, and received access information including the at least one characteristic and a launch ticket authorizing the execution of the enumerated resource upon the determination of the existence of the at least one characteristic on the client machine <b>10</b>. In one embodiment, the client machine <b>10</b> receives from the remote machine <b>30</b> a license authorizing execution of the plurality of resource files. In some embodiments, the license authorizes execution for a specified time period. In one of these embodiments, the license requires transmission of a heart beat message to maintain authorization for execution of the plurality of resource files. For embodiments in which a virtual machine is streamed or otherwise downloaded to the client machine, a license pool may be provided that authorizes the virtual machine, its guest operating system and all the licensed software installed within that guest operating system. In some of these embodiments, a single license is provided that authorizes those entities.

0657In another embodiment, the client machine <b>10</b> receives from the remote machine <b>30</b> the license and an identifier associated with a remote machine <b>30</b> monitoring execution of the plurality of resource files. In some embodiments, the remote machine <b>30</b> is a session management server <b>1962</b>, as described below in connection with <figref idref="DRAWINGS">FIG. 19</figref>. In one of these embodiments, the session management server <b>1962</b> includes a session management subsystem <b>1910</b> that monitors the session associated with the client machine <b>10</b>. In other embodiments, a separate remote machine <b>30</b>″″ is the session management server <b>1962</b>.

0658Referring back to <figref idref="DRAWINGS">FIG. 18</figref>, the client machine <b>10</b> receives and executes the plurality of resource files (step <b>1814</b>). In one embodiment, the client machine <b>10</b> receives the plurality of resource files across a resource streaming session. In another embodiment, the client machine <b>10</b> stores the plurality of resource files in an isolation environment on the client machine <b>10</b>. In still another embodiment, the client machine <b>10</b> executes one of the plurality of resource files prior to receiving a second of the plurality of resource files. In some embodiments, a remote machine <b>30</b> transmits the plurality of resource files to a plurality of client machines <b>10</b>, each client machine <b>10</b> in the plurality having established a separate resource streaming session with the remote machine <b>30</b>.

0659In some embodiments, the client machine <b>10</b> stores the plurality of resource files in a cache and delays execution of the resource files. In one of these embodiments, the client machine <b>10</b> receives authorization to execute the resource files during a pre-defined period of time. In another of these embodiments, the client machine <b>10</b> receives authorization to execute the resource files during the pre-defined period of time when the client machine <b>10</b> lacks access to a network. In other embodiments, the client machine <b>10</b> stores the plurality of resource files in a cache. In one of these embodiments, a resource streaming client <b>1952</b> (described in further detail below in connection with <figref idref="DRAWINGS">FIG. 19</figref>) establishes an internal resource streaming session to retrieve the plurality of resource files from the cache. In another of these embodiments, the client machine <b>10</b> receives authorization to execute the resource files during a pre-defined period of time when the client machine <b>10</b> lacks access to a network.

0660The client machine <b>10</b> transmits at least one heartbeat message to a remote machine (step <b>1816</b>). In some embodiments, the client machine <b>10</b> transmits the at least one heartbeat message to retain authorization to execute the plurality of resource files comprising the enumerated resource. In other embodiments, the client machine <b>10</b> transmits the at least one heartbeat message to retain authorization retrieve a resource file in the plurality of resource files. In still other embodiments, the client machine <b>10</b> receives a license authorizing execution of the plurality of resource files during a pre-determined period of time.

0661In some embodiments, the client machine <b>10</b> transmits the heartbeat message to a second remote machine <b>30</b>″″. In one of these embodiments, the second remote machine <b>30</b>″″ may comprise a session management server <b>1962</b> monitoring the retrieval and execution of the plurality of resource files. In another of these embodiments, the second remote machine <b>30</b>″″ may renew a license authorizing execution of the plurality of resource files, responsive to the transmitted heartbeat message. In still another of these embodiments, the second remote machine <b>30</b>″″ may transmit to the client machine <b>10</b> a command, responsive to the transmitted heartbeat message.

0662Referring now to <figref idref="DRAWINGS">FIG. 19</figref>, the client machine <b>10</b> may include a resource streaming client <b>1952</b>, a streaming service <b>1954</b> and an isolation environment <b>1956</b>.

0663The resource streaming client <b>1952</b> may be an executable program. In some embodiments, the resource streaming client <b>1952</b> may be able to launch another executable program. In other embodiments, the resource streaming client <b>1952</b> may initiate the streaming service <b>1954</b>. In one of these embodiments, the resource streaming client <b>1952</b> may provide the streaming service <b>1954</b> with a parameter associated with executing a resource. In another of these embodiments, the resource streaming client <b>1952</b> may initiate the streaming service <b>1954</b> using a remote procedure call.

0664In one embodiment, the client machine <b>10</b> requests execution of a resource and receives access information from a remote machine <b>30</b> regarding execution. In another embodiment, the resource streaming client <b>1952</b> receives the access information. In still another embodiment, the resource streaming client <b>1952</b> provides the access information to the streaming service <b>1954</b>. In yet another embodiment, the access information includes an identification of a location of a file associated with a plurality of resource files comprising the resource.

0665In one embodiment, the streaming service <b>1954</b> retrieves a file associated with a plurality of resource files. In some embodiments, the retrieved file includes an identification of a location of the plurality of resource files. In one of these embodiments, the streaming service <b>1954</b> retrieves the plurality of resource files. In another of these embodiments, the streaming service <b>1954</b> executes the retrieved plurality of resource files on the client machine <b>10</b>. In other embodiments, the streaming service <b>1954</b> transmits heartbeat messages to a remote machine <b>30</b> to maintain authorization to retrieve and execute a plurality of resource files.

0666In some embodiments, the retrieved file includes an identification of a location of more than one plurality of resource files, each plurality of resource files comprising a different resource. In one of these embodiments, the streaming service <b>1954</b> retrieves the plurality of resource files comprising the resource compatible with the client machine <b>10</b>. In another of these embodiments, the streaming service <b>1954</b> receives authorization to retrieve a particular plurality of resource files, responsive to an evaluation of the client machine <b>10</b>.

0667In some embodiments, the plurality of resource files are compressed and stored on a file server within an archive file such as a CAB, ZIP, SIT, TAR, JAR or other archive file. In one embodiment, a plurality of resource files stored in an archive file comprises a resource. In another embodiment, multiple pluralities of resource files stored in an archive file each comprise different versions of a resource. In still another embodiment, multiple pluralities of resource files stored in an archive file each comprise different resources. In some embodiments, an archive file includes metadata associated with each file in the plurality of resource files. In one of these embodiments, the streaming service <b>1954</b> generates a directory structure responsive to the included metadata. As will be described in greater detail below, the metadata may be used to satisfy requests by resources for directory enumeration.

0668In one embodiment, the streaming service <b>1954</b> decompresses an archive file to acquire the plurality of resource files. In another embodiment, the streaming service <b>1954</b> determines whether a local copy of a file within the plurality of resource files exists in a cache on the client machine <b>10</b> prior to retrieving the file from the plurality of resource files. In still another embodiment, the file system filter driver <b>1964</b> determines whether the local copy exists in the cache. In some embodiments, the streaming service <b>1954</b> modifies a registry entry prior to retrieving a file within the plurality of resource files.

0669In some embodiments, the streaming service <b>1954</b> stores a plurality of resource files in a cache on the client machine <b>10</b>. In one of these embodiments, the streaming service <b>1954</b> may provide functionality for caching a plurality of resource files upon receiving a request to cache the plurality of resource files. In another of these embodiments, the streaming service <b>1954</b> may provide functionality for securing a cache on the client machine <b>10</b>. In another of these embodiments, the streaming service <b>1954</b> may use an algorithm to adjust a size and a location of the cache.

0670In some embodiments, the streaming service <b>1954</b> creates an isolation environment <b>1956</b> on the client machine <b>10</b>. In one of these embodiments, the streaming service <b>1954</b> uses an isolation environment application programming interface to create the isolation environment <b>1956</b>. In another of these embodiments, the streaming service <b>1954</b> stores the plurality of resource files in the isolation environment <b>1956</b>. In still another of these embodiments, the streaming service <b>1954</b> executes a file in the plurality of resource files within the isolation environment. In yet another of these embodiments, the streaming service <b>1954</b> executes the resource in the isolation environment. In some embodiments, the streaming service <b>1954</b> accesses an isolation environment <b>1956</b> provided by a virtual machine.

0671For embodiments in which authorization is received to execute a resource on the client machine <b>10</b>, the execution of the resource may occur within an isolation environment <b>1956</b>. In some embodiments, a plurality of resource files comprising the resource is stored on the client machine <b>10</b> prior to execution of the resource. In other embodiments, a subset of the plurality of resource files is stored on the client machine <b>10</b> prior to execution of the resource. In still other embodiments, the plurality of resource files does not reside in the isolation environment <b>1956</b>. In yet other embodiments, a subset of the plurality of resources files do not reside on the client machine <b>10</b>. Regardless of whether a subset of the plurality of resource files or each resource file in the plurality of resource files reside on the client machine <b>10</b> or in isolation environment <b>1956</b>, in some embodiments, a resource file in the plurality of resource files may be executed within an isolation environment <b>1956</b>.

0672In some embodiments, isolation environments are used to provide additional functionality to the resource streaming client <b>1952</b>. In one of these embodiments, a resource is executed within an isolation environment. In another of these embodiments, a retrieved plurality of resource files resides within the isolation environment. In still another of these embodiments, changes to a registry on the client machine <b>10</b> are made within the isolation environment.

0673In one embodiment, the resource streaming client <b>1952</b> includes an isolation environment <b>1956</b>. In some embodiments, the resource streaming client <b>1952</b> includes a file system filter driver <b>1964</b> intercepting resource requests for files. In one of these embodiments, the file system filter driver <b>1964</b> intercepts a resource request to open an existing file and determines that the file does not reside in the isolation environment <b>1956</b>. In another of these embodiments, the file system filter driver <b>1964</b> redirects the request to the streaming service <b>1954</b> responsive to a determination that the file does not reside in the isolation environment <b>1956</b>. The streaming service <b>1954</b> may extract the file from the plurality of resource files and store the file in the isolation environment <b>1956</b>. The file system filter driver <b>1964</b> may then respond to the request for the file with the stored copy of the file. In some embodiments, the file system filter driver <b>1964</b> may redirect the request for the file to a file server <b>1940</b>, responsive to an indication that the streaming service <b>1954</b> has not retrieved the file or the plurality of resource files and a determination the file does not reside in the isolation environment <b>1956</b>.

0674In some embodiments, the file system filter driver <b>1964</b> uses a strict isolation rule to prevent conflicting or inconsistent data from appearing in the isolation environment <b>1956</b>. In one of these embodiments, the file system filter driver <b>1964</b> intercepting a request for a resource in a user isolation environment may redirect the request to a resource isolation environment. In another of these embodiments, the file system filter driver <b>1964</b> does not redirect the request to a system scope.

0675In one embodiment, the streaming service <b>1954</b> uses IOCTL commands to communicate with the filter driver. In another embodiment, communications to the file server <b>1940</b> are received with the Microsoft SMB streaming protocol.

0676Referring now to <figref idref="DRAWINGS">FIG. 20</figref>, a flow diagram depicts one embodiment of steps taken by a client machine <b>10</b> to execute a resource. As described above in <figref idref="DRAWINGS">FIG. 18</figref>, regarding step <b>1814</b>, a client machine <b>10</b> receives and executes the plurality of resource files. In brief overview, the client machine <b>10</b> receives a file including access information for accessing a plurality of resource files and for executing a first client capable of receiving a resource stream (step <b>2002</b>). The client machine <b>10</b> retrieves an identification of the plurality of resource files, responsive to the file (step <b>2004</b>). The client machine <b>10</b> retrieves at least one characteristic required for execution of the plurality of resource files, responsive to the file (step <b>2006</b>). The client machine <b>10</b> determines whether the client machine <b>10</b> includes the at least one characteristic (step <b>2008</b>). The client machine <b>10</b> executes a second client, the second client requesting execution of the plurality of resource files on a remote machine <b>30</b>, responsive to a determination that the client machine <b>10</b> lacks the at least one characteristic (step <b>2010</b>).

0677Referring to <figref idref="DRAWINGS">FIG. 20</figref>, and in greater detail, the client machine <b>10</b> receives a file including access information for accessing a plurality of resource files and for executing a first client capable of receiving a resource stream (step <b>2002</b>). In one embodiment, the client machine <b>10</b> receives access information including an identification of a location of a plurality of resource files comprising a resource. In another embodiment, the client machine <b>10</b> receives the file responsive to requesting execution of the resource. In still another embodiment, the access information includes an indication that the plurality of resource files reside on a remote machine <b>30</b>′ such as a resource server or a file server. In yet another embodiment, the access information indicates that the client machine <b>10</b> may retrieve the plurality of resource files from the remote machine <b>30</b> over a resource streaming session.

0678The client machine <b>10</b> retrieves an identification of the plurality of resource files, responsive to the file (step <b>2004</b>). In one embodiment, the client machine <b>10</b> identifies a remote machine <b>30</b> on which the plurality of resource files resides, responsive to the file including access information. In another embodiment, the client machine <b>10</b> retrieves from the remote machine <b>30</b> a file identifying the plurality of resource files. In some embodiments, the plurality of resource files comprises a resource. In other embodiments, the plurality of resource files comprises multiple resources. In still other embodiments, the plurality of resource files comprises multiple versions of a single resource.

0679Referring ahead to <figref idref="DRAWINGS">FIG. 21</figref>, a block diagram depicts one embodiment of a plurality of resource files residing on a remote machine <b>30</b>′, such as file server <b>1940</b>. In <figref idref="DRAWINGS">FIG. 21</figref>, a plurality of resource files, referred to as a package, includes resource files comprising three different versions of one or more resources.

0680In one embodiment, each subset of resource files comprising a version of one or more resources and stored within the package is referred to as a target. Target <b>1</b>, for example, includes a version of a word processing resource and of a spreadsheet program, the version compatible with the English language version of the Microsoft Windows 2000 operating system. Target <b>2</b> includes a version of a word processing resource and of a spreadsheet program, the version compatible with the English language version of the Microsoft XP operating system. Target <b>3</b> a version of a word processing resource and of a spreadsheet program, the version compatible with the Japanese language version of the Microsoft Windows 2003 operating system with service pack 3.

0681Returning back to <figref idref="DRAWINGS">FIG. 20</figref>, in some embodiments, the file retrieved from the remote machine <b>30</b> hosting the plurality of resource files includes a description of the package and the targets included in the plurality of resource files. In other embodiments, the file retrieved from the remote machine <b>30</b> identifies the plurality of resource files comprising a resource requested for execution by the client machine <b>10</b>.

0682The client machine <b>10</b> retrieves at least one characteristic required for execution of the plurality of resource files, responsive to the file (step <b>2006</b>). In some embodiments, the client machine <b>10</b> may not execute a resource unless the client machine <b>10</b> includes certain characteristics. In one of these embodiments, different resources require client machines <b>10</b> to include different characteristics from the characteristics required by other resources. In another of these embodiments, the client machine <b>10</b> receives an identification of the at least one characteristic required for execution of the plurality of resource files comprising the resource requested by the client machine <b>10</b>.

0683Still referring to <figref idref="DRAWINGS">FIG. 20</figref>, the client machine <b>10</b> determines whether the client machine <b>10</b> includes the at least one characteristic (step <b>2008</b>). In one embodiment, the client machine <b>10</b> evaluates an operating system on the client machine <b>10</b> to determine whether the client machine <b>10</b> includes the at least one characteristic. In another embodiment, the client machine <b>10</b> identifies a language used by an operating system on the client machine <b>10</b> to determine whether the client machine <b>10</b> includes the at least one characteristic. In still another embodiment, the client machine <b>10</b> identifies a revision level of an operating system on the client machine <b>10</b> to determine whether the client machine <b>10</b> includes the at least one characteristic. In yet another embodiment, the client machine <b>10</b> identifies a resource version of a resource residing on the client machine <b>10</b> to determine whether the client machine <b>10</b> includes the at least one characteristic. In some embodiments, the client machine <b>10</b> determines whether the client machine <b>10</b> includes a device driver to determine whether the client machine <b>10</b> includes the at least one characteristic. In other embodiments, the client machine <b>10</b> determines whether the client machine <b>10</b> includes an operating system to determine whether the client machine <b>10</b> includes the at least one characteristic. In still other embodiments, the client machine <b>10</b> determines whether the client machine <b>10</b> includes a license to execute the plurality of resource files to determine whether the client machine <b>10</b> includes the at least one characteristic.

0684In one embodiment, the client machine <b>10</b> determines whether the client machine <b>10</b> comprises a required amount of available disk space to access the resource. In another embodiment, the client machine <b>10</b> determines whether a central processing unit of the client machine <b>10</b> provides a required processing speed. In still another embodiment, the client machine <b>10</b> determines whether the client machine <b>10</b> comprises a required amount of available RAM. In yet another embodiment, the client machine <b>10</b> determines whether the client machine <b>10</b> comprises a required level of graphical processing and display capabilities.

0685The client machine <b>10</b> executes a second client, the second client requesting execution of the plurality of resource files on a remote machine <b>30</b>, responsive to a determination that the client machine <b>10</b> lacks the at least one characteristic (step <b>2010</b>). In one embodiment, when the client machine <b>10</b> determines that the client machine <b>10</b> lacks the at least one characteristic, the client machine <b>10</b> does not execute the first client capable of receiving a resource stream. In another embodiment, a policy prohibits the client machine <b>10</b> from receiving the plurality of resource files over a resource stream when the client machine <b>10</b> lacks the at least one characteristic. In some embodiments, the client machine <b>10</b> determines that the client machine <b>10</b> does include the at least one characteristic. In one of these embodiments, the client machine <b>10</b> executes the first client, the first client receiving a resource stream comprising the plurality of resource files from a remote machine <b>30</b> for execution on the client machine <b>10</b>.

0686In some embodiments, the client machine <b>10</b> executes the second client requesting execution of the plurality of resource files on a remote machine <b>30</b> upon determining that the client machine <b>10</b> lacks the at least one characteristic. In one of these embodiments, the second client transmits the request to a remote machine <b>30</b> hosting the plurality of resource files. In another of these embodiments, the remote machine <b>30</b> executes the plurality of resource files comprising the resource and generates resource-output data. In still another of these embodiments, the second client receives resource-output data generated by execution of the plurality of resource files on the remote machine <b>30</b>. In yet another of these embodiments, the second client displays the resource-output on the client machine <b>10</b>. In one embodiment, the client machine <b>10</b> requests execution of the plurality of application files on a physical machine <b>30</b>. In another embodiment, the client machine <b>10</b> requests execution of the plurality of application files on a virtual machine executing on a remote machine <b>30</b>.

0687In some embodiments, the second client receives a file comprising access information for accessing a plurality of resource files and requests, responsive to a determination by the first client that the client machine <b>10</b> lacks the at least one characteristic, execution of the plurality of resource files on a virtual machine providing a computing environment having the least one characteristic. In other embodiments, the client machine <b>10</b> executes the second client requesting execution of the plurality of resource files on a remote machine <b>30</b> upon determining that the client machine <b>10</b> lacks the at least one characteristic. In one of these embodiments, the second client transmits the request to a remote machine <b>30</b> hosting the plurality of resource files. In another of these embodiments, a virtual machine executing on the remote machine <b>30</b> executes the plurality of resource files comprising the resource and generates resource-output data. In still another of these embodiments, the second client receives resource-output data generated by execution of the plurality of resource files on the virtual machine. In yet another of these embodiments, the second client displays the resource-output on the client machine <b>10</b>.

0688In some embodiments, the second client transmits the request to a remote machine <b>30</b> that does not host the plurality of resource files. In one of these embodiments, the remote machine <b>30</b> may request the plurality of resource files from a second remote machine <b>30</b> hosting the plurality of resource files. In another of these embodiments, the remote machine <b>30</b> may receive the plurality of resource files from the second remote machine <b>30</b> across a resource streaming session. In still another of these embodiments, the remote machine <b>30</b> stores the received plurality of resource files in an isolation environment and executes the resource within the isolation environment. In yet another of these embodiments, the remote machine <b>30</b> transmits the generated resource-output data to the second client on the client machine <b>10</b>.

0689In some embodiments, the second client transmits the request to a remote machine <b>30</b> that does not host the plurality of resource files. In one of these embodiments, the remote machine <b>30</b> may request the plurality of resource files from a second remote machine <b>30</b> hosting the plurality of resource files. In another of these embodiments, the remote machine <b>30</b> may receive the plurality of resource files from the second remote machine <b>30</b> across a resource streaming session.

0690In other embodiments, the remote machine <b>30</b> stores the received plurality of resource files in a computing environment provided by a virtual machine executing on the remote machine <b>30</b>, the computing environment having the at least one characteristic. In yet another of these embodiments, the remote machine <b>30</b> executes the resource within the computing environment provided by the virtual machine and transmits the generated resource-output data to the second client on the client machine <b>10</b>.

0691In some embodiments, a virtual machine on the remote machine <b>30</b> executes the plurality of resource files. In one of these embodiments, the virtual machine receives for execution a resource stream comprising the plurality of resource files. In some embodiments, a virtual machine may receive for execution a resource stream responsive to an application of a policy. In one of these embodiments, the result of the application of the policy depends on an availability of the requested resource in the machine farm <b>38</b> (including availability of a suitably configured physical machine <b>30</b> or virtual machine), the sensitivity of the requested resource (including whether a policy prevents the transmission of the requested resource to an unsecured environment), information associated with the user of the client machine <b>10</b> (including authorization to execute or access the requested resource in an unsecured environment).

0692Referring back to <figref idref="DRAWINGS">FIG. 19</figref>, in one embodiment, the first client machine <b>10</b>, capable of receiving the resource stream, is a resource streaming client <b>1952</b>. The resource streaming client <b>1952</b> receiving the file, retrieving an identification of a plurality of resource files and at least one characteristic required for execution of the plurality of resource files, responsive to the file, and determining whether the client machine <b>10</b> includes the at least one characteristic. In another embodiment, the second client is a client agent <b>1960</b>. In some embodiments, the client agent <b>1960</b> receives the file from the resource streaming client <b>1952</b> responsive to a determination, by the resource streaming client <b>1952</b>, that the client machine <b>10</b> lacks the at least one characteristic.

0693A remote machine <b>30</b> includes functionality for monitoring resource usage by a client machine <b>10</b>. The remote machine <b>30</b> may monitor the status of each resource used by the client machine <b>10</b>, for example upon execution or termination of a resource. In one embodiment, the remote machine <b>30</b> requires the client machine <b>10</b> to transmit messages about the status of a resource executed by the client machine <b>10</b>. In another embodiment, when a client machine <b>10</b> connects to a network on which the remote machine <b>30</b> resides, the client machine <b>10</b> transmits a message indicating that the client machine <b>10</b> has connected to the network.

0694In one embodiment, the client machine <b>10</b> is said to have a session when the client machine <b>10</b> interacts with the remote machine <b>30</b> and executes one or more resources. In another embodiment, the remote machine <b>30</b> requires the client machine <b>10</b> to maintain, for the duration of a session, a license authorizing execution of resources received from a remote machine <b>30</b>. In still another embodiment, sessions have unique session identifiers assigned by the remote machine <b>30</b>.

0695In one embodiment, the client machine <b>10</b> transmits the messages to the remote machine <b>30</b> with which it interacted to receive and execute the resource. In another embodiment, the client machine <b>10</b> receives from the remote machine <b>30</b> an identifier of a second remote machine <b>30</b>, such as a session management server <b>1962</b>, the second remote machine <b>30</b> receiving and storing all transmitted messages associated with the session on the client machine <b>10</b>.

0696In some embodiments, the session management server <b>1962</b> is a remote machine <b>30</b> providing license management and session monitoring services. In one of these embodiments, the session management server <b>1962</b> includes a server management subsystem <b>1908</b> providing these services.

0697In one embodiment, the client machine <b>10</b> transmits messages directly to the session management server <b>1962</b>. In another embodiment, the client machine <b>10</b> transmits messages to a remote machine <b>30</b>, the remote machine <b>30</b> forwarding the messages to the session management server <b>1962</b> with an identification of the client machine <b>10</b>.

0698A client machine <b>10</b> may transmit a heartbeat message to the remote machine <b>30</b>. In one embodiment, the heartbeat message includes a request for a license. In this embodiment, the client machine <b>10</b> may transmit the heartbeat message after receiving access information associated with a resource which the client machine <b>10</b> requested authorization to execute. The client machine <b>10</b> may transmit the heartbeat message prior to executing the resource. In one embodiment, the client machine <b>10</b> includes with the heartbeat message a launch ticket received with the access information. In this embodiment, the remote machine <b>30</b> may grant the client machine <b>10</b> a license upon successful verification of the launch ticket.

0699In another embodiment, the heartbeat message includes an indication that the client machine <b>10</b> has initiated execution of a resource. In still another embodiment, the heartbeat message includes an indication that the client machine <b>10</b> has terminated execution of a resource. In yet another embodiment, the heartbeat message includes an indication of a failure to execute a resource.

0700In one embodiment, the heartbeat message includes a request for an identification of a second session management server, such as a session management server <b>1962</b>. In another embodiment, the heartbeat message includes an indication that the client machine <b>10</b> has connected to a network on which the remote machine <b>30</b> resides.

0701In some embodiments, the heartbeat message includes a request to reset a resource streaming session. In one of these embodiments, the client machine <b>10</b> transmits this heartbeat message when an error has occurred and a connection is terminated between a network on which the remote machine <b>30</b> resides and the client machine <b>10</b>. In another of these embodiments, the client machine <b>10</b> transmits with the heartbeat message information associated with the session. In still another of these embodiments, the remote machine <b>30</b> may transmit to the client machine <b>10</b> session-related data if the session has not expired.

0702In another of these embodiments, if a remote machine <b>30</b> disconnects from a network on which it replies, the client machine <b>10</b> may not receive a reply to a heartbeat message transmitted to the remote machine <b>30</b>. In one embodiment, the client machine <b>10</b> may re-establish a session by transmitting a message requesting a session reset to the remote machine <b>30</b>. In another embodiment, the client machine <b>10</b> may re-establish a session by transmitting a message requesting a session reset to a second remote machine <b>30</b>. In some embodiments, when the remote machine <b>30</b> reconnects to the network, it will create a new session for each session reset request received while the remote machine <b>30</b> was disconnected. In one of these embodiments, the new session will be associated with the reconnected and unlicensed state. In another of these embodiments, no new license will be acquired for the new session. In still another of these embodiments, when the client machine <b>10</b> executes a resource, a new license will be acquired and all sessions associated with the client machine <b>10</b> will be associated with an active and licensed state.

0703In some embodiments, a resource streaming client <b>1952</b> on the client machine <b>10</b> generates the heartbeat message. In one of these embodiments, the resource streaming client <b>1952</b> forwards the heartbeat message to a web interface <b>1958</b> for transmission to the client machine <b>10</b> for transmission to the remote machine <b>30</b>. In other embodiments, the management service <b>1904</b> on the remote machine <b>30</b> receives the heartbeat message from the client machine <b>10</b> via the web interface <b>1958</b>. In still other embodiments, a remote machine <b>30</b> comprising a collector point <b>240</b> (described above) receives and stores the heartbeat messages.

0704In some embodiments, the resource streaming client <b>1952</b> requests a license from the remote machine <b>30</b>. In one of these embodiments, the license authorizes execution of a resource on the client machine <b>10</b>. In another of these embodiments, the remote machine <b>30</b> may access a second remote machine <b>30</b> to provide the license. In still another of these embodiments, the remote machine <b>30</b> may provide the license to the client machine <b>10</b>. In yet another of these embodiments, the remote machine <b>30</b> may provide a license acceptable for authorization purposes to a second remote machine <b>30</b>. In some embodiments, the license is revoked upon termination of execution of a resource.

0705Referring back to <figref idref="DRAWINGS">FIG. 8</figref>, a request for access to a resource is received (step <b>802</b>). In some embodiments, the resource is a file. In one of these embodiments, an application program is selected and executed to provide access to the file. In another of these embodiments, a type of file associated with the requested file is identified to select an application program for execution. In still another of these embodiments, prior to the request for access to the file, an application program is associated with a type of file, enabling automatic selection of the application program upon identification of a type of file associated with the requested file. In some embodiments, file type association (FTA) functionality permits users to automatically initiate the execution of application programs associated with a data file, even though the data file and the executable program are hosted on different computing nodes.

0706Typically, file type association functionality permits users to transparently execute executable programs by selecting data files located on a computing machine that differs from the machine(s) where the executable programs are located. In one embodiment, a user of a client machine <b>10</b> can transparently invoke the execution of an executable program on a remote machine <b>30</b> by selecting a data file located on the client machine <b>10</b>. In another embodiment, a user can transparently invoke the execution of an application program on their client machine <b>10</b> by selecting a data file located on a remote machine <b>30</b>. In still another embodiment, a user can select a data file stored on a remote machine <b>30</b>′, such as a web server, and transparently invoke the execution of an associated executable program on a remote machine <b>30</b>, such as an application execution server. Typically, execution permits processing of the contents of the selected data file, the output of which is then provided to the user at the client machine <b>10</b>.

0707It is to be understood that examples using filename extensions necessarily reflect the idiosyncrasies of embodiments utilizing the WINDOWS family of operating systems. Other embodiments implement methods and apparatus in accord using special parameters stored in the data file itself, the data contained in the data file, the file system records associated with the data file, or a separate data file or database. For example, embodiments using the MacOS family of operating systems utilize file and application creator types and store file-type association data in the Desktop file associated with each storage device. Embodiments using a UNIX-variant operating system utilize file extensions, embedded parameters, or other mechanisms as appropriate. Accordingly, the scope of the claims should not be read to be limited to embodiments relying on filename extensions or embodiments utilizing WINDOWS operating systems.

Client-Based FTA

0708Referring to <figref idref="DRAWINGS">FIG. 22A</figref>, a flow diagram depicts one embodiment of the steps taken in a method of enabling transparent distributed program execution on a remote machine <b>30</b> through the selection of graphical indicia representative of a data file located on the client machine <b>10</b>. The client machine <b>10</b> receives, from one of a plurality of remote machines <b>30</b>, a mapping specifying an association between a type of data file and an executable program for execution on one of a plurality of remote machines <b>30</b> (Step <b>2206</b>). In some embodiments, the mapping specifies an association between a type of data file and an executable program for execution on a virtual machine located on one of a plurality of remote machines <b>30</b>.

0709The client machine <b>10</b> presents a graphical depiction of a data file stored on the client machine <b>10</b> (Step <b>2214</b>) and receives a selection of the graphical depiction of the data file (Step <b>2218</b>). The client machine <b>10</b> identifies an executable program associated with the type of the selected data file using the received mapping (Step <b>2222</b>) and sends a request to a remote machine <b>30</b> for execution of the identified executable program (Step <b>2226</b>). In one embodiment, the client machine <b>10</b> initiates the execution of a local display application (Step <b>2230</b>) to receive application output data from the executing program (Step <b>2234</b>), which it displays to the end user (Step <b>2238</b>).

0710Still referring to <figref idref="DRAWINGS">FIG. 22A</figref>, when the client, machine <b>10</b> receives the mapping (Step <b>106</b>), the mapping may be received by itself, with several other mappings, or with other messages or data such as software updates. Table 3 illustrates an exemplary mapping provided in one embodiment of the invention:

0000<tables id="TABLE-US-00006" num="00006"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="35pt" align="left" /><colspec colname="1" colwidth="84pt" align="left" /><colspec colname="2" colwidth="98pt" align="left" /><thead><row><entry /><entry namest="offset" nameend="2" rowsep="1">TABLE 3</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row><row><entry /><entry>File type:</entry><entry>Executable program:</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>“.DOC”, “.RTF”</entry><entry>MSWORD.EXE</entry></row><row><entry /><entry>“.PDF”</entry><entry>ACROBAT.EXE</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0711In one embodiment, the mapping identifies an association between a particular executable program for use with a particular data file or type of data file stored on the user's client machine <b>10</b>. In another embodiment, the mapping specifies the relationship between an executable program and a data file in terms of a client machine <b>10</b> application that launches the executable program on a remote machine <b>30</b> and displays the output from execution at the client machine <b>10</b>. For example, as described in connection with <figref idref="DRAWINGS">FIG. 8A</figref> (step <b>2206</b>), the mapping could specify that when a “.DOC” file is selected, the client machine <b>10</b> is to execute METAFRAME from Citrix Software of Ft. Lauderdale, Fla., which in turn sends a request to one of a plurality of remote machines <b>30</b> to execute WORD, receiving the output data from execution for display to the user at the client machine <b>10</b>. In some embodiments, a remote machine <b>30</b> receiving the request to execute the application program chooses a method for providing access to the application program, as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref> (step <b>804</b>). In one of these embodiments, the remote machine <b>30</b> determines to execute the application and provide the application output data to the client machine <b>10</b>. In another of these embodiments, the remote machine <b>30</b> identifies a remote machine <b>30</b> that executes the application and provides the application output data to the client machine <b>10</b>. In still another of these embodiments, the remote machine <b>30</b> identifies an application streaming service that transmits the application program to the client machine <b>10</b> for local execution. In yet another of these embodiments, the remote machine <b>30</b> identifies a remote machine <b>30</b>′ on which a virtual machine provides a computing environment capable of executing the application program and transmitting the application output data to the client machine <b>10</b>.

0712In still another embodiment, mapping specifies the relationship between an executable program and a data file in terms of a client machine <b>10</b> application that requests transmission of the executable program to the client machine <b>10</b> from an application streaming service provided by a remote machine <b>30</b>. In other embodiments, the mapping could specify that when a file is selected, the client machine <b>10</b> is to establish a connection to a virtual machine provided by one of a plurality of remote machines <b>30</b> to initiate execution of an application program on the virtual machine and to receive application output data from the execution for display to the user at client machine <b>10</b>. In some of these embodiments, as described in connection with <figref idref="DRAWINGS">FIG. 8</figref> (step <b>808</b>), a virtual machine and an execution machine onto which the virtual machine is launched are identified, configured, and provide the user of the client machine <b>10</b> with access to the file.

0713In some embodiments, the client machine <b>10</b> displays a list of file names associated with data files stored on the client machine <b>10</b>. In still another embodiment, indicia representative of files stored on the client machine <b>10</b> are intermingled with indicia representative of files stored on one or more remote machines <b>30</b>, or on virtual machines executing on remote machines <b>30</b>. In this embodiment, client-based FTA is operative when indicia representative of a file stored on the client machine <b>10</b> is selected. In another embodiment, multiple forms of FTA (see below) are operative, with the appropriate form of FTA activated based on the location of the file associated with the selected indicia.

0714<figref idref="DRAWINGS">FIG. 22B</figref> illustrates one embodiment of the steps taken by a remote machine <b>30</b> in the client-based file-type association process. A mapping is provided specifying an association between a type of data file stored on a client machine <b>10</b> and an executable program for execution on one of a plurality of remote machines <b>30</b> (Step <b>2254</b>). A request to execute the executable program is received (Step <b>2262</b>) and the executable program is executed on one of a plurality of remote machines <b>30</b> (Step <b>2266</b>). In one embodiment, the remote machine <b>30</b> receiving the request to execute the executable program chooses to provide the requested access as describe above in connection with <figref idref="DRAWINGS">FIG. 8</figref> (step <b>2204</b> and step <b>2206</b>). In some embodiments, the remote machine <b>30</b> receives a request for transmission of the identified executable program to the client machine <b>10</b> for local execution. In one of these embodiments, the remote machine <b>30</b> chooses to provide the client machine <b>10</b> with the executable program via an application streaming service as described above. In another of these embodiments, the remote machine <b>30</b> chooses to stream the executable program to a remote machine <b>30</b> or to a virtual machine executing on a remote machine <b>30</b>′.

Server-Based FTA

0715Referring now to <figref idref="DRAWINGS">FIG. 23</figref>, a flow diagram depicts another embodiment of the steps taken in a method for enabling transparent distributed program execution on a client machine <b>10</b> through the selection of graphical indicia representative of a data file located on a remote machine <b>30</b>. The client machine <b>10</b> presents a graphical depiction of a data file stored on one of a plurality of remote machines <b>30</b> (Step <b>2300</b>). The client machine <b>10</b> receives a selection of the graphical depiction of the data file (Step <b>2304</b>) and transmits the selection to one of the plurality of remote machines <b>30</b> (Step <b>2308</b>). The client machine <b>10</b> receives a request from one of the plurality of remote machines <b>30</b> to execute an executable program associated with the selected data file (Step <b>2312</b>) and executes the associated executable program (Step <b>2316</b>).

0716Still referring to <figref idref="DRAWINGS">FIG. 23</figref>, the client machine <b>10</b> presents a user with a graphical depiction of at least one data file stored on at least one remote machine <b>30</b> (Step <b>2300</b>). In one embodiment, indicia representative of files stored on one or more remote machines <b>30</b>, and on virtual machines executing on the one or more remote machines <b>30</b>, are intermingled with indicia representative of files stored on the client machine <b>10</b>. In this embodiment, server-based FTA is operative when indicia representative of a file stored on a remote machine <b>30</b> is selected. In another embodiment, multiple forms of FTA (see above, below) are operative, with the appropriate form of FTA activated based on the location of the file associated with the selected graphical indicia.

0717As described above in connection with <figref idref="DRAWINGS">FIG. 8</figref> (step <b>804</b>), a remote machine <b>30</b> receiving a request to access a selected data file chooses a method for providing access to the data file. In one embodiment, the data file resides on the remote machine <b>30</b>. In another embodiment, the data file resides on a remote machine <b>30</b>′, such as a web server. In some embodiments, the remote machine <b>30</b> consults a mapping to identify an application program associated with the requested data file.

0718In some embodiments, the remote machine <b>30</b> chooses to provide the client machine <b>10</b> with access to the file via execution of the associated application program in a computing environment provided by a virtual machine (step <b>806</b>). In one of these embodiments, the remote machine <b>30</b> may identify a remote machine <b>30</b>′ to execute the application program and transmit application output data to the client machine <b>10</b>. In another of these embodiments, the remote machine <b>30</b> identifies a remote machine <b>30</b>′ to execute the application program in a computing environment provided by a virtual machine executing on the remote machine <b>30</b>′, as described in connection with <figref idref="DRAWINGS">FIG. 8</figref> (step <b>808</b>).

0719In other embodiments, the remote machine <b>30</b> identifies a remote machine <b>30</b>′ providing an application streaming service capable of transmitting the application program to the client machine <b>10</b> for execution on the client machine <b>10</b> as described in connection with <figref idref="DRAWINGS">FIG. 8</figref> (step <b>816</b>). In one of these embodiments, the application streaming service transmits the application program to a remote machine <b>30</b>′ for execution and the remote machine <b>30</b> transmits application output data resulting from the execution to the client machine <b>10</b>.

0720In some embodiments, the remote machine <b>30</b> selects one of a predetermined number of methods for executing a requested application program, responsive to a policy, the predetermined number of methods including a method for executing the requested application in a computing environment provided by a virtual machine. In one of these embodiments, the application streaming service transmits the application program to a remote machine <b>30</b>′ for executing in a computing environment provided by a virtual machine executing in the remote machine <b>30</b>′. In another of these embodiments, the remote machine <b>30</b> selects a method for streaming the requested application program to a virtual machine and executing the enumerated application in the virtual machine environment. In still another of these embodiments, the virtual machine is evaluated and, a determination to stream the requested application is made responsive to the evaluation. In other embodiments, the determination to stream one of a plurality of files comprising an enumerated application program to a virtual machine is made responsive to credentials gathered from a client machine <b>10</b>.

0721Having received data associated with the selected data file, the client machine <b>10</b> typically processes the received data using the executing program and displays the result of the processing to the end user.

0722As described above, a client machine <b>10</b> connects to one or more of the remote machines <b>30</b> in the machine farm <b>38</b>. In some of these embodiments, the client machine <b>10</b> may communicate with remote machines <b>30</b> to receive application-output data generated by an execution of an application program on a remote machine <b>30</b>, or on a virtual machine executing on the remote machine <b>30</b>. In some embodiments, protocol stacks are implemented to enable communications between the client machine <b>10</b> and remote machines <b>30</b>.

0723<figref idref="DRAWINGS">FIG. 24</figref> is a flow diagram depicting one particular embodiment of a method for establishing an extensible and dynamically bindable protocol stack <b>20</b>. In one embodiment, the method allows a client machine <b>10</b> to specify the contents of a protocol stack dynamically without requiring that a remote machine <b>30</b> have a prior protocol stack description for a particular client machine and a particular application requirement.

0724In one embodiment, a remote machine <b>30</b> is on-line and monitoring activity on a specific transport system (e.g. LAN or WAN) and has initialized its protocol stack with the minimal necessary protocol modules to support a “TTY” communication mode. This mode is a raw ASCII stream mode with no protocol assumptions above the transport layer (i.e. there are no protocol layers for compression, encryption, reliability, framing, or modem). Similarly, a client machine <b>10</b> seeking access to the remote machine <b>30</b> establishes a connection to the common transport system with the minimum protocol set needed to support a TTY communication mode.

0725Upon detecting that a client machine <b>10</b> has established transport system connection (step <b>2401</b>), the application server broadcasts a TTY data stream, “DETECT.sub.—STRING”, in step <b>2402</b> that indicates service is available. The method used for detecting a client machine connection is transport system dependent (e.g. in the case of the TCP transport, when a client machine connects to a known port). If the client machine <b>10</b> does not respond within a prescribed time period, step <b>2403</b>, a re-broadcast of mission of the message occurs in step <b>2402</b>. Otherwise the process proceeds to step <b>2405</b> where the client machine <b>10</b> sends the TTY string “DETECT-STRING”. In step <b>2406</b>, the client machine <b>10</b> waits for the remote machine <b>30</b> to respond and, if the response is within a prescribed time interval, the process proceeds to steps <b>2407</b> where the client machine <b>10</b> enables the required protocol for supporting its application. Otherwise, the client machine <b>10</b> repeats the transmission of the message in step <b>2405</b>. The server responds in step <b>4108</b> by enabling the required set of protocols. At step <b>2409</b>, the TTY mode of communication ends because the next message sent by the server is a presentation layer protocol packet, “PACKET.sub.—INIT.sub.—REQUEST”, which indicates that the client's required “DETECT.sub.—STRING” has been received and accepted. In response to step <b>2409</b>, the client, at step <b>2410</b>, sends a set of presentation layer protocol packets, “PACKET.sub.—INIT.sub.—RESPONSE”, each of which is used to specify a required or optional protocol module that is being negotiated with the server. At step <b>2411</b>, the server sends a set of “PACKET.sub.—INIT.sub.—CONNECT” packets. The number of packets is variable: one for each client packet sent in step <b>2410</b>, thus giving the remote machine <b>30</b> the opportunity to negotiate the parameters under which communications will take place by overriding the parameters of the client machine <b>10</b>; or, the remote machine <b>30</b> may indicate that all of the parameters of the client machine <b>10</b> are acceptable by sending the parameters unchanged. At step <b>2412</b> the remote machine <b>30</b> enables the negotiated protocols (including any optional protocols) of step <b>2411</b>. After the client machine <b>10</b> receives the packets from step <b>2411</b>, the client machine <b>10</b> enables the negotiated protocols in step <b>2413</b>.

0726Still referring to <figref idref="DRAWINGS">FIG. 24</figref>, in some embodiments, a virtual machine host server communicates with the client machine <b>10</b> to enable negotiated protocols. As described above, a request is received from a client machine <b>10</b> for access to a computing environment or for application execution, the request including an identification of a user of the client machine <b>10</b>. In some embodiments, a virtual machine is launched in communication with a hypervisor. In other embodiments, a virtual machine host server is initialized with a prescribed set of protocols and associated protocol parameters providing a common transport mechanism, wherein the common transport mechanism is for raw ASCII stream mode communications. In still other embodiments, a virtual machine host server is initialized with a prescribed set of protocols and associated protocol parameters providing a common transport mechanism.

0727A virtual machine host server creates a first portion of a protocol stack. In one embodiment, a hypervisor creates the first portion of the protocol stack. In another embodiment, the hypervisor transmits a request protocol message to the client machine <b>10</b>. In still another embodiment, the hypervisor receives from the client machine <b>10</b> a plurality of protocol packets specifying one or more protocol parameters desired by the client machine <b>10</b>. In yet another embodiment, the virtual machine host server generates, in response to each received protocol packet, a packet counter-specifying one or more protocol parameters.

0728The virtual machine host server transmits a request protocol message to the client machine <b>10</b>. The virtual machine host server receives from the client machine <b>10</b> a plurality of protocol packets specifying one or more protocol parameters desired by the client machine <b>10</b>. The virtual machine host server transmits, in response to each received protocol packet, a packet counter-specifying one or more protocol parameters. In one embodiment, the virtual machine host server sends an acknowledgment message to the client machine <b>10</b> indicating that at least one of the protocols specified by the client machine <b>10</b> has been enabled. In another embodiment, the virtual machine host server responds to each received protocol packet transmitted by the client machine <b>10</b> with a virtual machine host server protocol packet, at least one of the virtual machine host server protocol packets modifying at least one of the associated protocol parameters. The virtual machine host server creates on the virtual machine host server a second portion of a protocol stack, the first portion and the second portion of the protocol stack establishing a communication channel for communicating with the client machine <b>10</b> having the negotiated protocol parameters.

0729Still referring to <figref idref="DRAWINGS">FIG. 24</figref>, in some embodiments, a virtual machine communicates with the client machine <b>10</b> to enable negotiated protocols as described above. As described above, a request is received from a client machine <b>10</b> for access to a computing environment or for application execution, the request including an identification of a user of the client machine <b>10</b>. A virtual machine in communication with a hypervisor is identified. In one embodiment, a virtual machine is launched in communication with a hypervisor. In another embodiment, a virtual machine in communication with a hypervisor is allocated. In one embodiment, a second virtual machine is initialized with a prescribed set of protocols and associated protocol parameters providing a common transport mechanism. In another embodiment, the second virtual machine is initialized with a prescribed set of protocols and associated protocol parameters providing a common transport mechanism, wherein the common transport mechanism is for raw ASCII stream mode communications.

0730The second virtual machine creates a first portion of a protocol stack. The second virtual machine transmits a request protocol message to the client machine <b>10</b>. The second virtual machine receives from the client machine <b>10</b> a plurality of protocol packets specifying one or more protocol parameters desired by the client machine <b>10</b>. The second virtual machine transmits, in response to each received protocol packet, a packet counter-specifying one or more protocol parameters. In one embodiment, the second virtual machine sends an acknowledgement message to the client machine <b>10</b> indicating that at least one of the protocols specified by the client machine <b>10</b> has been enabled. In another embodiment, the second virtual machine responds to each received protocol packet transmitted by the client machine <b>10</b> with a response protocol packet, at least one of the response protocol packets modifying at least one of the associated protocol parameters. The first virtual machine creates a second portion of a protocol stack, the first portion and the second portion of the protocol stack establishing a communication channel for communicating with the client machine <b>10</b> having the negotiated protocol parameters. In one embodiment, the first virtual machine sends an acknowledgment message to the client machine <b>10</b> indicating that at least one of the protocols specified by the client machine <b>10</b> has been enabled. In another embodiment, the first virtual machine responds to each received protocol packet transmitted by the client machine <b>10</b> with a response protocol packet, at least one of the response protocol packets modifying at least one of the associated protocol parameters.

0731Still referring to <figref idref="DRAWINGS">FIG. 24</figref>, in some embodiments, a virtual machine host server communicates with the client machine <b>10</b> to enable negotiated protocols as described above. As described above, a request is received from a client machine <b>10</b> for access to a computing environment or for application execution, the request including an identification of a user of the client machine <b>10</b>. In one embodiment, a virtual machine is launched in communication with a hypervisor. In another embodiment, a virtual machine in communication with a hypervisor is allocated. In one embodiment, the virtual machine host server is initialized with a prescribed set of protocols and associated protocol parameters providing a common transport mechanism. In another embodiment, the virtual machine host server is initialized with a prescribed set of protocols and associated protocol parameters providing a common transport mechanism, wherein the common transport mechanism is for raw ASCII stream mode communications.

0732The virtual machine host server transmits a request protocol message to the client machine <b>10</b>. The virtual machine host server receives from the client machine <b>10</b> a plurality of protocol packets specifying one or more protocol parameters desired by the client machine <b>10</b>. The virtual machine host server transmits, in response to each received protocol packet, a packet counter-specifying one or more protocol parameters. In one embodiment, the virtual machine host server sends an acknowledgement message to the client machine <b>10</b> indicating that at least one of the protocols specified by the client machine <b>10</b> has been enabled. In another embodiment, the virtual machine host server responds to each received protocol packet transmitted by the client machine <b>10</b> with a virtual machine host server protocol packet, at least one of the virtual machine host server protocol packets modifying at least one of the associated protocol parameters. The virtual machine host server generates a data structure representing the connection and associated with an initial protocol stack. The virtual machine host server identifies a virtual machine in communication with a hypervisor and generates a client space in the identified virtual machine. The virtual machine host server generates a second protocol stack associated with the generated client space and transfers the established connection between the virtual machine host server and the client machine <b>10</b> from the initial protocol stack to the second protocol stack by associating the data structure with the second protocol stack.

0733Still referring to <figref idref="DRAWINGS">FIG. 24</figref>, in some embodiments, a virtual machine communicates with the client machine <b>10</b> to enable negotiated protocols as described above. As described above, a request is received from a client machine <b>10</b> for access to a computing environment or for application execution, the request including an identification of a user of the client machine <b>10</b>. A first virtual machine in communication with a hypervisor is identified. In one embodiment, a second virtual machine is initialized with a prescribed set of protocols and associated protocol parameters providing a common transport mechanism. In another embodiment, a second virtual machine is initialized with a prescribed set of protocols and associated protocol parameters providing a common transport mechanism, wherein the common transport mechanism is for raw ASCII stream mode communications.

0734The second virtual machine transmits a request protocol message to the client machine <b>10</b>. The second virtual machine receives from the client machine <b>10</b> a plurality of protocol packets specifying one or more protocol parameters desired by the client machine <b>10</b>. The second virtual machine transmits, in response to each received protocol packet, a packet counter-specifying one or more protocol parameters. In one embodiment, the second virtual machine sends an acknowledgement message to the client machine <b>10</b> indicating that at least one of the protocols specified by the client machine <b>10</b> has been enabled. In another embodiment, the second virtual machine responds to each received protocol packet transmitted by the client machine <b>10</b> with a response protocol packet, at least one of the response protocol packets modifying at least one of the associated protocol parameters. The second virtual machine generates a data structure representing the connection and associated with an initial protocol stack. The second virtual machine generates a client space in the identified first virtual machine. The second virtual machine generates a second protocol stack associated with the generated client space and transfers the established connection between the second virtual machine and the client machine <b>10</b> from the initial protocol stack to the second protocol stack by associating the data structure with the second protocol stack.

0735Referring now to <figref idref="DRAWINGS">FIG. 25</figref>, a block diagram depicts one embodiment of a client machine <b>10</b> in communication with a remote machine <b>30</b>. When a client machine <b>10</b> wishes to access a resource provided by a remote machine <b>30</b>, the client machine <b>10</b> may transmit a request to the general communications port previously defined by the communications protocol or to the “well-known” communications port on the remote machine <b>30</b>. In one embodiment, the communication takes place by way of a datagram service. The remote machine <b>30</b> accesses the table of server addresses and returns a message containing the address of the remote machine <b>30</b>′ providing access to the requested resource and having the least load. In some embodiments, an address of a virtual machine executing on a remote machine <b>30</b>′ having the least load is provided. For embodiments in which the message identifies the execution machine having the lightest load, the operating system or hypervisor may forward the communication request, and all subsequent traffic, to the appropriate virtual machine.

0736Subsequent communications are automatically addressed by the client machine <b>10</b> also to a “well-known” or predefined general communications port on the remote machine <b>30</b>′. In one embodiment, the type of protocol with which the initial query was made to the remote machine <b>30</b> determines the protocol of the information returned by the remote machine <b>30</b> to the client machine <b>10</b>. Thus, if the request were made using a TCP/IP datagram, the remote machine <b>30</b> would return the TCP/IP address of the remote machine <b>30</b>′ to the client machine <b>10</b> and the client machine <b>10</b> would subsequently establish contact with the remote machine <b>30</b>′ using that protocol. In another embodiment, the datagram requesting an application address by a client machine <b>10</b> includes a request for a different type of protocol than the one used to send the request to the remote machine <b>30</b>. For example, the client machine <b>10</b> may make a request to the remote machine <b>30</b> using the IPX protocol and request the address of the remote machine <b>30</b>′ as a TCP/IP protocol address.

0737As described above, in connection with <figref idref="DRAWINGS">FIG. 8</figref>, (steps <b>802</b>-<b>804</b>), a remote machine <b>30</b> receives a request for access to a resource and chooses a method for providing access to the requested resource. In some embodiments, the remote machine <b>30</b> returns the network address of a remote machine <b>30</b>′ having the desired resource to the client machine <b>10</b>. The client machine <b>10</b> then uses the information received from the remote machine <b>30</b> to request connection to the specified remote machine <b>30</b>′. As is described above, such a connection is first established to a “well-known” communications port and is later transferred to a specific communications port under control of a connection manager. The specific communications port is associated with the resource executing on the remote machine <b>30</b>′ which then communicates with the client machine <b>10</b> through the specific communications port.

0738In more detail, and referring to <figref idref="DRAWINGS">FIG. 25</figref>, in some embodiments, a client process <b>2502</b> on client machine <b>10</b> makes a request <b>2504</b> to the remote machine <b>30</b> to obtain the address of a remote machine <b>30</b>′ which includes the desired resource <b>2506</b>. The remote machine <b>30</b> returns to the client machine <b>10</b> a message <b>2508</b> containing the address of the remote machine <b>30</b>′ which includes the resource <b>2506</b>. In one embodiment, the protocol used at this point of the connection is a datagram service.

0739The client machine <b>10</b> uses the returned address to establish a communication channel <b>2510</b> with the remote machine <b>30</b>′. The port number used by the client machine <b>10</b> corresponds to the “well-known port” in the remote machine <b>30</b>′ which has been defined by the network protocol as the port by which the remote machine <b>30</b>′ establishes communication connections with client machines <b>10</b>. The well-known port <b>2512</b> has a rudimentary protocol stack <b>2514</b> which includes primarily an endpoint data structure <b>2516</b>.

0740The endpoint data structure <b>2516</b> points to the communication protocol stack <b>76</b> and client connection thereby establishing a unique representation or “handle” for the client machine <b>10</b>. The endpoint data structure <b>2516</b> permits the connection between the remote machine <b>30</b>′ and the client machine <b>10</b> to be moved at will between the connection manager <b>2518</b> and the various resources <b>2506</b> on the machine <b>30</b>′. In some embodiments, the endpoint data structure <b>2516</b> permits the connection between the remote machine <b>30</b>′ and the client machine <b>10</b> to be moved at will to or from a virtual machine providing management functionality for a virtual machine on the remote machine <b>30</b>′.

0741The endpoint data structure <b>2516</b>, in one embodiment, not only contains the handle to the client machine <b>10</b> but may also contain other information relating to the client connection. In the embodiment shown, the machine <b>30</b>′ monitors activity on a specific communications system (e.g. LAN or WAN) and has initialized this minimum protocol stack <b>76</b> with only the necessary protocol modules needed to support a “TTY” communication mode. The “TTY” communication mode is a simple ASCII stream with no protocol assumptions above the transport layer. That is, there are no protocol layers for compression, encryption, reliability, framing, or presentation of transmitted data. Thus a client machine <b>10</b> seeking a resource <b>2506</b> running on the client machine <b>10</b>′ establishes a connection to the well-known communications port <b>2512</b> with the minimum protocol set needed to support a TTY communication mode.

0742A connection manager <b>2518</b> executing on the machine <b>30</b>′ is “listening” to the well-known communications port <b>2512</b> for a connection request <b>2510</b>. When a connection request <b>2510</b> is received from the client machine <b>10</b>, the connection manager <b>2518</b> is notified <b>2520</b>. The connection manager <b>2518</b> knows which protocol is being used based on the notification <b>2520</b>.

0743With this information the connection manager <b>2518</b> creates a new minimum protocol communications stack <b>2522</b>, starts a computing environment <b>2524</b> (referred to throughout this discussion as an execution environment <b>2524</b>) and binds the new minimum protocol stack <b>2522</b> to the execution environment <b>2524</b>. In some embodiments, the connection manager <b>2518</b> creates a new minimum protocol stack <b>2522</b> in a virtual machine on the remote machine <b>30</b>′. In other embodiments, the connection manager <b>2518</b> creates a new minimum protocol stack <b>2522</b> in a virtual machine providing administrative or management functionality for a virtual machine executing on the remote machine <b>30</b>′. In still other embodiments, the connection manager <b>2518</b> creates a plurality of minimum protocol stacks <b>2522</b>, each of which may be located on the remote machine <b>30</b>′, in a computing environment provided by a virtual machine executing on the remote machine <b>30</b>′, or on a virtual machine providing administrative or management functionality for a virtual machine executing on the remote machine <b>30</b>′.

0744In one embodiment, the remote machine <b>30</b>′ includes a number of execution environments <b>2524</b> which have been previously been started, but which have not been associated with a communications port. In this embodiment, the pre-connection starting of the execution environments permits a faster response time than if each execution environment <b>2524</b> is started when the connection request is received from the client machine <b>10</b>. When the execution environment <b>2524</b> is started, the resource <b>2506</b> requested by the client machine <b>10</b> is also started. In another embodiment, if the client machine <b>10</b> does not specify a resource, either a default application is started or the execution environment <b>2524</b> with no resource started. In some embodiments, the execution environment <b>2524</b> is the requested resource.

0745The connection manager <b>2518</b> then moves the client connection, including the unique client identifier or handle, from the well-known port <b>2512</b> to the new minimum protocol stack <b>2522</b>. In some embodiments, the connection manager <b>2518</b> moves the client connection to the new minimum protocol stack <b>2522</b> in a virtual machine on the remote machine <b>30</b>′. In other embodiments, the connection manager <b>2518</b> moves the client connection to the new minimum protocol stack <b>2522</b> in a virtual machine providing administrative or management functionality for a virtual machine executing on the remote machine <b>30</b>′. In still other embodiments, the connection manager <b>2518</b> moves portions of the client connection to a plurality of minimum protocol stacks <b>2522</b>, each of which may be located on the remote machine <b>30</b>′, in a computing environment provided by a virtual machine executing on the remote machine <b>30</b>′, or on a virtual machine providing administrative or management functionality for a virtual machine executing on the remote machine <b>30</b>′.

0746The connection manager <b>2518</b>, using the minimum protocol stack <b>2522</b> sends a TTY data stream that indicates service is available. Thus, this method for detecting a client connection is independent of the port to which the connection is first established. If the client machine <b>10</b> does not respond within a prescribed time period (e.g. 5 seconds) to the service available message, a resend of the “service available” message is performed by the machine <b>30</b>′.

0747If the client machine <b>10</b> receives the message, the client machine <b>10</b> sends a TTY string indicating that the “service available” message was detected. The client machine <b>10</b> waits for the machine <b>30</b>′ to respond and if the response is not within a prescribed time interval (e.g. 5 seconds) the client machine <b>10</b> resends the message. The connection manager <b>2518</b> then queries <b>90</b> the client machine <b>10</b> asking for the client's default communication parameters. This query <b>90</b> takes the form of a message which is passed back to the client machine <b>10</b> and which indicates that the client machine <b>10</b> should respond with details regarding what protocols the client machine <b>10</b> would like to use in the connection.

0748In response, the client machine <b>10</b> sends a set of protocol packets <b>2526</b>; each packet of which is used to specify a required or optional protocol module that is being requested from the remote machine <b>30</b>′. In one embodiment, the number of packets in the set is variable with one packet being sent for each protocol requested. In another embodiment, the number of packets that is being sent is included in the header of the first packet. In a third embodiment, the remaining number of packets being sent is included in the header of each packet and is decremented with each succeeding packet sent. Thus, the client machine <b>10</b> may respond to the query <b>2528</b> by indicating that, for example, encryption and data compression will be used. In such a case, two protocol packets will be sent from the machine client <b>10</b> to the remote machine <b>30</b>′ and, in one embodiment, the header of the first packet will indicate the number of packets as two.

0749Once the responses to the query <b>90</b> have been received, the connection manager <b>2518</b> builds a protocol stack using protocol drivers <b>2530</b>, <b>2530</b>′, <b>2530</b>″ which correspond to the protocols requested by the client machine <b>10</b>. In one embodiment, the connections manager <b>2518</b> places each of the required protocol drivers <b>2530</b>, <b>2530</b>′, <b>2530</b>″, corresponding to the requested client protocols (e.g. an encryption driver if encryption is desired by the client) into the protocol stack “container” <b>2532</b> and links them together. In some embodiments the connections manager <b>80</b> places protocol drivers <b>2530</b>, <b>2530</b>′, <b>2530</b>″ into a plurality of protocol stack “containers” <b>2532</b> residing in different locations and links the plurality of protocol stack “containers” <b>2532</b>. This dynamic process allows a client machine <b>10</b> to specify the contents of a protocol stack dynamically without requiring that the machine <b>30</b>′ have a prior protocol stack description for a particular client machine <b>10</b>. Using this method, multiple client machines <b>10</b> may be served by a single machine <b>30</b>, even if the separate client machines <b>10</b> have vastly differing requirements for the associated communications channel. In the embodiment shown, each client machine <b>10</b>, <b>10</b>′, <b>10</b>″ is associated with a respective communications protocol stack <b>2522</b>, <b>2522</b>′ and <b>2522</b>″. Such dynamically extensible protocol stacks are described in more detail below.

0750In the embodiment just discussed, the “container” <b>2532</b> is a user level or kernel level device driver, such as an NT device driver. This container driver provides ancillary support for the inner protocol modules or “drivers” (generally <b>2530</b>) which correspond to the protocol requirements of the client machine <b>10</b>. This ancillary support is in the form of helper routines that, for example, aid one protocol driver to transfer data to the next driver. Alternatively, in another embodiment each protocol driver is a complete user-level or kernel-level driver in itself.

0751Referring now to <figref idref="DRAWINGS">FIG. 26</figref>, the viewing user uses a so-called “browser” program to display an HTML page <b>2602</b> having a resource window <b>2604</b> on the screen <b>2606</b> of the user's client machine <b>10</b>. Once the viewing user has indicated that execution of the resource <b>2506</b> should commence, the browser application <b>2706</b> instantiates a parameter handler <b>2708</b> and passes the instantiation parameters associated with the resource window <b>2604</b> by the generic embedded window tag <b>2704</b>. The parameter handler <b>2708</b> instance spawns a network executive <b>2710</b> and passes to it the parameters of the resource window <b>2604</b>. The network executive <b>2710</b> determines which resource <b>2506</b> is to be invoked, and on what machine <b>30</b>′ that resource <b>2506</b> resides. Generally this information is passed to it by the parameter handler <b>2708</b> instance which gets it from the browser application <b>2706</b> in the form of the generic embedded window tag <b>2704</b>, but the network executive <b>2710</b> may need to query another remote machine <b>30</b>, in order to determine which servers, if any, host the desired resource <b>2506</b>. The network executive <b>2710</b> then begins execution of the resource and displays the output of the resource <b>2506</b> in the resource window <b>2604</b> as described in detail above.

0752The network executive <b>2710</b> continues to directly display resource output in the resource output window <b>2604</b>′ until the viewing user indicates that execution of the resource <b>2506</b> should stop, e.g. by closing the resource window <b>2604</b>, or until the viewing user clicks on a tag indicating that a different HTML page should be displayed. When this occurs, execution of the resource <b>2506</b> can be terminated. It is preferred, however, is to “cache” the connection. In effect, the first parameter handler <b>2708</b> instance is not immediately terminated. However, the resource <b>2506</b> continues executing with a reduced priority level, i.e. in “background” mode, because the first parameter handler <b>2708</b> no longer has “focus”.

0753In general, it is desirable to accomplish connection caching by providing the parameter handler <b>2708</b> source code with a globally accessible data structure for registering instances. For example, the parameter handler <b>2708</b> may be provided with a globally accessible linked list data structure, data array, data table, or other data structure. Because the data structure is globally available, each instance of the parameter handler <b>2708</b> is able to read and write the data structure. This allows each instance of the parameter handler <b>2708</b> to “register” with every other instance by writing to the data structure to signal its existence.

0754For embodiments in which no other connection information is stored, a predetermined limit on the number of connections that may be cached at any one time can be set. In these embodiments if registration of an instance would result in an excess number of cached connections, one of the “cached” connections is removed, i.e. the parameter handler <b>2708</b> instantiation associated with that connection is notified that it should terminate. Before termination, the parameter handler <b>2708</b> notifies its associated network executive <b>2710</b> that it should terminate. In turn, the network executive <b>2710</b> closes its session with the server hosting the resource <b>2506</b> and then terminates.

0755In embodiments in which other information is stored, the additional information may be used to more effectively manage the cached connections. For example, if a user has not actively viewed an HTML page <b>2602</b> in a predetermined number of minutes, e.g. ten minutes, the parameter handler <b>2708</b> instantiation is instructed to terminate, the session with the hosting server is terminated, and the parameter handler <b>2708</b> instance removes its entry in the registry.

0756Cached connection information may be managed using any known cache management scheme. Connection entries may be discarded on a “first in, first out” basis, i.e. the oldest entry is discarded each time a new entry must be added. Alternatively, cached connection information entries may be discarded on a “least recently used” basis, which discards information relating to connections which have been used the least amount by the user. Other cache management techniques, such as random replacement, may also be used.

0757If the viewing user returns to a previous HTML page <b>2602</b> having a cached connection, the network executive <b>2710</b> associated with the HTML page <b>2602</b> is returned to the foreground, i.e., it regains “focus”, and processing of the associated resource resumes at a normal priority level. If necessary, the network executive <b>2710</b> re-establishes the connection with the resource <b>2506</b>. Although no output data is stored by the network executive <b>2710</b> for cached connections, as soon as a connection is re-established for a resource window <b>2604</b> the connection to the resource <b>2506</b> is re-established and the resource <b>2506</b> again writes directly to the resource window <b>2604</b>.

0758Referring to <figref idref="DRAWINGS">FIG. 27</figref>, an HTML file <b>2602</b> located on a machine <b>30</b>′ and constructed in accordance with an embodiment of the invention includes a generic embedded window tag <b>2704</b>. The generic embedded window tag <b>2704</b> is any data construct which indicates to a browser <b>60</b> displaying the HTML file <b>2602</b> that a generic embedded window <b>2604</b> should be displayed at a particular location in the HTML page <b>2602</b> described by the HTML file <b>2602</b>. The generic embedded window tag <b>2704</b> may include additional information, such as height of the window, width of the window, border style of the window, background color or pattern in the window, which resources may be displayed in the window, how often the output display should be updated, or any other additional information that is useful to enhance display of the resource output.

0759Some examples of generic embedded window tags that can be embedded in an HTML file follow.

0000<tables id="TABLE-US-00007" num="00007"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="offset" colwidth="14pt" align="left" /><colspec colname="1" colwidth="203pt" align="left" /><thead><row><entry /><entry namest="offset" nameend="1" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>ActiveX tag</entry></row><row><entry /><entry> <object classid=“clsid:238f6f83-b8b4-11cf-8771-00a024541ee3”</entry></row><row><entry /><entry>  data=“/ica/direct.ica” CODEBASE=“/cab/wfica.cab”</entry></row><row><entry /><entry>  width=436 height=295></entry></row><row><entry /><entry>  <param name=“Start” value=“Auto”></entry></row><row><entry /><entry>  <param name=“Border” value=“On”></entry></row><row><entry /><entry> </object></entry></row><row><entry /><entry>Netscape Plugin tag</entry></row><row><entry /><entry> <embed src=“http://www.citrix.com/ica/direct.ica”</entry></row><row><entry /><entry>  pluginspage=“http://www.citrix.com/plugin.html”</entry></row><row><entry /><entry>  height=295 width=436 Start=Auto Border=On></entry></row><row><entry /><entry> <embed></entry></row><row><entry /><entry>JAVA tag</entry></row><row><entry /><entry> <applet code=JICA.class width=436 height=295></entry></row><row><entry /><entry>  <param name=Address value=“128.4.1.2602”></entry></row><row><entry /><entry>  <param name=InitialProgram value=Microsoft Word 7.0></entry></row><row><entry /><entry>  <param name=Start value=Auto></entry></row><row><entry /><entry>  <param name=Border value=On></entry></row><row><entry /><entry> </applet></entry></row><row><entry /><entry namest="offset" nameend="1" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0760In each case above, the tag indicates that a window having a height of 295 pixels and a width of 436 pixels should be drawn to receive resource output. Each tag also specifies that the resource should automatically start execution and that the window in which the resource output is displayed should be drawn with a border. The ActiveX and Netscape Plugin tags have the remote resource parameters specified in the file “direct.ica” located in the directory “/ica.” The JAVA tag specifies the remote resource parameters directly. In the example above, the address of the machine <b>30</b> hosting the resource is specified as well as the name of the resource to be executed.

0761The browser application <b>2706</b> accesses the HTML file <b>2602</b> by issuing a request to a specific Uniform Resource Locator (URL) address. The machine <b>30</b>′ hosting the HTML file <b>2602</b> transmits the HTML file <b>2602</b> data to the browser application <b>2706</b>, which displays text and translates any tags that are included in the HTML file <b>2602</b>. The browser application <b>2706</b> displays the HTML file <b>2602</b> data as an HTML page <b>2602</b>. If a generic embedded window tag <b>2704</b> is present in the HTML file <b>2602</b>, such as one of the tags described above, the browser <b>60</b> draws a blank window <b>2604</b> in the displayed HTML page <b>2602</b>.

0762Execution of the desired resource <b>2506</b> may commence immediately upon display of the HTML page <b>2602</b> or execution may await some signal, e.g. a specified user input which indicates execution of the resource <b>2506</b> should begin. Once execution of the resource <b>2506</b> is commenced, the browser application <b>2706</b> instantiates a parameter handler <b>2708</b> associated with the resource window <b>2604</b>. The parameter handler <b>2708</b> instance may be spawned as a child process of the browser application <b>2706</b>, as a peer process of the browser application <b>2706</b>, a statically-linked thread of execution, a dynamically-link thread of execution, or as a Dynamically Linked Library (“DLL”) associated with the browser application <b>2706</b>.

0763The browser application <b>2706</b> passes any specific parameters associated with the resource window <b>2604</b> that were provided by the generic embedded window <b>66</b> tag to the parameter handler <b>2708</b> instance. Additionally, the browser application <b>2706</b> may pass the handle for the resource window <b>2604</b> to the parameter handler <b>2708</b> instance or the parameter handler <b>2708</b> instance may query the browser application <b>2706</b> to retrieve the handle for the resource window <b>2604</b>. The parameter handler <b>2708</b> instance also spawns a network executive <b>2710</b>. The network executive <b>2710</b> may be spawned as a child process of the parameter handler <b>2708</b> instance, a statically-linked thread of execution, a dynamically-link thread of execution, or as a peer process of the parameter handler <b>2708</b> instance.

0764The parameter handler <b>2708</b> instance forwards any specified resource window <b>2604</b> parameters to the network executive <b>2710</b>. Parameters which are not specified by the parameter handler <b>2708</b> instance or the embedded generic window tag <b>2704</b> may be set to default values. The network executive <b>2710</b> may have certain parameter defaults hard-coded, or the network executive <b>2710</b> may access a file which contains parameter defaults.

0765The network executive <b>2710</b> creates its own resource output window <b>2604</b>′. The network executive <b>2710</b> creates its resource output window <b>2604</b>′ as a child of the displayed resource window <b>2604</b> and displays its resource output window <b>2604</b>′ directly over the parent window <b>2604</b> drawn by the browser application <b>2706</b>. Since the resource output window <b>2604</b>′ drawn by the network executive <b>2710</b> is a child of the resource window <b>2604</b> drawn by the browser application <b>2706</b>, the resource output window <b>2604</b>′ inherits various properties of its parent including position information. Accordingly, the resource output window <b>2604</b>′ will follow the resource window <b>2604</b> as the viewing user scrolls the screen of the browser application <b>2706</b> or performs other actions which vary the position of the resource window <b>2604</b>.

0766The network executive <b>2710</b> also establishes a communications channel with the machine <b>30</b>′ and invokes execution of the desired resource <b>2506</b> by the machine <b>30</b>′ using the connection methodology described above. The network executive <b>2710</b>, which acts as the client machine <b>10</b> in the above description, passes any parameters it received from the parameter handler <b>2708</b> instantiation to the machine <b>30</b>′, along with any necessary default values. If a parameter is not passed to the machine <b>30</b>′, the machine <b>30</b>′ may request the parameter if it is a necessary parameter which has no default value, e.g. “user id,” or it may provide a default value for the parameter, e.g. execution priority. The machine <b>30</b>′ begins execution of the desired resource <b>2506</b> and directs the output to the network executive <b>2710</b>. The network executive <b>2710</b> receives data from the resource <b>2506</b> and displays the output data in its resource output window <b>2604</b>′. Since the resource output window <b>2604</b>′ is drawn on top of the resource window <b>2604</b> drawn by the browser application <b>2706</b>, the resource output data is displayed in the HTML page <b>2602</b>. As noted above, the resource output window <b>2604</b>′ drawn by the network executive <b>2710</b> is a child of the resource window <b>2604</b> drawn by the browser application <b>2706</b>. This allows the resource output window <b>2604</b>′ to scroll as the HTML page <b>2602</b> is scrolled

0767The resource output window <b>2604</b>′ also receives input from the viewing user. Raw input data, e.g. a mouse click, is received into the resource output window <b>2604</b>′ by the network executive <b>2710</b>. The network executive <b>2710</b> forwards the raw input data to the resource <b>2506</b> executing on the machine <b>30</b>″ In this manner, the viewing user is able to interact with the resource <b>2506</b> via the HTML page <b>2602</b>.

0768Referring now to <figref idref="DRAWINGS">FIG. 28</figref>, and in brief overview, an embodiment of an interactive hypermedium system of the invention includes a client machine <b>10</b>, a network remote machine <b>30</b> and an execution remote machine <b>30</b>′ interconnected by a communications link <b>150</b>, herein referred to without any loss of generality as a network or web. The network remote machine <b>30</b> may be provided by a remote machine <b>30</b>. The execution machine <b>30</b>′ may be provided by a physical machine or a virtual machine.

0769A user on a client machine <b>10</b> wishing to access the resource <b>2802</b> which is located on the execution machine <b>30</b>′ on the web <b>150</b> does so through a graphical user interface <b>2804</b>, which is herein referred to without any loss of generality as a hypermedium, located on the client machine <b>10</b>. The graphical interface is displayed on a graphical display device <b>124</b>. Data is entered by a mouse <b>16</b> and a keyboard <b>17</b> located on the client machine <b>10</b>. The graphical display or page <b>2806</b> which the user first views on the hypermedium <b>2804</b> is referred to herein without any loss of generality as the home page or web page of the resource <b>2802</b>. A page <b>2806</b> or home page of the hypermedium <b>2804</b> includes a graphic link <b>2808</b> or textual link <b>2810</b> herein referred to without any loss of generality as a hyperlink. The web page is displayed by a process <b>2602</b> referred to herein without any loss of generality as a network browser <b>2602</b> executing on the client machine <b>10</b>.

0770The network browser <b>2602</b> obtains the first page or web page <b>2806</b> from a network remote machine <b>30</b> and displays the web page <b>2806</b> on the hypermedium <b>2804</b> for the user to view on the graphical display device <b>124</b>. When the user selects a resource <b>2802</b> to access (by selecting a graphical <b>2808</b> or textual <b>2810</b> hyperlink using the mouse <b>16</b> or keyboard <b>17</b>) the network browser <b>2602</b> obtains a network configuration file <b>2812</b> corresponding to the selected resource <b>2802</b> from a predetermined network server <b>2606</b> and starts a client agent <b>2814</b> which will communicate with the selected resource <b>2802</b>. This will be discussed in more detail below.

0771The client agent <b>2814</b> reads the configuration file <b>2812</b> and establishes a communications link to a server agent <b>2816</b> on the execution server <b>24</b> specified by the configuration file <b>2812</b>. In one embodiment, the configuration file <b>2812</b> includes the name of the resource and the node location of the resource <b>2802</b> corresponding to the hyperlink <b>2808</b>, <b>2810</b>. The configuration file may also contain optional information such as authentication or authorized user information. Server agent <b>2816</b> performs the operations necessary (such as authentication) to permit the client agent <b>2814</b> access to the resource <b>2802</b>, and once access is permitted, allows access to the resource <b>2802</b> requested by the user. The server agent <b>2816</b> may execute in a hypervisor, a virtual machine, or on an operating system. In some embodiments, the functionality provided by the server agent <b>2816</b> is split between a hypervisor and a virtual machine or between two virtual machines. In still other embodiments, the functionality provided by the server agent is split between a hypervisor and a guest operating system executing in a virtual machine. In some embodiments, a connection to a computing environment including the resource <b>2802</b> is established, as described in further detail below.

0772Once the resource <b>2802</b> is available on the execution server <b>30</b>′, the client machine <b>10</b> may access the resource <b>2802</b> through the server agent <b>2816</b> directly with the client agent <b>2814</b> without intervention by the network browser <b>2602</b>. The client agent <b>2814</b> is then responsible for receiving data from the user through the mouse <b>16</b> and keyboard <b>17</b> and transmitting it to the resource <b>2802</b> on the execution machine <b>30</b>′. Similarly, the client agent <b>2814</b> is responsible for receiving data from the resource <b>2802</b> on the execution machine <b>30</b>′ and displaying the data in a display window <b>2818</b> on the graphical display device <b>124</b> on the client machine <b>10</b>. It should be noted that the display window <b>2818</b> may be located within the boundaries or outside the boundaries of the hypermedium <b>2804</b>. When the resource <b>2802</b> is completed the server agent <b>2816</b> instructs the client agent <b>2814</b> to disconnect the communication link <b>150</b> between the client agent <b>2814</b> and the server agent <b>2816</b>. In some embodiments, the server agent <b>2816</b> may reside outside of the execution machine <b>30</b>′. In other embodiments, the client agent <b>2814</b> may reside outside of the client machine <b>10</b>.

0773<figref idref="DRAWINGS">FIG. 29</figref> depicts the operation of the system in more detail. Initially, the client agent <b>2814</b> is registered (step <b>2901</b>) with the network browser <b>2602</b> of the client machine <b>10</b> and an entry is made in the network browser's registration file <b>2820</b> (<figref idref="DRAWINGS">FIG. 28</figref>). This entry permits the network browser <b>2602</b> to start the client agent <b>2814</b> whenever a given file type (including types such as a MIME type) is requested by the hyperlink <b>2808</b>, <b>2810</b> of the hypermedium <b>2804</b>. In this case the client agent <b>2814</b> is designed to permit a user on the client machine <b>10</b> to execute and interact with a remote resource <b>2802</b> on an execution machine <b>30</b>′. The client agent <b>2814</b> would be registered with the network browser <b>2602</b> such that whenever a hyperlink <b>2808</b>, <b>2810</b> requested the given file type (for example .RMT for remote execution) from the network browser <b>2602</b>, the network browser <b>2602</b> would start the client agent <b>2814</b> which would permit remote execution and interaction with a resource <b>2802</b> resident on an execution machine <b>30</b>′. The invoking of the client agent <b>2814</b> is discussed in more detail below.

0774When a user wishes to access a resource from a hypermedium environment, for example a database program, the hypermedium <b>2804</b> is displayed in a manner that is well known to those skilled in the art. When the user selects a hyperlink <b>2808</b>, <b>2810</b> on the page <b>2806</b> of the hypermedium (step <b>2902</b>) by using the mouse <b>16</b> or keyboard <b>17</b> on the client machine <b>10</b>, a request is made to the network browser <b>2602</b> for the corresponding data file (step <b>2903</b>). In this example, the file type (.RMT) is requested.

0775The network browser <b>2602</b> obtains the corresponding configuration file <b>2812</b> from the network server <b>2606</b> which is specified in the file request made by the hyperlink <b>2808</b>, <b>2810</b> to the network browser <b>2602</b> (step <b>2904</b>). The network browser <b>2602</b> then compares the obtained configuration file <b>2812</b> with the registration file <b>2820</b> of client agent names which it maintains (step <b>2905</b>). In one embodiment, the network browser <b>2602</b> compares a file type of the obtained configuration file <b>2812</b> with the registration file <b>2820</b>. In another embodiment, the network browser <b>2602</b> compares an entry in the obtained configuration file <b>2802</b> with the registration file <b>2820</b>. If the client agent <b>2814</b> specified by the configuration file <b>2812</b> is found in the registration file <b>2820</b>, the client agent <b>2814</b> is started (step <b>2906</b>).

0776The invoked client agent <b>2814</b> reads the configuration file <b>2812</b> (step <b>2907</b>), and based upon the information in the configuration file <b>2812</b>, begins to establish a communication link with the server agent <b>2816</b> on the execution server <b>24</b> (step <b>2908</b>), in this case the sales database application execution server (generally <b>30</b>′).

0777Considering the process of beginning the communications link of step <b>2908</b> (<figref idref="DRAWINGS">FIG. 29</figref>) in more detail, communication begins with the server agent <b>2816</b> monitoring communication activity on the network <b>150</b>. At this point, no protocol assumptions are made by the server agent <b>2816</b> beyond those necessary for the transport layer. Similarly, the client agent <b>2814</b> also makes no assumption of the communications protocol beyond that required by the transport layer. Once the server agent <b>2816</b> determines that a client agent <b>2814</b> is attempting to communicate with it, the server agent <b>2816</b> transmits a message to the client agent <b>2814</b> indicating that service is available.

0778Once the client agent <b>2814</b> determines that service is available on the execution remote machine <b>30</b>′, the client agent <b>2814</b> transmits a message to the server agent <b>2816</b> indicating that it is ready to proceed with the communication protocol. Once the server agent <b>2816</b> has responded that it is ready to continue the communication protocol, the client agent <b>2814</b> enables the protocol necessary for it to run the application <b>36</b>. In response to the message from the client agent <b>2814</b>, the server agent <b>2816</b> also enables the required protocol. The server agent <b>2816</b> then transmits a message using the required protocol indicating that the client agent's request has been received and accepted.

0779In response the client agent <b>2814</b> and the server agent <b>2816</b> exchange a set of messages which negotiate the parameters under which communications will occur. Once negotiations are complete, the client agent <b>2814</b> and the server agent <b>2816</b> are able to communicate as necessary for the resource <b>2802</b> to be run by the user.

0780Once the communications protocol has been established and the server agent <b>2816</b> has authenticated the client agent <b>2814</b> (step <b>2909</b>) (for example determining that the user has permission to read and write to the database) access to the resource <b>2802</b> (step <b>2910</b>) is provided by the application execution server <b>24</b>. At this point resource <b>2802</b> on the execution server <b>30</b>′ is communicating via the server agent <b>2816</b> with the client agent <b>2814</b> on the client machine <b>10</b>. The client agent <b>2814</b> is now responsible for transmitting data input by the user using the mouse <b>16</b> and keyboard <b>17</b> to the resource <b>2802</b> on the execution machine <b>30</b>′. Further, the client agent <b>2814</b> is responsible for receiving data for display from the resource <b>2802</b> and displaying that data in the application window <b>2818</b> on the graphical display device <b>124</b> of the client machine <b>10</b>.

0781It should be noted that the underlying presentation protocol which passes data to a transport layer such as TCP/IP must be capable of transferring graphical information. Examples of such protocols which may be used for interactive hypermedia communication include public domain X11 protocol, the proprietary Independent Computing Architecture (ICA) protocol of Citrix Systems Inc., or the proprietary Remote Desktop Protocol (RDP) of Microsoft Corporation.

0782Thus the above described system permits a user on a client machine <b>10</b>, which may have very limited resources, to start and interact with a resource <b>2802</b> located on an execution machine <b>30</b>′. The resource <b>2802</b> then runs on the execution machine <b>30</b>′ and the data is input and the results displayed on the client machine <b>10</b>. In some embodiments, the accessed resource <b>2802</b> executes in a virtual machine provided by the remote machine <b>30</b>′.

0783Referring now to <figref idref="DRAWINGS">FIG. 30</figref>, a flow diagram depicts an embodiment of method of making a hypermedium page interactive, the hypermedium page displayed by a network browser. As described above, a hyperlink on a hypermedium page displayed on a client machine <b>10</b> is selected, the hyperlink identifying a desired computing resource (step <b>3002</b>). A hyperlink configuration file is retrieved, the hyperlink configuration file corresponding to the hyperlink and identifying a remote machine <b>30</b>′ (step <b>3004</b>). A client agent is started on a client machine <b>10</b> (step <b>3006</b>). The client agent creates a communication link to a virtual machine executing on the remote machine <b>30</b>′ identified by the hyperlink configuration file (step <b>3008</b>). The client agent receives data from the virtual machine and displays on the client machine <b>10</b> the received data without intervention by the network browser (step <b>3010</b>).

0784A hyperlink on a hypermedium page displayed on a client machine <b>10</b> is selected, the hyperlink identifying a desired computing resource (step <b>3002</b>). In one embodiment, the hypermedium page is obtained from a remote machine <b>30</b> prior to selection of the hyperlink on the hypermedium page. In another embodiment, the hypermedium page is received responsive to a request for an enumeration of available resources.

0785A hyperlink configuration file is retrieved, the hyperlink configuration file corresponding to the hyperlink and identifying a remote machine <b>30</b>′ (step <b>3004</b>). In one embodiment, a remote machine <b>30</b>, functioning as a brokering machine, identifies the remote machine <b>30</b>′. In another embodiment, the remote machine <b>30</b>′ functions as an execution machine. In still another embodiment, a hypervisor executes on the remote machine <b>30</b>′. In yet another embodiment, a virtual machine is launched into a hypervisor executing on the remote machine <b>30</b>. In some embodiments, a server agent starts on a virtual machine in the remote machine <b>30</b>′.

0786A client agent is started on the client machine <b>10</b> (step <b>3006</b>). In one embodiment, the client agent is started by the network browser upon a successful match of an entry in the hyperlink configuration file with an identifier associated with the client agent in a registration file accessible by the network browser. In another embodiment, the client agent is registered with the network browser.

0787The client agent creates a communication link to a virtual machine executing on the remote machine <b>30</b>′ identified by the hyperlink configuration file (step <b>3008</b>). In one embodiment, execution of an identified application program begins on the virtual machine in response to the created communication link. In another embodiment, the client agent creates the communication link without intervention by the network browser.

0788The client agent receives data from the virtual machine and displays on the client machine <b>10</b> the received data without intervention by the network browser (step <b>3010</b>). In one embodiment, the data received from the virtual machine is displayed in a display window on the client machine <b>10</b>. In some embodiments, a presentation layer protocol is employed for communication over the communication link.

0789Referring back to <figref idref="DRAWINGS">FIG. 28</figref>, in some embodiments of a system for making a hypermedium page interactive, access to a requested computing environment is provided through the interactive hypermedium page. The client machine <b>10</b> executes a browser application <b>2602</b>. A remote machine <b>30</b> functions as a network server <b>2606</b> and transmits a network configuration file to the client machine <b>10</b>. A client agent <b>2814</b> executing on the client machine <b>10</b> establishes a communications link with a remote machine <b>30</b>′, functioning as an execution machine <b>30</b>′.

0790As described above, the client machine <b>10</b> executes a browser application <b>2602</b>, which displays a hypermedium page including a hyperlink identifying a resource <b>2802</b>. A remote machine <b>30</b> functions as a network server <b>30</b> and transmits, in response to selection of said hyperlink, a network configuration file to the client machine <b>10</b>, the network configuration file corresponding to said identified computing resource <b>2802</b>. In some embodiments, a process obtains the hypermedium page from the network server <b>30</b> and provides the hypermedium page to the client machine <b>10</b>.

0791In one embodiment, the network configuration file comprises a resource identifier corresponding to said hyperlink and a virtual machine address corresponding to said hyperlink. In some embodiments, the virtual machine address is a virtual IP address provided by a hyperlink in which the virtual machine executes. In other embodiments, the virtual machine address is an IP address associated with an execution machine <b>30</b>′ on which the virtual machine executes.

0792A client agent <b>2814</b> executing on the client machine <b>10</b> establishes a communications link with a remote machine <b>30</b>′, functioning as an execution machine <b>30</b>′. The client agent <b>2814</b> establishes the link responsive to data in the network configuration file. In one embodiment, a hypervisor executes on the execution machine <b>30</b>′ and a virtual machine providing the resource <b>2802</b> executes in the hypervisor. In some embodiments, the virtual machine transmits data to the client agent <b>2814</b> for display without intervention by the browser application <b>2602</b>. In one of these embodiments, the virtual machine provides access to the requested resource <b>2802</b> and the data is output from an execution of the requested resource <b>2802</b>.

0793In some embodiments, the client agent establishes, responsive to data in the configuration file, a communications link with a management program executing on a remote machine. In one of these embodiments, the management program executes on the network server <b>2606</b>. In another of these embodiments, the management program executes on the execution machine <b>30</b>′. In still another of these embodiments, the management program executes on a virtual machine in the execution machine <b>30</b>′. In yet another of these embodiments, the management program executes on a virtual machine having management privileges on the execution machine <b>30</b>′ or on a remote machine <b>30</b>″. In other embodiments, the management program launches the virtual machine providing the desired computing resource into a hyperlink on the execution machine <b>30</b>′.

0794In some embodiments, the client agent <b>2814</b> displays data received from said virtual machine in a display window located at the client machine <b>10</b>. In one of these embodiments, the display window is located within the boundaries of the hypermedium page. In another of these embodiments, the display window is located outside the boundaries of the hypermedium page.

0795Referring to <figref idref="DRAWINGS">FIG. 31</figref>, in some embodiments of the methods described above, data transmitted by the resource <b>2506</b> is sent to other remote machines <b>30</b> prior to being sent to client machines <b>10</b>. In this manner, data transmitted by the resource <b>2506</b> is transmitted to an increasing number of client machines <b>10</b> as the network fans out.

0796When each client machine <b>10</b> terminates its connection with the machine <b>30</b>′, each client protocol stack (generally <b>2522</b>) and its associated minimal stack (generally <b>3102</b>) is destroyed. Similarly, the minimal protocol stack (generally <b>3104</b>) associated with the first client protocol stack <b>2522</b> is also destroyed. When the last of the minimal <b>3102</b> and second (and subsequent) client protocol stacks <b>2522</b> has terminated, the configuration is as it was initially with only a first client communications protocol stack <b>2522</b> associated with the execution environment <b>2524</b>. Note that until all the second and subsequent client protocol stacks <b>2522</b> are terminated, the first client protocol stack <b>2522</b> may not be destroyed, even if the client machine <b>10</b> is no longer present.

0797As shown in <figref idref="DRAWINGS">FIG. 25</figref> above, each execution environment <b>2524</b> communicates with each protocol stack <b>2522</b> through a multiplexer <b>2534</b>, <b>2534</b>′, <b>2534</b>″. Now referring also to <figref idref="DRAWINGS">FIG. 31</figref>, it is possible for more than one machine <b>10</b> to receive data being transmitted to the client machine <b>10</b>, for example, in order to shadow or monitor the transmission of data from a machine <b>30</b>′ or to broadcast data from a specialized broadcast application, such as a stock quotation application, from which the same data is broadcast or transmitted substantially simultaneously to a number of clients (generally <b>10</b>).

0798In such a case, the client machine <b>10</b> causes the specialized resource <b>2506</b> to execute and transmit its data to the client machine <b>10</b> as discussed previously. When a client machine <b>10</b>′ requests access to the broadcast resource <b>2506</b>, the connection manager <b>2518</b> begins to construct the protocol stack <b>2522</b>′ for the second client machine <b>10</b>′ as previously discussed with regard to the first client machine <b>10</b>. However, because the resource <b>2506</b> is a broadcast application, the connection manager <b>2518</b> recognizes that it need not start an additional execution environment <b>2524</b> and instead takes the steps necessary to send the data from the broadcast resource <b>2506</b> to the client machine <b>10</b> and any additional machine <b>10</b>″.

0799First, the connection manager <b>2518</b> creates a first minimal communications protocol stack <b>3104</b> which it associates with a communications protocol stack <b>2522</b> of the first client machine <b>10</b>. The connection manager <b>2518</b> next creates a second minimal protocol stack <b>3102</b> and associates it with the communications protocol stack <b>2522</b>′ of the second client machine <b>10</b>′. As each additional client machine <b>10</b>″ requests access to the broadcast resource <b>2506</b>, another minimal protocol stack <b>3104</b>′ is created and associated with the first client protocol stack <b>2522</b> and another minimal protocol stack <b>3102</b>′ and client protocol stack <b>2522</b>″ is created for each new client machine <b>10</b>″. The first client protocol stack <b>2522</b> and all the minimal protocol stacks <b>3104</b>, <b>3104</b>′ associated with the first client protocol stack <b>2522</b>, and each pair of client protocol stacks <b>2522</b>′, <b>2522</b>″ and minimal protocol stacks <b>3102</b>, <b>3102</b>′ associated with each additional machine <b>10</b>′, <b>10</b>″ are in communication by way of a multiplexer <b>2534</b>.

0800In some embodiments, the connection manager <b>2518</b> resides outside of a virtual machine executing on a remote machine <b>30</b>′ and creates minimal protocol stacks <b>3102</b> within the virtual machine executing on the remote machine <b>30</b>′. In other embodiments, the connection manager <b>2518</b> resides outside of a virtual machine executing on a remote machine <b>30</b>′ and creates minimal protocol stacks <b>3102</b> within a second virtual machine providing management and administrative functionality for the virtual machine executing on the remote machine <b>30</b>′. In still other embodiments, the connection manager <b>2518</b> resides outside of a virtual machine executing on a remote machine <b>30</b>′ and creates minimal protocol stacks <b>3102</b> within a hypervisor providing management and administrative functionality for the virtual machine executing on the remote machine <b>30</b>′. In yet other embodiments, the connection manager <b>2518</b> resides outside of a virtual machine executing on a remote machine <b>30</b>′ and creates minimal protocol stacks <b>3102</b> within a host operating system on the remote machine <b>30</b>′ providing management and administrative functionality for the virtual machine executing on the remote machine <b>30</b>′. In some embodiments, the connection manager <b>2518</b> resides inside a virtual machine executing on a remote machine <b>30</b>′ and creates minimal protocol stacks <b>3102</b> within the virtual machine executing on the remote machine <b>30</b>′.

0801When a multiplexer <b>2534</b> is directing data to or receiving data from only one machine <b>10</b>, the multiplexer <b>2534</b> is acting as a simple pass-through device. However, when there is more than one client machine <b>10</b>, <b>10</b>′, <b>10</b>″ receiving data from or transmitting data to a single resource <b>2506</b>, each multiplexer (generally <b>2534</b>) takes on two additional configurations. In one configuration, the multiplexer <b>2534</b> is configured to send resource data to or receive data from both the first client protocol stack <b>2522</b> and each of the minimal communications protocol stacks <b>3104</b>, <b>3104</b>′ associated with it. In the second configuration the multiplexer <b>2534</b> is configured to send data received by the minimal protocol stack <b>3102</b>, <b>3102</b>′ to the client protocol stack <b>2522</b>′, <b>2522</b>″, respectively, associated with it. In this embodiment, the multiplexer <b>2534</b> may receive input data directly from each client protocol stack <b>2522</b>, <b>2522</b>′, <b>2522</b>″.

0802The connection manager <b>2518</b> connects the minimal protocol stacks <b>3104</b>, <b>3104</b>′ associated with the client machine <b>10</b> with the minimal protocol stacks <b>3102</b>, <b>3102</b>′ respectively, of the second client machine <b>10</b>′ and subsequent client machines <b>10</b>″ and instructs the multiplexer <b>2534</b> to direct output from the resource <b>2506</b> to the communications protocol stack <b>2522</b> of the client machine <b>10</b> and its associated minimal protocol stacks <b>3104</b>, <b>3104</b>′. The multiplexer <b>2534</b> is also instructed by the connection manager <b>2518</b> to connect each second and subsequent client minimal protocol stack <b>3102</b>, <b>3102</b>′ to its associated client protocol stack <b>2522</b>, <b>2522</b>′, respectively. Data transmitted to the client machine <b>10</b> by way of the first client protocol stack <b>2522</b> is therefore also transmitted to the minimal protocol stacks <b>3104</b>, <b>3104</b>′ associated with the client machine <b>10</b> and hence to the client machine <b>10</b>′ and subsequent client machines <b>10</b>″ by way of their associated protocol stacks <b>2522</b>′, <b>2522</b>″, respectively, and associated minimal protocol stacks <b>3102</b>, <b>3102</b>′, respectively. In one embodiment, the protocol stack container includes a data structure to keep track of the number and type of protocols associated with a given resource <b>2506</b>.

0803Referring to <figref idref="DRAWINGS">FIG. 32</figref>, as discussed above, it is possible that the “clients” of one machine <b>30</b>′ be other remote machines <b>30</b>′ and <b>30</b>″ (only two being shown for simplicity). The remote machines <b>30</b>′ and <b>30</b>″ then transmit the data to client machines <b>10</b> or to additional remote machines <b>30</b>′. In this embodiment the output of the server protocol stack (generally <b>2522</b>) is connected to the protocol stacks <b>107</b>′ of the secondary remote machines <b>30</b>′ and <b>30</b>″. Then as described previously, the data is transmitted between the protocol stacks and out to the client machines <b>10</b>. In this manner the data may fan out and be distributed to many more clients than may reasonably be supported by one server. In some embodiments, the output of the server protocol stack may be connected to protocol stacks <b>3102</b>′ created in virtual machines executing on remote machines <b>30</b>.

0804In brief overview, in one embodiment of the methods described above, a user of a client machine <b>10</b> requests access to one or more resources from a remote machine <b>30</b>, which may provide web server functionality. After authenticating the user's credentials, the web server accesses user-specific and resource-specific parameters from a memory coupled to the web server. The web server subsequently communicates these parameters to one or more remote machines <b>30</b> hosting the requested resources, and software processes operating on the resource servers execute and initialize the requested resources using the communicated parameters. In this manner, each instance of the resources is personalized for a particular requesting user. The particular network addresses of the resource servers hosting these personalized application programs are then forwarded to the user's client machine <b>10</b>, which establishes a communications link and client-server session therewith.

0805Commands, events, graphical data, and window attribute information associated with the executing resources are communicated between the user device and the resource servers during the client-server session to ensure that the resource-output data is displayed seamlessly on the desktop of the user device. Seamless display of the resource-output data refers to the presentation of the data on the user desktop in a manner that is consistent with how locally-executing resources are presented and manipulated in the local desktop of the user device. A user may therefore view and interact with the resource-output data generated by the remote resources as if the resources were being executed locally.

0806In one embodiment, the output of the resources is displayed in one or more resource-output windows positioned within a web page displayed by a web browser of the user's device. The resource may be executing on a remote machine <b>30</b> or on a virtual machine executing on the remote machine <b>30</b>. In a further embodiment, the attributes of the resource-output windows can be modified so that the resource-output windows are moveable and resizeable within the boundaries of the web page. In another embodiment, the resource-output windows initially appear within the boundaries of the web page and are subsequently moveable so that they are positioned outside the boundaries of the web page and thus give the appearance that the application-output windows correspond to locally-executing applications rather than to remotely-executing applications. In yet another embodiment, the application-output windows initially appear outside the boundaries of the web page and thus also appear to correspond to locally-executing applications. In one embodiment, the application output displayed in the application-output windows and the attributes of the application-output windows themselves are communicated and manipulated by software processes on the user's device and on the resource servers, without involvement of the web server or web browser that initially provided access to the resources.

0807In more detail and with reference to <figref idref="DRAWINGS">FIG. 33</figref>, a server-based computing architecture <b>3300</b>, capable of providing remote users with web-access to the full functionality of web and legacy applications (e.g., unmodified application programs that are not designed for web-based delivery), includes a client machine <b>10</b> (e.g., any digital data processing device), a web server <b>3304</b>, one or more remote machines <b>30</b> that are either standalone or clustered within a machine farm <b>38</b> and which are preferably protected by a firewall <b>3302</b>, and a data communications network <b>150</b> (e.g., Internet, Intranet, etc.) that provides the necessary connectivity to enable each of these elements to communicate with each other.

0808In other embodiments, the web server <b>3304</b> is a remote machine <b>30</b>. In some of these embodiments, virtual machines may be executing on one or more of the remote machines <b>30</b>, the virtual machines providing computing environments in which a requested resource resides and generates resource-output data.

0809In operation and also with reference to <figref idref="DRAWINGS">FIG. 28</figref>, a user of the client machine <b>10</b> directs a browser <b>2822</b> executing on the client machine <b>10</b> to submit a request for access to particular web page content <b>3306</b> accessible via the web server <b>3304</b>. In one embodiment, the user enters a universal resource locator (“URL”) address into the browser <b>2822</b>. The URL is associated with the web page content <b>3306</b> hosted by the web server <b>3304</b> and the browser <b>2822</b> responds by transmitting the request for access to the appropriate URL address. The web server <b>3304</b> receives the request for access, which typically includes user credential information (e.g., user ID, password, group/project membership identifier, etc.), and authenticates the user to the machine farm <b>38</b> or to the individual servers <b>114</b> that provide at least some of the web page content <b>3306</b>.

0810The web server <b>3304</b> authenticates the user by accessing an authentication process that compares the credentials entered by the user with previously-assigned credentials. In one embodiment, the authentication process and database of previously-assigned credentials are stored and maintained on the web server <b>3304</b>. In other embodiments, the previously-assigned credentials can be stored in the machine farm <b>38</b>, on individual application remote machines <b>30</b>, and/or on an administrative server (not shown) that is coupled to the web server <b>3304</b> via the Internet or other data communication network.

0811In the scenario where the web page content <b>3306</b> corresponds to an enterprise portal, which provides access to a resource set <b>3308</b> (e.g., the set of resources that have been personalized for the user by a portal administrator), the web server <b>3304</b> accesses one or more resource objects <b>3310</b> (e.g., COM-compliant Java objects, ActiveX objects, HTML tags, etc.) that call web server-side scripts to authenticate the user and/or to obtain the resource set <b>3308</b> information associated with the portal and user from the machine farm <b>38</b>. The resource objects <b>3310</b> also include properties that are associated with the user and/or the particular resources <b>3312</b> in the resource set <b>3308</b> that are provided via the portal. The user properties include, for example, group/project information that identifies the particular resources <b>3312</b> and data that the user needs to access in order to allow the user to collaborate with other members of the group/project. The resource properties include, for example, the user's preferences for each of the resources <b>3312</b> in the resource set <b>3308</b>.

0812The scripts called by the resource objects <b>3310</b> establish a network session between the web server <b>3304</b> and the machine farm <b>38</b> via, for example, a central administrative process (not shown), which monitors and controls each resource machine <b>30</b> in the machine farm <b>38</b>. The administrative process selects one or more resource servers, which host the resources <b>3312</b> in the resource set <b>3308</b> specified by the resource objects <b>3310</b>, based, for example, on a server and/or network performance basis. The desired resource set <b>3308</b> can be provided entirely by a single server <b>30</b> by selecting/allocating each resource <b>3312</b> in the resource set <b>3308</b> from a plurality of resources <b>3312</b>, <b>3314</b> hosted on the server <b>30</b>. Alternatively, the resource set <b>3308</b>′ can be provided by a plurality of remote machines <b>30</b> with each machine <b>30</b> hosting at least one of the resources in the resource set <b>3308</b>′.

0813The administrative process launches one or more server agents <b>3316</b> on the selected/allocated remote machines <b>30</b> in response to the scripts called by the resource objects <b>3310</b>. Server agents <b>3316</b> are software processes that execute, initialize, and interact with each of the resources <b>3312</b> in the resource set <b>3308</b> in accordance with the properties specified by the resource objects <b>3310</b>. In one embodiment, there is a server agent <b>3316</b> for each resource <b>3312</b> in the resource set <b>3308</b>. In other embodiments, there is a single server agent <b>3316</b> for the resource set <b>3308</b>, to the extent that all of the resources <b>3312</b> are hosted on the same server <b>30</b>. In yet another embodiment, there is a single server agent <b>3316</b> for each server <b>30</b>. The server agents <b>3316</b> then provide the output of the resources <b>3312</b> in the resource set <b>3308</b> as well as any other information relating to the resource set <b>3308</b> to the web server <b>3304</b>, which subsequently formats the resource set information into the web page content <b>3306</b>. The web page content <b>3306</b> can include application icons corresponding to one or more of the resources <b>3312</b> in the resource set <b>3308</b> as well as resource-output data from one or more of the resources <b>3312</b>. In one embodiment, the resource-output data provided by the resources <b>3312</b> corresponds to graphical data that is formatted to fit into a window, which exhibits attributes (e.g., window position on the web page, size, style, z-order, etc.) as initially specified by the properties of the resource objects <b>3310</b>.

0814In one embodiment and with reference to <figref idref="DRAWINGS">FIG. 34</figref>, the browser <b>2822</b> receives and displays the web page content <b>3306</b> within a browser window <b>3402</b>, which includes many possible graphical user interface (“GUI”) elements (e.g., menu <b>3406</b>, local window <b>3408</b>, etc.) that form the client desktop <b>3410</b> displayed on a display device coupled to the client machine <b>10</b>. In this embodiment, the web page content <b>3306</b> is displayed within a web page <b>3412</b> displayed in the browser window <b>3402</b> and includes one or more resource icons <b>3414</b> and/or one or more resource-output windows <b>3416</b>, which are associated with the resource set <b>3308</b>. In one embodiment, one or more of the resource objects <b>3310</b> also form part of the web page content <b>3306</b> of the web page <b>3412</b> and can therefore set the initial attributes (size, z-order, position) of the resource-output windows <b>3416</b>. The initial orientation, size, position, and z-order of each of the resource-output windows <b>3416</b> displayed on the web page <b>3412</b> can be modified, as described below, so that the resource-output windows <b>3416</b> exhibit different orientations, sizes, positions, and z-orders relative to the web page <b>3412</b> and/or relative to the client desktop <b>3410</b>.

0815The resource objects <b>3310</b> can be any data constructs which indicate to the browser <b>2822</b> displaying the web page content <b>3306</b> that a resource-output window <b>3416</b> should be displayed at a particular location in the web page <b>3412</b>. The resource objects <b>3310</b> may include additional information, such as the height, width, border style, background color or pattern in the resource-output window <b>3416</b>, along with indicia of which resources <b>3312</b> may be displayed in the window <b>3416</b>, how often the output display should be updated, or any other additional information that is useful to enhance the display of the resource output.

0816In one embodiment, the resource objects <b>3310</b> are window tags that are embedded in an HTML file, examples of such tags are delineated below.

0000<tables id="TABLE-US-00008" num="00008"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="offset" colwidth="14pt" align="left" /><colspec colname="1" colwidth="203pt" align="left" /><thead><row><entry /><entry namest="offset" nameend="1" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>ActiveX tag</entry></row><row><entry /><entry> <object classid=“clsid:238f6f83-b8b4-11cf-8771-00a024541ee3”</entry></row><row><entry /><entry> data=“/ica/direct.ica” CODEBASE=“/cab/wfica.cab”</entry></row><row><entry /><entry> width=436 height=295></entry></row><row><entry /><entry> <param name=“Start” value=“Auto”></entry></row><row><entry /><entry> <param name=“Border” value=“On”></entry></row><row><entry /><entry>  </object></entry></row><row><entry /><entry>Netscape Plugin tag</entry></row><row><entry /><entry> <embed src=“http://www.citrix.com/ica/direct.ica”</entry></row><row><entry /><entry> pluginspage=“http://www.citrix.com/plugin.html”</entry></row><row><entry /><entry> height=295 width=436 Start=Auto Border=On></entry></row><row><entry /><entry>  <embed></entry></row><row><entry /><entry>JAVA tag</entry></row><row><entry /><entry> <applet code=JICA.class width=436 height=295></entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="14pt" align="left" /><colspec colname="1" colwidth="98pt" align="left" /><colspec colname="2" colwidth="105pt" align="left" /><tbody valign="top"><row><entry /><entry> <param name=Address</entry><entry>value=“128.4.1.2602”></entry></row><row><entry /><entry> <param name=InitialProgram</entry><entry>value=Microsoft Word 7.0></entry></row><row><entry /><entry> <param name=Start</entry><entry>value=Auto></entry></row><row><entry /><entry> <param name=Border</entry><entry>value=On></entry></row><row><entry /><entry>  </applet></entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0817In each case above, the tag indicates that a resource-output window <b>3416</b> having a height of 295 pixels and a width of 436 pixels should be drawn to receive output data from the resource <b>3312</b>. Each tag also specifies that the resource <b>3312</b> should automatically start execution and that the resource-output window <b>3416</b> in which the resource output is displayed should be drawn with a border. The ActiveX and Netscape Plugin tags have the properties of the remote resource <b>3312</b> specified in the file “direct.ica” located in the directory “/ica.” The JAVA tag specifies the properties of the remote resource <b>3312</b> directly. In the example above, the address of the server <b>30</b> hosting the resource <b>3312</b> is specified as well as the name of the resource <b>3312</b> to be executed.

0818In one embodiment, the resource <b>3312</b> executes substantially at the same time as the display of the web page <b>3412</b>. In another embodiment, the resource <b>3312</b> executes when instructed to do so by the server <b>30</b> as part of providing web page content <b>3306</b> to the web server <b>3304</b>. In yet another embodiment, the resource executes in response to a signal, such as a user-specified input (e.g., selecting a resource icon <b>3414</b> on the web page <b>3412</b>. Once execution of the resource <b>3312</b> is commenced, the browser <b>2822</b> instantiates a client agent <b>2814</b> on the client machine <b>10</b>. Alternatively, the client agent <b>2814</b> is instantiated substantially at the same time as the display of the web page <b>3412</b> or in response to user-specified inputs.

0819The client agent <b>2814</b> comprises one or more software processes, which execute on the client machine <b>10</b> and which are configured to interact with the server agent <b>3316</b>, browser <b>2822</b>, resource-output window <b>3416</b>, and/or web server <b>3304</b>. In one embodiment, the client agent <b>2814</b> is spawned as a child process of the browser <b>2822</b>. In other embodiments, the client agent <b>2814</b> is a peer process of the browser <b>2822</b> or a dynamically linked library associated with the browser <b>2822</b>. In one embodiment, a client agent <b>2814</b> is instantiated for each resource-output window <b>3416</b> displayed in the web page <b>3412</b>. In another embodiment, a single client agent <b>2814</b> is instantiated for one or more resource-output windows <b>3416</b> associated with a particular one of the resources <b>3312</b> in the resource set <b>3308</b>. In yet another embodiment, a single client agent <b>2814</b> is instantiated for each server agent <b>3316</b>, which contributed to the web page content <b>3306</b>. In yet another embodiment, a single client agent <b>2814</b> is instantiated for the entire resource set <b>3308</b>.

0820The browser <b>2822</b> passes the properties of the resource objects <b>3310</b> relating to particular resources <b>3312</b> in the resource set <b>3308</b> to the client agent <b>2814</b> associated with those same resources <b>3308</b>. Additionally, the browser <b>2822</b> may pass a handle for a resource-output window <b>3416</b> to the client agent <b>2814</b> or the client agent <b>2814</b> may query the browser <b>2822</b> to retrieve the handle for the resource-output window <b>3416</b>. Resource properties, which are not specified by either the browser <b>2822</b> or the resource objects <b>3310</b>, may be set to default values. The client agent <b>2814</b> may also have certain property defaults hard-coded, or the client agent <b>2814</b> may access a file which contains property defaults.

0821The client agent <b>2814</b> uses the name of the resource <b>3312</b> and the address of the resource server <b>30</b>, which are both provided as part of the properties of the resource objects <b>3310</b>, to establish a communications link and initiate a client-server session with the server agent <b>3316</b> associated with the resource server <b>30</b> and resource <b>3312</b>. The client agent <b>2814</b> passes some or all of the properties of the resource objects <b>3310</b> to the server agent <b>3316</b> along with any necessary default values. Alternatively, the server agent <b>3316</b> may have already received some or all of the properties of the resource objects <b>3310</b> from the web server <b>3304</b> prior to contributing to the web page content <b>3306</b>, which was subsequently displayed in the web page <b>3412</b>. If a particular property is not passed to the server agent <b>3316</b>, the server agent <b>3316</b> may request it from the client agent <b>2814</b> if it is a necessary property to which it has no default value (e.g., user ID) or the server agent <b>3316</b> may provide its own default value for the property (e.g., execution priority).

0822The server agent <b>3316</b> uses the properties received from the client agent <b>2814</b> to authenticate the client agent <b>2814</b> and to execute the desired resource <b>3312</b> if it has not previously been started. Once the resource <b>3312</b> is executing and the client agent <b>2814</b> has been authenticated, the resource <b>3312</b> communicates through the server agent <b>130</b> directly with the client agent <b>2814</b>, without intervention of the browser <b>2822</b> or web server <b>3304</b>. The client agent <b>2814</b> receives output data from the resource <b>3312</b> and displays the output data in the appropriate resource-output window <b>3416</b> in the web page <b>3412</b>. The client agent <b>2814</b> also detects input events, such as mouse clicks and keyboard inputs, associated with the resource-output window <b>130</b> and forwards any such input events to the resource <b>3312</b> via the server agent <b>3316</b>. This type of client-server session is repeated for each resource <b>3312</b> in the application set <b>126</b> that is selected by the user and thus enables the user to interact with all of the resources in the resource set <b>3308</b>.

0823The data exchanged between the client agent <b>2814</b> and server agent <b>3316</b> during the client-server session includes not only input events and the graphical output data of the resource <b>3312</b>, but also window attribute information (e.g., window position, z-order, size, style, color, etc.). The window attribute information of the resource-output windows <b>3416</b> is initially specified by the resource objects <b>3310</b> embedded in the web page <b>3412</b>. For example, the resource objects <b>3310</b> can include an ActiveX control, which specifies and controls the window attributes of the resource-output windows <b>3416</b> during the client-server session. In one embodiment, the resource-output windows <b>3416</b> exhibit the same dimensions as the corresponding ActiveX controls.

0824The client agent <b>2814</b> communicates the initial window attributes of the local application-output windows to the server agent <b>3316</b> along with information relating to the client desktop <b>3410</b> (e.g., size, resolution, etc.). The server agent <b>3316</b> responds by conforming the size of its server desktop to that of the client desktop <b>3410</b> and by conforming the window attributes of local server windows to those of the resource-output windows <b>3416</b> on the client desktop <b>3410</b>. The resource-output windows <b>3416</b> on the client desktop <b>3410</b> and the server windows on the server desktop thus exhibit the same window attributes and display the same graphical output data that is generated by the resource <b>3312</b>. Note that the server desktop can correspond to either an offscreen surface contained within the server's video memory or to an onscreen surface displayed on a display device coupled to the server <b>30</b>.

0825The user of the client machine <b>10</b> can move, resize, and/or alter the z-order or other initial window attributes of the resource-output windows <b>3416</b> during the client-server session, by entering an input event that is detected by the client agent <b>2814</b> and then communicated to the server agent <b>3316</b>. The server agent <b>3316</b> conforms its desktop and/or windows to be consistent with the input event and then transmits updated graphical output data and window attribute information, corresponding to the input event, to the client agent <b>2814</b> with instructions to update the resource-output windows <b>3416</b> so that they match the windows on the server <b>30</b>.

0826For example, if the user of the client machine <b>10</b> resizes one of the resource-output windows <b>3416</b> from that originally specified by the resource objects <b>3310</b> (such as by clicking with the mouse and dragging the border of the application-output window <b>3416</b> to the desired location/size), the client agent <b>2814</b> detects the input event generated by the mouse action and communicates it to the server agent <b>3316</b>, which effects the same resize event in the on or offscreen surfaces of the server <b>30</b>. The server agent <b>3316</b> then sends repaint and resizes command messages to the client agent <b>2814</b> along with updated graphical output data and window attribute information. In response, the client agent <b>2814</b> modifies the appropriate resource object <b>3310</b> affected by the resize event (e.g., the ActiveX control discussed above) so that the corresponding resource-output window <b>3416</b> is resized and the updated graphical output data is painted within the borders of the output window <b>3416</b>.

0827These embodiments thus enable the window attributes of the resource-output window <b>3416</b> to be modified so that the resource-output window <b>3416</b> can be moved, resized, etc., within the boundaries of the browser window <b>3402</b>. With reference to <figref idref="DRAWINGS">FIG. 35</figref> and by way of nonlimiting example, resource-output window B′ <b>3502</b> can be resized using the methodology described above to form resource-output window B″ <b>3504</b>, which overlaps (thus exhibiting a different z-order from) resource-output window F <b>3506</b>. Alternatively, the resource-output window <b>3416</b> can be moved or resized to extend beyond or be entirely outside of the browser window <b>3402</b>. By way of nonlimiting example and with reference to <figref idref="DRAWINGS">FIG. 36</figref>, resource-output window J <b>3602</b> lies within the boundaries of the browser window <b>3402</b>, while resource-output window K <b>3604</b> extends beyond the boundaries of the browser window <b>3402</b> and resource-output window L <b>3606</b> is entirely outside the browser window <b>3402</b>. Note that the resource-output windows can exhibit varying z-orders with respect to other elements in the client desktop <b>3410</b>. For example, local window <b>3608</b> exhibits a z-order between that of the browser window <b>3402</b> and resource-output window L <b>3606</b>. In this embodiment, the client agent <b>2814</b> instructs the operating system of the client machine <b>10</b> to draw the desired resource-output window <b>3416</b> in response to command messages received from the server agent <b>3316</b>, without having to first modify the properties of the resource objects <b>3310</b> embedded in the web page <b>3412</b>, which initially established the window attributes of the resource-output window <b>3416</b>.

0828In one embodiment, each input event affecting the resource-output window <b>3416</b> is transferred to and processed by the server agent <b>3316</b>, which then instructs the client agent <b>2814</b> to effect corresponding changes in the resource-output window <b>3416</b>. In another embodiment, one or more input event types (e.g., click and drag mouse actions directed at moving the resource-output window <b>3416</b> to another grid location on the web page <b>3412</b>) are processed entirely by the client agent <b>2814</b> and not reported to the server agent <b>3316</b>, where the graphical output data displayed within the resource-output window <b>3416</b> remains unchanged.

0829In more detail and with reference to <figref idref="DRAWINGS">FIG. 37</figref>, the client agent <b>2814</b> comprises a monitor process <b>3702</b>, a command process <b>3704</b>, a message receiving process <b>3706</b>, and a message transmission process <b>3708</b>. In one embodiment, each process <b>3702</b>, <b>3704</b>, <b>3706</b>, <b>3708</b> is a separately functioning code segment that operates independently of the other processes. For example, the message receiving process <b>3706</b> and the command process <b>3704</b> can be implemented as separate threads, which communicate with each other via a named pipe or shared memory. Use of a common data set allows the message receiving process <b>3706</b> and the message transmission process <b>3708</b> to be synchronized.

0830The message receiving process <b>3706</b> receives graphical data, window attribute information, and commands from the server agent <b>3316</b> via the communications link that provides the connectivity between the client agent <b>2814</b> and server agent <b>3316</b> during the client-server session. The communications link preferably includes a first virtual channel <b>3710</b> and a second virtual channel <b>3712</b>. Command, event, and window attribute information is passed between the client agent <b>2814</b> and the server agent <b>3316</b> via the first virtual channel <b>3710</b>, while graphical data corresponding to the graphical contents of the resource-output windows <b>3416</b> is passed via the second virtual channel <b>3712</b>. The message receiving process <b>3706</b> informs the command process <b>3704</b> of the commands, window attributes, and graphical data received from the server agent <b>3316</b> and the command process <b>3704</b> further processes this data.

0831In one embodiment, the command process <b>3704</b> processes the commands received from the server agent <b>3316</b> by instructing the client operating system <b>3714</b> to form and/or modify affected resource-output windows <b>3416</b> in accordance with the window attributes specified by the server agent <b>3316</b>. The command process <b>3704</b> also instructs the client operating system <b>3714</b> to display the graphical data provided by the server agent <b>3316</b> in the appropriate resource-output windows <b>3416</b>. In one embodiment, the command process <b>3704</b> implements changes to the resource-output windows <b>3416</b> in the client desktop <b>3410</b> by issuing GDI commands. In other embodiments, the command process <b>3704</b> issues commands directly to an associated graphics subsystem or via graphics API commands.

0832The command process <b>3704</b> also instructs the monitor process <b>3702</b> to periodically monitor the client desktop <b>3410</b> in order to detect changes affecting the resource-output windows <b>3416</b>. In one embodiment, the monitor process <b>3702</b> instructs the client operating system <b>3714</b> to return information relating to the client desktop <b>3410</b> at predetermined polling intervals. In other embodiments, the monitor process <b>3702</b> monitors the message queue maintained by the client operating system <b>3714</b> in order to detect changes affecting the resource-output windows. The monitor process <b>3702</b> communicates some or all of the detected desktop changes to the command process <b>3704</b> for further processing.

0833In one embodiment, the command process <b>3704</b> instructs the message transmission process <b>3708</b> to transmit all of the changes detected by the monitor process <b>3702</b> to the server agent <b>3316</b> via the first virtual channel. In another embodiment, the command process <b>3704</b> instructs the message transmission process <b>3708</b> to transmit a subset of the detected changes, such as changes which only affect the graphical data and/or window attributes of the resource-output windows <b>3416</b>. The server agent <b>3316</b> receives the detected changes along with any commands from the command process <b>3704</b> and any input events made by the user of the client machine <b>10</b> that triggered the detected changes. The server agent <b>3316</b> then modifies its local desktop to accommodate the detected changes and transmits associated commands, window attributes, and graphical data back to the client's message receiving process <b>3706</b>. In this manner, desktop elements, such as the resource-output windows <b>3416</b>, that are common in the client and server desktops remain in lock step.

0834The command process <b>3704</b> of the client agent <b>2814</b> ensures that analogous/common elements in the client and server desktops remain in lock step by maintaining a common window list. The common window list includes the window attribute information for each window in the client desktop <b>3410</b> and for each corresponding window in the resource server desktop. In embodiments, in which a plurality of client agents is executing on the client machine <b>10</b>, the command process <b>3704</b> of a single client agent <b>2814</b> has primary responsibility for maintaining the common window list. If the single client agent <b>2814</b> terminates, while other client agents remain in operation, the remaining client agents will elect another primary client agent to maintain the common window list.

0835<figref idref="DRAWINGS">FIG. 38</figref> depicts a system in which a client machine <b>10</b> is connected to more than one remote machine <b>30</b>, <b>30</b>′. As shown in <figref idref="DRAWINGS">FIG. 38</figref>, client machine <b>10</b> has an associated display <b>3802</b>. The display <b>3802</b> may be used to display one or more components of a graphical user interface, such as windows and pull-down menus. The collection of graphical user interface components displayed to a user by the display <b>3802</b> is generally referred to as the “desktop.” As shown in <figref idref="DRAWINGS">FIG. 38</figref>, the client machine <b>10</b> displays a local desktop environment <b>3804</b> to a user. Client machine <b>10</b> may provide at least a part of the local desktop environment <b>3804</b> or client machine <b>10</b> may simply display various desktop components received from other sources such as remote machines <b>30</b>. As shown in <figref idref="DRAWINGS">FIG. 38</figref>, each remote machine <b>30</b>, <b>30</b>′ has an associated display <b>3806</b>, <b>3806</b>′ which also displays a desktop environment <b>3808</b>, <b>3808</b>′. It should be noted that display <b>3806</b>, <b>3806</b>′ need not be a video display monitor. For example, display <b>3806</b>, <b>3806</b>′ may simply be a bank of video RAM to which resources write the output of graphical procedure calls. <figref idref="DRAWINGS">FIG. 38</figref> depicts an embodiment of a system in which each machine <b>30</b> displays <b>3806</b>, <b>3806</b>′ displays one graphical user interface window <b>3810</b>, <b>3812</b>′.

0836Each remote machine <b>30</b>, <b>30</b>′ also includes at least one agent <b>3814</b>, <b>3814</b>′. In some embodiments, each remote machine <b>30</b>, <b>30</b>′ includes one agent <b>3814</b>, <b>3814</b>′ for each client machine <b>10</b> connected to the remote machine <b>30</b>, <b>30</b>′. Client machine <b>10</b> may also host an agent <b>3816</b>. In some embodiments, a client machine <b>10</b> hosts a separate local agent <b>3816</b> for each remote machine <b>30</b> to which the client machine <b>10</b> is connected. In other embodiments, the client machine <b>10</b> hosts a single agent <b>3816</b> that manages connections to multiple remote machines <b>30</b>. Each of the agents <b>3814</b>, <b>3814</b>′, <b>3816</b> may monitor their associated desktop environment <b>3808</b>, <b>3808</b>′, <b>3816</b> for windows which: change position; are opened; are closed; change size; are minimized; are maximized; or are brought to the top of the desktop, i.e., windows which gain focus that do not previously have focus. Each agent <b>3814</b>, <b>3814</b>′, <b>3816</b> transmits messages indicative of changes in their associated desktop <b>3808</b>, <b>3808</b>′, <b>3804</b> to other agents. For example, local agent <b>3816</b> may receive messages transmitted from server node agents <b>3814</b>, <b>3814</b>′. The local agent <b>3816</b> commands the client machine <b>10</b> to modify the local desktop environment <b>3804</b> in response to the messages received from server agents <b>3814</b>, <b>3814</b>′, that is, the local agent <b>3816</b> issues commands to the client machine <b>10</b> to conform the local desktop environment <b>3804</b> to the desktop environment <b>3804</b> In other embodiments, agents <b>3814</b>, <b>3814</b>′ for remote machine <b>30</b>, <b>30</b>′ receive messages from a local agent <b>3816</b> and command the machine <b>30</b>, <b>30</b>′ to modify the desktop environment <b>3808</b>, <b>3808</b>′ in response to messages received from the local agent <b>3816</b>.

0837In one embodiment, the agents <b>3814</b>, <b>3816</b> monitor changes to their associated desktop environment <b>3808</b>, <b>3808</b>′ by periodically issuing one or more of a set of commands provided by the operating system that allow details of the graphical user interface desktop to be determined. For embodiments in which the agents <b>3814</b>, <b>3816</b> reside on nodes that execute a version of the WINDOWS operating system, the agents <b>3814</b>, <b>3816</b> may periodically issue the Enum Windows command to the WINDOWS operating system, which returns a list of all windows present on the desktop, together with information related to those windows. The agents <b>3814</b>, <b>3816</b> can issue the Enum Windows command every 50 milliseconds, every 100 milliseconds, every 500 milliseconds, or at any period that allows the agent <b>3814</b>, <b>3816</b> to rapidly determine when changes to its associated desktop environment have occurred without putting a significant computational burden on the node. In this embodiment, the agent <b>3814</b>, <b>3816</b> maintains a data structure storing information about the desktop windows and compares the values returned by the Enum Windows command to the data structure to determine changes.

0838Information determined and stored by the agent <b>3814</b>, <b>3814</b>′ can include the title bar associated with each window, the location of each window in the desktop environment <b>3808</b>, <b>3808</b>′, the size of each window, and the z-order positioning of each window in the desktop environment <b>3808</b>, <b>3808</b>′. In another embodiment, the agent <b>3814</b>, <b>3814</b>′, <b>3816</b> monitors an intranode graphics message queue to determine changes to its associated desktop environment. Server agents <b>3814</b>, <b>3814</b>′ monitor an intraserver message queue and local agent <b>3816</b> monitors an intraclient message queue. In this embodiment, changes to the desktop environment <b>3808</b>, <b>3808</b>′ are affected via messages sent to a graphics subsystem from system applications or the operating system itself. Thus, a resource executing on a remote machine <b>30</b>, <b>30</b>′ would send a message to a graphics engine residing on the server <b>30</b>, <b>30</b>′ in order to change the server desktop environment <b>3808</b>, <b>3808</b>′. Other commands which return graphical user interface data are readily apparent to those of ordinary skill in the art. For embodiments in which the agents <b>3814</b>, <b>3816</b> reside on nodes executing a version of the WINDOWS operating system, the agents <b>3814</b>, <b>3816</b> monitor the Windows Message Queue for messages affecting the desktop environment associated with the node on which the agent resides. Examples of such messages include: WM_SETFOCUS, which indicates to which window focus will be given (i.e., brought to the “top” of the desktop); WM_KILLFOCUS, which removes focus from an indicated window; and WM_WINDOWPOSCHANGING, which indicates a change in the position of a window. Other messages that can be posted to the Windows Message Queue are readily known to those of ordinary skill in the art.

0839Referring now to <figref idref="DRAWINGS">FIG. 39</figref>, the steps taken during a server-initiated event are shown. The agent <b>3814</b> for remote machine <b>30</b> senses a change in its associated desktop (step <b>3902</b>). The agent <b>3814</b> may do this by intercepting a window event on the server message queue, or the agent <b>3814</b> may determine a change in the desktop by comparing the results returned from serially issued operating system commands, as described above. The agent <b>3814</b> sends a message to a client agent <b>3816</b> indicating the change in the server desktop <b>3810</b> (step <b>3904</b>). For example, if a new window has been given focus, the agent <b>3814</b> can transmit a message to a client agent <b>3816</b> indicating the identity of the new “top” window. In one embodiment, the agent <b>3814</b> broadcasts its message to all client agents <b>3816</b> that exist in the system. Alternatively, the agent <b>3814</b> may transmit its message only to a predetermined subset of client agents <b>3816</b>. For example, when a client machine <b>10</b> makes a connection to a remote machine <b>30</b>, the client agent <b>3816</b> may register with the agent <b>3814</b>. In this embodiment, the agent <b>3814</b> would transmit change messages only to those client agents that have registered with the remote machine <b>30</b>.

0840The client agent <b>3816</b> receives the transmitted message (step <b>3906</b>). In embodiments in which the remote machine <b>30</b> broadcasts commands, the client agent <b>3816</b> must have some mechanism for determining whether a transmitted command affects its associated desktop. For example, the client agent <b>3816</b> may maintain a list of remote machines <b>30</b> to which it is connected. In these embodiments, the client agent <b>3816</b> responds to messages broadcast by any remote machine <b>30</b> present in its list. For embodiments in which the agent <b>3814</b> does not broadcast messages, no such mechanism is necessary.

0841The client agent <b>3816</b> implements a change to its associated desktop <b>14</b> responsively to the received message (step <b>3908</b>). The client agent <b>3816</b> may accomplish this by directly issuing graphics Application Programming Interface commands that cause the client machine <b>10</b> to change the display of its associated desktop. Alternatively, the client agent <b>3816</b> may issue GDI commands to change its associated desktop. In still other embodiments, the client agent <b>3816</b> issues commands directly to the system, whether implemented in hardware or software, responsible for displaying graphics on the client machine <b>10</b>.

0842Referring now to <figref idref="DRAWINGS">FIG. 40</figref>, the steps taken when a client machine <b>10</b> initiates a desktop change are shown. The client agent <b>3816</b> senses a change in its associated desktop <b>14</b> (step <b>4002</b>). As noted above, this may be done on an event-driven basis or by polling the operating system operating on the client machine <b>10</b>. The client agent <b>3816</b> determines to which remote machine <b>30</b> the affected window belongs (step <b>4004</b>). To facilitate this process, the client agent <b>3816</b> may maintain a list that associates remote windows with a particular remote machine <b>30</b>. The client agent <b>3816</b> then sends a message to the identified remote machine <b>30</b> indicating the change in its desktop <b>14</b> (step <b>4006</b>). Alternatively, the client agent <b>3816</b> may skip step <b>404</b> entirely and broadcast its change message to all remote machines <b>30</b>. The server agent receives the transmitted message (step <b>4008</b>) and implements the change in its associated desktop (step <b>4010</b>), as described above.

0843In one particular embodiment, a client machine <b>10</b> and a remote machine <b>30</b> communicate using the ICA protocol and the client machine <b>10</b> and the remote machine <b>30</b> execute a version of the WINDOWS operating system. Client machine <b>10</b> hosts a local agent <b>3816</b> that may be provided as a dynamically linked library module. The remote machine <b>30</b> hosts an agent <b>3814</b> that may be provided as a separate thread.

0844In this embodiment, the local agent <b>3816</b> and the agent <b>3814</b> exchange graphical data, i.e., the data actually displayed in each window on the desktop, via a first ICA virtual channel. Information about window positioning, window size, z-access ordering of window and other such information is communicated between the client machine <b>10</b> and the remote machine <b>30</b> via a second ICA virtual channel. Throughout the description, when the client machine <b>10</b> and the remote machine <b>30</b> are actively exchanging information via the second ICA virtual channel, the client machine <b>10</b> will be referred to as being in “seamless windowing mode.”

0845Referring now to <figref idref="DRAWINGS">FIG. 41</figref>, the process for enabling seamless windowing mode between the local agent <b>3816</b> and agent <b>3814</b> is shown. In this embodiment, all communication between a server agent and a client agent is packet-oriented and takes place over a dedicated ICA virtual channel, making the functioning of the agents <b>3814</b>, <b>3816</b> independent from the underlying communication protocol. All packets start with packet type (1 byte), followed by packet data length (2 bytes, can be zero) and data (optional). Agents <b>3814</b>, <b>3816</b> will try to send as much data in a single network packet as possible, but it will always send complete packets. That is, the size of seamless window virtual packets never exceeds the allowable size of an ICA packet. Packet flow control and delivery confirmation is implemented by the transport level of the ICA protocol. Individual packets are executed immediately on reception.

0846The client agent <b>3816</b> waits for an initial packet from the server agent <b>3814</b>. After user logon to the server, a server agent <b>3814</b> will be invoked (step <b>4104</b>).

0847The server agent <b>3814</b> sends a TWI_PACKET_START packet to the client agent <b>3816</b>, which includes some essential information about the remote machine <b>30</b> desktop environment (desktop resolution, desktop size, version number of ICA protocol supported by the server, etc.) (step <b>4106</b>). This packet is sent by the server agent <b>3814</b> on initial connection or on reconnect, and is used to: (1) detect seamless windowing capabilities of the client machine <b>10</b>; and (2) requests basic machine <b>10</b> information.

0848The client agent receives the TWI_PACKET_START packet (step <b>4107</b>) and responds with a TWI_PACKET_C2H_START_ACK packet, confirming TWI_PACKET_START and supplying machine <b>10</b> version/capabilities information (step <b>4108</b>). This packet is sent by the client agent <b>3816</b> to confirm reception of TWI_PACKET_START packet and to send the requested basic machine <b>10</b> information to the server agent <b>3814</b>.

0849If there is no response from the client agent <b>3816</b> (step <b>4109</b>), the server agent <b>3814</b> assumes that the client machine <b>10</b> is unable to enter seamless windowing mode, and the seamless windowing virtual channel is not used by the remote machine <b>30</b> to communicate window information. In this case, the remote machine <b>30</b> continues to communicate graphical data to the client machine <b>10</b> via another virtual channel, and the client machine <b>10</b> desktop displays the server desktop without incorporating windows from other nodes.

0850The client agent <b>3816</b> uses the information sent by the server agent <b>3814</b> in step <b>4106</b> to determine if a seamless windowing session can be established between the server agent <b>3814</b> and the client agent <b>3816</b>. In one embodiment, the client agent <b>3816</b> compares information relating to the version of the virtual channel protocol supported by the server agent <b>3814</b> to makes the determination If the client agent <b>3816</b> determines that it is possible to enable seamless windowing mode (step <b>4110</b>), the client agent <b>3816</b> sends a TWI_PACKET_C2H_OPEN packet to the server agent <b>3814</b> (step <b>4111</b>). This packet requests that the server agent <b>3814</b> enable seamless windowing mode.

0851On reception of a TWI_PACKET_C2H_OPEN packet (step <b>4112</b>) the server agent <b>3816</b> (I) resets its internal data structures, (ii) sends a TWI_PACKET_SYSINFO packet to the client agent <b>3816</b> to communicate some general information regarding the window settings on the remote machine <b>30</b> to the client agent <b>3816</b>, (iii) sends a TWI_PACKET_OPEN packet to the client agent <b>3816</b> (step <b>4114</b>) indicating the establishment of seamless windowing mode, and (iv) enables its main polling loop (step <b>4116</b>) that will poll the operating system on the server node for desktop changes. If the client agent <b>3816</b> and the server agent <b>3814</b> do not support the same version of the seamless window protocol, the server agent <b>3814</b> ignores the TWI_PACKET_C2H_OPEN packet.

0852On reception of TWI_PACKET_OPEN packet (step <b>4120</b>), the client agent <b>3816</b> resets its internal data structures (step <b>4122</b>) and seamless windowing mode between the client agent <b>3816</b> and the server agent <b>3814</b> is established.

0853During a seamless windowing mode session, the server agent <b>3814</b> will send window information such as window position, size, styles, window text, etc. for all top-level windows on the server node. Also, foreground window information is sent, i.e., which window on the server node desktop is the foreground window. In accordance with this information, the client agent <b>3816</b> creates windows with the same size/position as the server node windows on the machine desktop. In some embodiments, window elements are transmitted as bitmaps from the server node <b>20</b>. Examples of packets sent by the server agent <b>3814</b> include: TWI_PACKET_CLOSE, which is sent to switch the client agent <b>3816</b> out of seamless windowing mode and back to regular, or full screen, mode; that is, the client machine <b>10</b> is switched back to displaying the server node desktop environment without incorporating windows from other desktop environments; TWI_PACKET_CREATEW, which is sent to create new windows on the client machine <b>10</b>; TWI_PACKET_DELETEW, which is sent to destroy a window on the client machine <b>10</b>; TWI_PACKET_CHANGEW, which is sent to change a window displayed by the local node <b>10</b>; TWI_PACKET_SYSINFO, which is sent to report remote machine <b>30</b> system settings—normally it is sent only once, but the packet can be sent multiple times; TWI_PACKET_FOREGROUNDW, which is sent during normal seamless windowing mode operation to change the foreground window; TWI_PACKET_SETTOPW, which is sent during normal seamless windowing mode operation to change the top window, that is, to bring a new window to top; TWI_PACKET_SETFOCUS, which is sent during normal seamless windowing mode operation to change the focus window; TWI_PACKET_FOCUSACK, which is sent in response to TWI_PACKET_C2H_SETFOCUS (see below), and reports the result of a SetFocus attempt; and TWI_PACKET_SPA_STATUS, which is sent in response to TWI_PACKET_C2H_START_PUBLICAPP (see below), and is used to report the result of the requested operation.

0854Examples of packets that can be sent by the client agent <b>3816</b> to the server agent <b>3814</b> include: TWI_PACKET_C2H_PAUSE, which is sent to suspend the server agent <b>3814</b>, that is, the server agent <b>3814</b> will stop sending window information, clear its internal data structure and send a TWI_PACKET_CLOSE packet (see above); TWI_PACKET_C2H_RESUME, which is sent to resume the server agent <b>3814</b>—the server agent <b>3814</b> will clear its internal data structure, and send a TWI_PACKET_OPEN packet (see above); TWI_PACKET_C2H_SETPOS, which is sent to report window size/position change on the machine; TWI_PACKET_C2H_SETFOCUS, which is sent to report a change in the focus window on the machine; TWI_PACKET_C2H_RESTORE, which is sent to request restoration of a minimized window; TWI_PACKET_C2H_TERMINATE, which is sent to request termination of a program executing on the remote machine <b>30</b>; TWI_PACKET_C2H_STARTAPP, which is sent to start a new resource on the remote machine <b>30</b>; TWI_PACKET_C2H_LOGOUT, which is sent to end the current session; TWI_PACKET_C2H_START_PUBLICAPP, which is sent to start a new published resource on the remote machine <b>30</b>; and TWI_PACKET_C2H_CLIENTINFO, which is sent to report client desktop settings to the server agent <b>3814</b>—this packet is generally sent on startup, but can also be used during seamless windowing session.

0855The client agent <b>3816</b> will try to perform some operations (such as window move and resize) locally, sending update information back to the remote machine <b>30</b> afterwards. Proper window behavior is emulated by intercepting the WM_NCHITTEST message for the client-created windows.

0856Foreground window changes can happen on both the client machine <b>10</b> and the remote machine <b>30</b>, so the client machine <b>10</b> and remote machine <b>30</b> will negotiate and balance actual foreground window changes. For example, if the remote machine <b>30</b> changes its foreground window, that change should be properly represented on the client machine <b>10</b> desktop. The server agent <b>3814</b> sends information regarding the new foreground window to the client agent <b>3816</b> using the TWI_PACKET_FOREGROUNDW packet. Similarly, if the client agent <b>3816</b> detects a foreground window change on the client machine <b>10</b> desktop, the client agent <b>3816</b> sends information regarding the change to the server agent <b>3814</b> and the server agent <b>3814</b> implements the change on the remote machine <b>30</b> desktop.

0857When focus is taken away from a window representing a server window and is given to a local machine <b>10</b> window, the client machine <b>10</b> notifies the remote machine <b>30</b> of the change and the remote machine <b>30</b> gives focus to an invisible window. For embodiments in which the client machine <b>10</b> is connected to two server nodes <b>30</b>, and focus is shifted from a window representing a window from the first remote machine <b>30</b> and is given to a window representing a window from the second remote machine <b>30</b>′, the client machine <b>10</b> sends a packet informing the current remote machine <b>30</b> or <b>30</b>′ that its window no longer has focus. Once the remote machine <b>30</b> or <b>30</b>′ responds by giving focus to an invisible window, the client agent <b>3816</b> instructs the other remote machine <b>30</b> that its window now has focus on the client machine <b>10</b> desktop.

0858In some embodiments, it is desirable to add some complexity to the agent's main polling loop to reduce network traffic. In these embodiments, the main polling loop includes a comparison between the current foreground window and the identity of the window last requested to be moved to the foreground. If the current foreground window matches the window identified in the most recent request, the agent does not need to send information acknowledging the change. This technique is useful in both server agent <b>3814</b> and client agents <b>3816</b>.

0859Window z-ordering on the client machine <b>10</b> is a superset of the server node z-ordering (machine <b>10</b> will always have more windows than the host). Server node Bordering is reproduced on the client machine <b>10</b> by reproducing owner/owned relationship among windows and the TOP_MOST flag in the window style. Owner/owned relationships refer to windows which are children of other windows, such as dialog boxes associated with resource windows. The dialog box is said to be owned by the resource window, and the dialog box will always appear on top of its owner. The TOP_MOST flag indicates that a particular window should appear on “top” of the desktop, for example, the status bar in WINDOWS 95.

0860When a user disconnects, the server agent <b>3814</b> switches itself to suspended mode, and will not send information to the client agent <b>3816</b>. On a reconnect, the server agent <b>3814</b> sends a TWI_PACKET_START packet, reporting HostAgentState as “already running, reconnect.”

0861Based on the version number of the protocol supported by the server the client machine <b>10</b> will decide whether it is possible to enable seamless windowing mode (from the client machine <b>10</b> point of view). If it is possible to switch to seamless windowing mode, the client agent <b>3816</b> will send a TWI_PACKET_C2H_OPEN packet, asking the server agent <b>3814</b> to enable seamless windowing mode.

0862Each agent responsible for monitoring an associated desktop may be implemented as a stand-alone software routine (such as an executable file on DOS-based systems), a dynamically linked library routine (DLL), or as an integral piece of the operating system. Referring now to <figref idref="DRAWINGS">FIG. 42</figref>, and in brief overview, each agent includes a message receiving facility <b>4202</b>, a command facility <b>4204</b>, a monitor facility <b>4206</b>, and a message transmission facility <b>4208</b>. Agent-agent communication is full-duplex, i.e., agents can transmit and receive messages simultaneously. Thus, each facility can be implemented as a separately functioning code segment that operates independently of the other facilities. For example, message receiving facility <b>4202</b> and command facility <b>4204</b> can be implemented as separate threads which communicate with each other via a named pipe or shared memory. Use of a common data allows the message receiving facility <b>4202</b> and the message transmitting facility <b>4208</b> to be synchronized.

0863Message receiving facility <b>4202</b> receives messages transmitted from other agents indicating changes in the desktop environments associated with those agents. Message receiving facility <b>4202</b> may connect directly with the physical layer of the communications protocol the agents use to communicate, or the message receiving facility <b>4202</b> may operate at a higher layer of the protocol by cooperating with one or more communications subsystems. For embodiments in which messages are broadcast by agents, the message receiving facility <b>4202</b> has some mechanism for determining whether a broadcast message is intended for it. For example, the message receiving facility <b>4202</b> may store a list of the windows which its associated desktop displays. The message receiving facility <b>4202</b> would compare the target of any received message to its list of windows to determine whether or not to take action on the received message. The message receiving facility may be implemented as a blocking function. Alternatively, the message receiving facility can be implemented a call-back function invoked by the ICA virtual channel transport.

0864Once the message receiving facility <b>4202</b> has determined that a received message is intended for its desktop, the command facility is invoked to effect the change indicated by the message to the associated desktop environment. The command facility <b>4204</b> may be passed the received message facility, or the message receiving facility <b>4202</b> may process the received message before communicating with the command facility <b>4204</b>. The command facility <b>4204</b> may implement the desktop change indicated by the received message by issuing GDI commands. In other embodiments, the command facility <b>4204</b> may issue commands directly to an associated graphics subsystem or may issue other graphics API commands.

0865During a seamless windowing session, a number of desktops are associated with a single machine <b>10</b>—one desktop on the client machine <b>10</b> itself and one desktop per remote machine <b>30</b> to which the client machine <b>10</b> is connected. The client agent <b>3816</b>, in conjunction with the server agent <b>3814</b>, <b>3814</b>′, creates a combined window list representing the z-order of all desktops. All participating desktops are “linked” together by the client agents <b>40</b> and the server agents <b>3814</b>, <b>3814</b>′, and any z-order changes on any desktops will be propagated to other desktops.

0866In one embodiment, each remote machine <b>30</b> has knowledge only of its own graphical desktop representation and the remote machine <b>30</b> desktops are individually represented within the client machine <b>10</b>. The client machine <b>10</b> display is updated by combining all remote machine <b>30</b> and machine <b>10</b> desktop images into a single display image based on the window information that has been obtained from each server node <b>30</b><b>30</b>′ by the client agent <b>3816</b>. The resulting image is displayed at the client machine <b>10</b>.

0867The combining process involves building a common window list based on the windows information exchanged by all agents. Using the combined window list, the graphical desktop data is clipped and merged for representation by the client machine <b>10</b>. The node takes care of “clipping” displayed windows resulting from the commands issued by the command facility <b>4204</b>. Such “clipping” functions are well-known to those of ordinary skill in the art. In some embodiments, however, the command facility <b>4204</b> maintains a shadow bitmap of clipped windows. That is, the command facility <b>4204</b> maintains a bit image of windows that are obscured by other windows. This allows the agent to change its associated desktop without requiring it to reload the window image of an obscured window from the appropriate source. In other embodiments, the node determines whether graphical data is obscured at the time it is received. If it is, the node ignores the received graphical data. If it is not, the node displays the data. The node makes a determination as to whether the graphical data is obscured by applying clipping functions.

0868Monitoring facility <b>4206</b> monitors the desktop associated with the agent. Monitoring facility <b>4206</b> may monitor the desktop by periodically issuing commands provided by the operating system executing on the node which return information about the node's desktop. Alternatively, the monitoring facility <b>506</b> may watch for messages posted to an intranode message queue. As noted above, in one particular embodiment the monitoring facility <b>4206</b> monitors the Windows Message Queue. Once a desktop change occurred, the message transmission facility <b>4208</b> transmits a message indicating the change that has occurred. In some embodiments, the message transmission facility <b>4208</b> broadcasts notification of the change.

0869In one embodiment, message transmission facility <b>4208</b> can be implemented in the form of non-blocking function that can be called from any window procedure. If the function can not send a data packet immediately (for example, the communication subsystem has no buffer space), a timer will be set and retry attempts will be done until the send succeeds.

0870Referring now to <figref idref="DRAWINGS">FIG. 43</figref>, an embodiment of a system for enabling seamless windowing mode between a client machine <b>10</b> and remote computing environments is shown. In brief overview, the system includes a first virtual channel <b>4302</b>, a first remote desktop environment <b>4304</b>, a native operating system <b>4306</b>, a remote window <b>4308</b>, a second virtual channel <b>4310</b>, a third virtual channel <b>4312</b>, a second remote desktop environment <b>4314</b>, a virtualized operating system <b>4316</b>, a remote window <b>4318</b>, a fourth virtual channel <b>4320</b>, a local agent <b>4330</b>, and a local desktop environment <b>4340</b>.

0871In some embodiments the methods and systems described above in connection with <figref idref="DRAWINGS">FIGS. 24-37</figref> may be implemented in systems including virtual machines. In some embodiments, the local agent <b>4330</b> resides on a client machine <b>10</b>. In one of these embodiments, the client machine <b>10</b> establishes a connection to a physical machine providing access to a resource requested by the client machine <b>10</b>. In this embodiment, the local agent <b>4330</b> on the client machine <b>10</b> may receive window attribute data and graphical data associated with a remote window <b>4308</b> from an agent on a remote machine <b>30</b> as described above.

0872In other embodiments, the client machine <b>10</b> has established a connection to a virtual machine providing access to a resource. In one of these embodiments, an agent for the remote machine <b>30</b> may reside in the virtual machine. In another of these embodiments, the agent for the remote machine <b>30</b> may reside in a hypervisor into which the virtual machine is launched. In still another of these embodiments, the agent for the remote machine <b>30</b> may reside in a second virtual machine providing management functionality for the virtual machine on the remote machine <b>30</b>. In these embodiments, the client machine <b>10</b> may receive window attribute data and graphical data associated with a remote window <b>4308</b> through the implementation of the methods and systems described above in connection with <figref idref="DRAWINGS">FIGS. 24-37</figref>.

0873The client machine <b>10</b> may access multiple resources from different remote machines <b>30</b>. In some embodiments, the client machine <b>10</b> may access resources on different machines substantially simultaneously over multiple established connections to, for example, both physical machines on remote machines <b>30</b> and to virtual machines executing in a hypervisor on remote machines <b>30</b>′.

0874Referring still to <figref idref="DRAWINGS">FIG. 43</figref>, and in greater detail, a block diagram depicts one embodiment of a system for receiving window attribute data and graphical data associated with remote windows from virtualized operating systems and from native operating systems. The first virtual channel <b>4302</b> is coupled to the first remote desktop environment <b>4304</b>, which is provided by the native operating system <b>4306</b>. The first virtual channel <b>4302</b> conveys graphical data associated with the remote window <b>4308</b> provided by the first remote desktop environment <b>4304</b>. The second virtual channel <b>4310</b> coupled to the first remote desktop environment <b>4304</b> conveys window attribute data associated with the remote window <b>4308</b> provided by the first remote desktop environment <b>4304</b>.

0875The third virtual channel <b>4312</b> is coupled to the second remote desktop environment <b>4314</b> provided by a virtualized operating system <b>4316</b>, the third virtual channel <b>4312</b> conveying graphical data associated with the second remote window <b>4318</b> provided by the third remote desktop environment <b>4314</b>. The fourth virtual channel <b>4320</b> coupled to the second remote desktop environment <b>4314</b> and conveying window attribute data associated with the second remote window <b>4318</b> provided by the second remote desktop environment <b>4314</b>. In one embodiment, the window attribute data associated with the remote windows <b>708</b> and <b>718</b> and conveyed by the second virtual channel <b>4310</b> and the fourth virtual channel <b>4320</b> includes the size and z-order of the remote windows.

0876The local agent <b>3814</b>, coupled to the first remote desktop <b>4304</b> and the second remote desktop <b>4314</b> via the first, second, third and fourth virtual channels directs the formation of a first window in the local desktop environment <b>4340</b> corresponding to the remote window <b>4308</b> provided by the first remote desktop environment <b>4304</b> and the formation of a second window in the local desktop environment <b>4340</b> corresponding to the second remote window <b>4318</b> provided by the second remote desktop environment <b>4314</b>. The first local window displays the graphical data conveyed by the first virtual channel <b>4302</b> in accordance with the window attribute data conveyed by the second virtual channel <b>4310</b> and the second local window displaying the graphical data conveyed by the third virtual channel <b>4312</b> in accordance with the window attribute data conveyed by the fourth virtual channel <b>4320</b>. In one embodiment, the local agent <b>4330</b> forms and maintains a combined windows list representing a modifiable z-order of a corresponding window in the local desktop environment <b>4340</b>.

0877In some embodiments, a local operating system forms the local desktop environment <b>4340</b>. In one of these embodiments, the local agent <b>4330</b> periodically polls the local operating system to detect an attribute change in one of the first local window and the second local window. In another of these embodiments, upon detection of attribute change, the local agent <b>4330</b> transmits a message to one of the first remote desktop environment and the second remote desktop environment indicative of the attribute change. In some embodiments, corresponding windows on the local desktop environment <b>4340</b> and on the remote desktop environments <b>4304</b> and <b>4314</b> exhibit window attribute data substantially similar relative to the local desktop environment as to the window attribute data of the remote windows relative to their respective remote desktop environment.

0878Referring now to <figref idref="DRAWINGS">FIG. 44</figref>, a flow diagram depicts one embodiment of the steps taken in a method of receiving window attribute data and graphical data associated with remote windows from virtualized operating systems and from native operating systems. In brief overview, graphical data associated with a remote window provided by a first remote desktop environment provided by a native operating system is received via a first virtual channel coupled to the remote desktop (step <b>4302</b>). Window attribute data associated with the remote window provided by the first remote desktop environment is received via a second virtual channel coupled to the first remote desktop environment (step <b>4304</b>). Graphical data associated with a remote window provided by a second remote desktop environment provided by a virtualized operating system is received via a third virtual channel coupled to the remote desktop environment (step <b>4306</b>). Window attribute data associated with the remote window provided by the second remote desktop environment is received via a fourth virtual channel coupled to the second remote desktop environment (step <b>4308</b>). A first window is formed in the local desktop environment, the first window displaying the graphical data received from the first virtual channel in accordance with the window attribute data received from the second virtual channel (step <b>4310</b>). A second window is formed in the local desktop environment, the second window displaying the graphical data received from the third virtual channel in accordance with the window attribute data received from the fourth virtual channel (step <b>4312</b>).

0879In some embodiments, a combined windows list is formed and stores at least some of the window attribute data. In other embodiments, a local operating system associated with the local desktop environment is polled to detect an attribute change in one of the first local window and the second local window and transmitting a message to one of the first remote desktop environment and the second remote desktop environment indicative of the detected attribute change. In still other embodiments, the local windows exhibit window attribute data substantially similar relative to the local desktop environment as the window attribute data of the remote windows relative to the remote desktop environments.

0880Referring to <figref idref="DRAWINGS">FIG. 45</figref>, one embodiment of a system for providing a client with a reliable connection to a host service is shown. In a broad overview, a system <b>4500</b> for network communications includes a client machine <b>10</b> (e.g., a first computing device) in communication with a first protocol service <b>4502</b> (e.g., a second computing device) over a network <b>150</b>. Also included in the system <b>4500</b> are a plurality of host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>(e.g., third computing devices) that are in communication, over a network <b>150</b>′, with the first protocol service <b>4502</b> and, through the first protocol service <b>4502</b> and over the network <b>150</b>, with the client machine <b>10</b>. Alternatively, in another embodiment, and with reference now to <figref idref="DRAWINGS">FIG. 46</figref>, the first protocol service <b>4502</b> and the host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>are not implemented as separate computing devices, as shown in <figref idref="DRAWINGS">FIG. 45</figref>, but, rather, they are incorporated into the same computing device, such as, for example, a remote machine <b>30</b>. The system <b>4500</b> can include one, two, or any number of remote machines <b>30</b>, <b>30</b>′. The protocol service <b>4502</b> may also be provided as a remote machine <b>30</b>.

0881In one embodiment, the networks <b>150</b> and <b>150</b>′ are separate networks, as in <figref idref="DRAWINGS">FIG. 45</figref>. The networks <b>150</b> and <b>150</b>′ can be the same network <b>150</b>, as shown in <figref idref="DRAWINGS">FIG. 46</figref>.

0882Referring still to the embodiments of <figref idref="DRAWINGS">FIGS. 45 and 46</figref>, the client machine <b>10</b> is configured to establish a connection <b>4504</b> between the client machine <b>10</b> and a first protocol service <b>4502</b> over the network <b>150</b> using a first protocol. For its part, the first protocol service <b>4502</b> is configured to accept the connection <b>4504</b>. The client machine <b>10</b> and the first protocol service <b>4502</b> can, therefore, communicate with one another using the first protocol as described below in reference to <figref idref="DRAWINGS">FIGS. 47-48</figref> and <figref idref="DRAWINGS">FIG. 49</figref>.

0883In some embodiments, as shown in <figref idref="DRAWINGS">FIGS. 45 and 46</figref>, a client agent <b>4506</b> is included within the client machine <b>10</b>. The client agent <b>4506</b> can be, for example, implemented as a software program and/or as a hardware device, such as, for example, an ASIC or an FPGA. The client agent <b>4506</b> can use any type of protocol and it can be, for example, an HTTP client agent, an FTP client agent, an Oscar client agent, a Telnet client agent, an Independent Computing Architecture (ICA) client agent from Citrix Systems, Inc. of Fort Lauderdale, Fla., or a Remote Desktop Procedure (RDP) client agent from Microsoft Corporation of Redmond, Wash. In some embodiments, the client agent <b>4506</b> is itself configured to communicate using the first protocol. In some embodiments (not shown), the client machine <b>10</b> includes a plurality of client agents <b>4506</b><i>a</i>-<b>4506</b><i>n</i>, each of which communicates with a host service <b>4516</b><i>a</i>-<b>4516</b><i>n</i>, respectively.

0884In another embodiment, a standalone client agent is configured to enable the client machine <b>10</b> to communicate using the first protocol. The standalone client agent can be incorporated within the client machine <b>10</b> or, alternatively, the standalone client agent can be separate from the client machine <b>10</b>. The standalone client agent is, for example, a local host proxy. In general, the standalone client agent can implement any of the functions described herein with respect to the client agent <b>4506</b>.

0885As also described further below, the first protocol service <b>4502</b> is, in one embodiment, itself configured to communicate using the first protocol. The first protocol service <b>4502</b> is configured to establish a connection <b>4508</b><i>a</i>-<b>4508</b><i>n </i>between the first protocol service <b>4502</b> and the host service <b>4516</b><i>a</i>-<b>4516</b><i>n</i>, respectively. For example, the first protocol service <b>4502</b> can establish a connection <b>4508</b><i>a </i>between the first protocol service <b>4502</b> and one host service <b>4516</b><i>a </i>and a connection <b>4508</b><i>b </i>between the first protocol service <b>4502</b> and another host service <b>4516</b><i>b</i>. In one embodiment, the first protocol service <b>108</b> separately establishes such connections <b>4508</b><i>a</i>-<b>4508</b><i>n </i>(i.e., the first protocol service <b>4502</b> establishes one connection at a time). In another embodiment, the first protocol service <b>4502</b> simultaneously establishes two or more of such connections <b>4508</b><i>a</i>-<b>4508</b><i>n. </i>

0886In yet another embodiment, the first protocol service <b>4502</b> can concurrently establish and maintain multiple connections <b>4508</b><i>a</i>-<b>4508</b><i>n</i>. The first protocol service <b>4502</b> is configured to provide two or more connections <b>4508</b><i>a</i>-<b>4508</b><i>n </i>without interrupting the connection <b>4504</b> with the client machine <b>10</b>. For example, the first protocol service <b>4502</b> can be configured to establish the connection <b>4508</b><i>a </i>between the first protocol service <b>4502</b> and the host service <b>4516</b><i>a </i>when a user of the client machine <b>10</b> requests execution of a first application program residing on the host service <b>4516</b><i>a</i>. When the user ends execution of the first application program and initiates execution of a second application program residing, for example, on the host service <b>4516</b><i>b</i>, the first protocol service <b>4502</b> is, in one embodiment, configured to interrupt the connection <b>4508</b><i>a </i>and establish the connection <b>4508</b><i>b </i>between the first protocol service <b>4502</b> and the host service <b>4516</b><i>b</i>, without disrupting the connection <b>4504</b> between the first protocol service <b>4502</b> and the client machine <b>10</b>.

0887The first protocol service <b>4502</b> and the host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>can communicate over the connections <b>4508</b><i>a</i>-<b>4508</b><i>n</i>, respectively, using any one of a variety of secondary protocols, including, but not limited to, HTTP, FTP, Oscar, Telnet, the ICA remote display protocol from Citrix Systems, Inc. of Fort Lauderdale, Fla., and/or the RDP remote display protocol from Microsoft Corporation of Redmond, Wash. For example, the first protocol service <b>4502</b> and the host service <b>4516</b><i>a </i>can communicate over the connection <b>4508</b><i>a </i>using the ICA remote display protocol, while the first protocol service <b>4502</b> and the host service <b>4516</b><i>b </i>can communicate over the connection <b>4508</b><i>b </i>using the RDP remote display protocol.

0888In one embodiment, the secondary protocol used for communicating between the first protocol service <b>4502</b> and a host service <b>4516</b>, such as, for example, the ICA remote display protocol, includes a plurality of virtual channels. A virtual channel is a session-oriented transmission connection that is used by application-layer code to issue commands for exchanging data. For example, each of the plurality of virtual channels can include a plurality of protocol packets that enable functionality at the remote client machine <b>10</b>. In one embodiment, one of the plurality of virtual channels includes protocol packets for transmitting graphical screen commands from a host service <b>4516</b>, through the first protocol service <b>4502</b>, to the client machine <b>10</b>, for causing the client machine <b>10</b> to display a graphical user interface. In another embodiment, one of the plurality of virtual channels includes protocol packets for transmitting printer commands from a host service <b>4516</b>, through the first protocol service <b>4502</b>, to the client machine <b>10</b>, for causing a document to be printed at the client machine <b>10</b>.

0889In another embodiment, the first protocol is a tunneling protocol. The first protocol service <b>4502</b> encapsulates a plurality of secondary protocols, each used for communication between one of the host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>and the first protocol service <b>4502</b>, within the first protocol. As such, the host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>and the first protocol service <b>4502</b> communicate with the client machine <b>10</b> via the plurality of secondary protocols. In one embodiment, the first protocol is, for example, an application-level transport protocol, capable of tunneling the multiple secondary protocols over a TCP/IP connection.

0890Referring to <figref idref="DRAWINGS">FIG. 47</figref>, communications between the client machine <b>10</b> and the first protocol service <b>4502</b> via the connection <b>4504</b> take the form of a plurality of secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n </i>(e.g., HTTP, FTP, Oscar, Telnet, ICA, and/or RDP) encapsulated within a first protocol <b>4704</b>. This is indicated by the location of secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n </i>inside the first protocol <b>4704</b>. Where secure communication is not called for, the first protocol <b>4704</b> can be, as illustrated in <figref idref="DRAWINGS">FIG. 47</figref>, communicated over an unsecured TCP/IP connection <b>4706</b>.

0891Referring now to <figref idref="DRAWINGS">FIG. 48</figref>, if secure communication is used, the first protocol <b>4704</b> is communicated over an encrypted connection, such as, for example, a TCP/IP connection <b>4802</b> secured by using a secure protocol <b>4804</b> such as the Secure Socket Layer (SSL). SSL is a secure protocol first developed by Netscape Communication Corporation of Mountain View, Calif., and is now a standard promulgated by the Internet Engineering Task Force (IETF) as the Transport Layer Security (TLS) protocol and described in IETF RFC-2246.

0892Thus, the plurality of secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n </i>are communicated within the first protocol <b>4704</b> with (<figref idref="DRAWINGS">FIG. 48</figref>) or without (<figref idref="DRAWINGS">FIG. 47</figref>) a secure protocol <b>4804</b> over the connection <b>4504</b>. The secondary protocols that can be used to communicate over the connections <b>4508</b><i>a</i>-<b>4508</b><i>n </i>include, but are not limited to, HTTP, FTP, Oscar, Telnet, ICA, and RDP. Moreover, in one embodiment, at least one of the secondary protocols, as described above, includes a plurality of virtual channels, each of which can include a plurality of protocol packets enabling functionality at the remote client machine <b>10</b>. For example, in one embodiment, one host service <b>4516</b><i>a </i>is a web server, communicating with the first protocol service <b>4502</b> over the connection <b>4508</b><i>a </i>using the HTTP protocol, and another host service <b>4516</b><i>b </i>is an application server, communicating with the first protocol service <b>4502</b> over the connection <b>4508</b><i>b </i>using the ICA protocol. The host service <b>4516</b><i>b </i>generates both protocol packets for transmitting graphical screen commands to the client machine <b>10</b>, for causing the client machine <b>10</b> to display a graphical user interface, and protocol packets for transmitting printer commands to the client machine <b>10</b>, for causing a document to be printed at the client machine <b>10</b>.

0893In another embodiment, the method and systems described herein reduce the number of times network connections are opened and closed. In one embodiment, the first protocol <b>4704</b> allows the secondary protocol connections <b>4702</b><i>a</i>-<b>4702</b><i>n </i>tunneled therein, such as, for example, an HTTP connection <b>4702</b><i>n</i>, to be opened and/or closed, repetitively, without also requiring the transport connection over which the first protocol <b>4704</b> is communicated (e.g., TCP connection <b>4706</b> and/or <b>4802</b>), the secure protocol connection <b>4804</b>, or the first protocol connection <b>4704</b> itself to similarly be repetitively opened and/or closed. Without the encapsulation of the first protocol <b>4704</b>, the secondary protocol <b>4702</b><i>a</i>-<b>4702</b><i>n </i>may frequently open and close network connections, such as TCP connections. This would add significant delays and overhead to the system. These delays and overhead would be further increased by the use of a secure encapsulation protocol <b>4806</b>, such as SSL, which have significant overhead in establishing network connections. By encapsulating the secondary protocol <b>4702</b><i>a</i>-<b>4702</b><i>n </i>within the first protocol <b>4704</b> and maintaining the connection of the transport connection (<b>4706</b>, <b>4802</b>), the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n</i>, as part of the payload of the first protocol <b>4704</b>, do not need to perform frequent and costly open and closes of the network connection <b>4504</b>. Furthermore, since the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n </i>can be communicated within the first protocol <b>4704</b> with a secure protocol <b>4804</b>, the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n </i>also do not need to open and close secured connections such as with SSL. The transport connection (<b>4706</b>, <b>4802</b>) establishes and maintains the network connection <b>4504</b> so that the encapsulated second protocols <b>4702</b><i>a</i>-<b>4702</b><i>n </i>can be communicated without repetitively opening and closing the secured or unsecured network connection <b>4504</b>. This significantly increases the speed of operation in communicating the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n. </i>

0894As described above, the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n </i>carry protocol packets related to applications using such protocols as HTTP, FTP, Oscar, Telnet, RDA or ICA. The secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n </i>transport data related to the application functionality transacted between the client machine <b>10</b> and the host service <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. For example, a user on the client machine <b>10</b> may interact with a web page provided by a host service <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. In transactions between the client machine <b>10</b> and the host service <b>4516</b><i>a</i>-<b>4516</b><i>n</i>, the secondary protocol <b>4702</b><i>a</i>-<b>4702</b><i>n </i>encapsulated in the first protocol <b>4704</b> may have http protocol packets related to displaying the web page and receiving any user interaction to communicate to the host service <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. Since the transport connection (<b>4706</b>, <b>4802</b>) is not maintained by the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n</i>, the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n </i>do not need to handle any network-level connection interruptions. As such, the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n </i>may not provide any network-level connection interruption information in their payloads. In the above example, the http related secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n </i>of the secondary protocol <b>4702</b><i>a</i>-<b>4702</b><i>n </i>transmitted to the client machine <b>10</b> would not provide a notification that a network interruption occurred, e.g., an error message on a web page. Therefore, the user on the client machine <b>10</b> will not be notified of any network-level connection interrupts through the secondary protocol <b>4702</b><i>a</i>-<b>4702</b><i>n</i>. This effectively hides the network connection interruptions from the user during the use of the applications related to the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n. </i>

0895Referring to <figref idref="DRAWINGS">FIG. 49</figref>, an example process <b>4900</b> used by the first protocol service <b>4502</b> and the client agent <b>4506</b> of the client machine <b>10</b> encapsulates the plurality of secondary protocols <b>4702</b> (e.g., HTTP, FTP, Oscar, Telnet, ICA, and/or RDP) within the first protocol <b>4704</b> for communication via the connection <b>4504</b>. Optionally, as described below, the example process <b>4900</b> used by the first protocol service <b>4502</b> and the client agent <b>4506</b> of the client machine <b>10</b> also compresses and/or encrypts the communications at the level of the first protocol prior to communications via the connection <b>4504</b>. From the point of view of the first protocol service <b>4502</b>, secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n </i>are received via the connections <b>4508</b><i>a</i>-<b>4508</b><i>n </i>at the first protocol service <b>4502</b>. For example, two secondary protocol packets <b>4902</b><i>a </i>and <b>4902</b><i>b </i>are received by the first protocol service <b>4502</b>. One, two, or any number of secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n </i>can be received. In one embodiment, the secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n </i>are transmitted by the host services <b>4516</b> to the first protocol service <b>4502</b> over the connection <b>4508</b>. The secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n </i>include a header <b>4904</b> and a data packet <b>4906</b>, also referred to as a data payload.

0896Following receipt of the secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n</i>, the first protocol service <b>4502</b> encapsulates one or more of the secondary protocol packets <b>4902</b> within a first protocol packet <b>4908</b>. In one embodiment, the first protocol service <b>4502</b> generates a first protocol packet header <b>4910</b> and encapsulates within the data payload <b>4912</b> of the first protocol packet <b>4908</b> one or more secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n</i>, such as, for example, two secondary protocol packets <b>4902</b><i>a </i>and <b>4902</b><i>b</i>. In another embodiment, only one secondary protocol packet <b>4902</b><i>a </i>is encapsulated in each first protocol packet <b>4908</b>.

0897In one embodiment, the first protocol packets <b>4908</b> are then transmitted over the connection <b>4504</b>, for example over the connection <b>4706</b> described with reference to <figref idref="DRAWINGS">FIG. 47</figref>, to the client agent <b>4506</b> of the client machine <b>10</b>. Alternatively, in another embodiment, the first protocol service <b>4502</b> is further configured to encrypt, prior to the transmission of any first protocol packets <b>4908</b>, communications at the level of the first protocol <b>4704</b>. In one such embodiment, the first protocol packets <b>4908</b> are encrypted by using, for example, the SSL protocol described with reference to <figref idref="DRAWINGS">FIG. 48</figref>. As a result, a secure packet <b>4914</b>, including a header <b>4916</b> and an encrypted first protocol packet <b>4908</b>′ as a data payload <b>4918</b>, is generated. The secure packet <b>4914</b> can then be transmitted over the connection <b>4504</b>, for example over the secure TCP/IP connection <b>4802</b> illustrated in <figref idref="DRAWINGS">FIG. 48</figref>, to the client agent <b>4506</b> of the client machine <b>10</b>.

0898In another embodiment, the first protocol service <b>4502</b> is further configured to compress, prior to the transmission of any first protocol packets <b>4908</b>, communications at the level of the first protocol <b>4704</b>. In one embodiment, prior to encrypting the first protocol packet <b>4908</b>, the first protocol service <b>4502</b> compresses, using a standard compression technique, the first protocol packet <b>4908</b>. As such, the efficiency of the system <b>4502</b> is improved.

0899Referring again to <figref idref="DRAWINGS">FIGS. 45-46</figref>, in one embodiment, the system <b>4500</b> provides the remote client machine <b>10</b> with a persistent connection to a remote machine <b>30</b>, such as, for example, the remote machine <b>30</b>′. For example, if the client machine <b>10</b> establishes a connection <b>4504</b> between the client machine <b>10</b> and the first protocol service <b>4502</b> and the first protocol service <b>4502</b> establishes a connection <b>4508</b><i>a </i>between the first protocol service <b>4502</b> and the remote machine <b>30</b>′, then either the client agent <b>4506</b>, the first protocol service <b>4502</b>, or both are configured to maintain a queue of the first protocol data packets most recently transmitted via the connection <b>4504</b>. For example, the queued data packets can be maintained by the client agent <b>4506</b> and/or the first protocol service <b>4502</b> both before and upon a failure of the connection <b>4504</b>. Moreover, upon a failure of the connection <b>4504</b>, the first protocol service <b>4502</b> and, likewise, the remote machine <b>30</b> are configured to maintain the connection <b>4508</b><i>a. </i>

0900Following a failure of the connection <b>4504</b>, the client machine <b>10</b> establishes a new connection <b>4504</b> with the first protocol service <b>4502</b>, without losing any data. More specifically, because the connection <b>4508</b><i>a </i>is maintained upon a failure of the connection <b>4504</b>, a newly established connection <b>4504</b> can be linked to the maintained connection <b>4508</b><i>a</i>. Further, because the most recently transmitted first protocol data packets are queued, they can again be transmitted by the client machine <b>10</b> to the first protocol service <b>4502</b> and/or by the first protocol service <b>4502</b> to the client machine <b>10</b> over the newly established connection <b>4504</b>. As such, the communication session between the remote machine <b>30</b>′ and the client machine <b>10</b>, through the first protocol service <b>4502</b>, is persistent and proceeds without any loss of data.

0901In one embodiment, the client agent <b>4506</b> of the client machine <b>10</b> and/or the first protocol service <b>4502</b> number the data packets that they transmit over the connection <b>4504</b>. For example, each of the client agent <b>4506</b> and the first protocol service <b>4502</b> separately numbers its own transmitted data packets, without regard to how the other is numbering its data packets. Moreover, the numbering of the data packets can be absolute, without any re-numbering of the data packets, i.e., the first data packet transmitted by the client agent <b>4506</b> and/or the first protocol service <b>4502</b> can be numbered as No. 1, with each data packet transmitted over the connection <b>4504</b> by the client agent <b>4506</b> and/or the first protocol service <b>4502</b>, respectively, consecutively numbered thereafter.

0902In one such embodiment, following a disrupted and re-established connection <b>4504</b>, the client agent <b>4506</b> and/or the first protocol service <b>4502</b> informs the other of the next data packet that it requires. For example, where the client agent <b>4506</b> had received data packets Nos. 1-10 prior to the disruption of connection <b>4504</b>, the client agent <b>4506</b>, upon re-establishment of the connection <b>4504</b>, informs the first protocol service <b>4502</b> that it now requires data packet No. 11. Similarly, the first protocol service <b>4502</b> can also operate as such. Alternatively, in another such embodiment, the client agent <b>4506</b> and/or the first protocol service <b>4502</b> informs the other of the last data packet received. For example, where the client agent <b>4506</b> had received data packets Nos. 1-10 prior to the disruption of connection <b>4504</b>, the client agent <b>4506</b>, upon reestablishment of the connection <b>4504</b>, informs the first protocol service <b>4502</b> that it last received data packet No. 10. Again, the first protocol service <b>4502</b> can also operate as such. In yet another embodiment, the client agent <b>4506</b> and/or the first protocol service <b>4502</b> informs the other, upon re-establishment of the connection <b>4504</b>, of both the last data packet received and the next data packet it requires.

0903In such embodiments, upon re-establishment of the connection <b>4504</b>, the client agent <b>4506</b> and/or the first protocol service <b>4502</b> can retransmit the buffered data packets not received by the other, allowing the communication session between a host service <b>4516</b> and the client machine <b>10</b>, through the first protocol service <b>4502</b>, to proceed without any loss of data. Moreover, upon reestablishment of the connection <b>4504</b>, the client agent <b>4506</b> and/or the first protocol service <b>4502</b> can flush from each of their respective buffers the buffered data packets now known to be received by the other.

0904By providing the client machine <b>10</b> with a reliable and persistent connection to a remote machine <b>30</b>, the process of opening a new user session with the remote machine <b>30</b> is avoided by maintaining the user session through network connection interruptions. For each user session with a remote machine <b>30</b>, the client machine <b>10</b> and the remote machine <b>30</b> may maintain session specific context and caches, and other application specific mechanisms related to that instance of the user session. For each new user session established, these session-specific context and caches need to be re-populated or reestablished to reflect the new user session. For example, a user on the client machine <b>10</b> may have an http session with a remote machine <b>30</b>. The remote machine <b>30</b> may keep context-specific information of this instance of the http session with the client machine <b>10</b>. The context may be stored in the memory of the server, in files of the server, a database or other component related to providing the functionality of the remote machine <b>30</b>. Also, the client machine <b>10</b> may have local context specific to the instance of the http session, such as a mechanism for keeping track of an outstanding request to the remote machine <b>30</b>. This context may be stored in memory of the client machine <b>10</b>, in files on the client machine <b>10</b>, or other software component interfaced with the client machine <b>10</b>. If the connection between the client machine <b>10</b> and the remote machine <b>30</b> is not persistent, then a new user session needs to be established with new session specific context on the remote machine <b>30</b> and the client machine <b>10</b>. The session is maintained so that a new session, and therefore new specific session context, does not need to be re-established.

0905In some embodiments, the user session is maintained through network level connection interruptions and without notification to the user of the client that the session was interrupted. In operation of these embodiments, the first protocol service <b>4502</b> establishes and maintains a first connection with a client machine <b>10</b> and a second connection with a host service <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. Via the first connection and the second connection, a session between the client machine <b>10</b> and the remote machine <b>30</b> is established. The first protocol service <b>4502</b> can store and maintain any session-related information such as authentication credentials, and client machine <b>10</b> and remote machine <b>30</b> context for the established session. A user on the client machine <b>10</b> will exercise the functionality provided by the remote machine <b>30</b> through the established session. As such, related secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n </i>will contain data related to the transaction of such functionality. These secondary protocol packets <b>4902</b><i>a</i>-<b>4902</b><i>n </i>as part of the secondary protocol <b>4702</b><i>a</i>-<b>4702</b><i>n </i>are encapsulated and communicated in a first protocol <b>4704</b>. Upon detection of a disruption in either the first connection or the second connection, the first protocol service <b>4502</b> can re-establish the disrupted connection while maintaining the other connection that may have not been disrupted. The network connection disruption may cause an interruption to the session between the client machine <b>10</b> and the remote machine <b>30</b>. However, since the transport mechanism is not maintained by the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n</i>, the session can be re-established after the network connection is re-established without the user on the client machine <b>10</b> having notification that the session was interrupted. The secondary protocol <b>4702</b><i>a</i>-<b>4702</b><i>n </i>does not need to contain any interruption related information to transmit to the client machine <b>10</b>. Thus, the interruption of the session caused by the network connection disruption is effectively hidden from the user because of the encapsulation of the first protocol <b>4704</b>.

0906The first protocol service <b>4502</b> maintaining session related information can re-establish the session between the client machine <b>10</b> and the remote machines <b>30</b>. For example, if the first connection between the client machine <b>10</b> and the first protocol service <b>4516</b> is disrupted, the first protocol service <b>4502</b> can keep the client machine <b>10</b>'s session active or open between the first protocol service <b>4502</b> and the remote machine <b>30</b>. After the first connection is re-established, the first protocol service <b>4502</b> can link the session of the client machine <b>10</b> to the maintained session between the first protocol service <b>4502</b> and the host service <b>4516</b>. The first protocol service <b>4502</b> can send to the client machine <b>10</b> any data that was queued prior to the disruption in the first connection. As such, the client machine <b>10</b> will be using the same session prior to the disruption, and the remote machine <b>30</b> and client machine <b>10</b> can continue to use any session specific context that may have in memory or stored elsewhere. Furthermore, because of the intermediary of the first protocol service <b>4502</b>, the remote machine <b>30</b> may not be aware of the network disruption between the first protocol service <b>4502</b> and the client machine <b>10</b>.

0907In another example, if the second connection between the first protocol service <b>4502</b> and the remote machine <b>30</b> is disrupted, the first protocol service can maintain the first connection with the client machine <b>10</b> while re-establishing the second connection with the remote machine <b>30</b>. After re-establishing the second connection, the first protocol service <b>4502</b> can re-establish the client's session, on behalf of the client, with the remote machine <b>30</b>. Since the first protocol service <b>4502</b> was maintaining any session relation information, the first protocol service may re-establish the same session or a similar session so that the client machine <b>10</b> is not aware of the disruption in the second network connection and the resulting disruption to the session between the first protocol service <b>4502</b> and the remote machine <b>30</b>. During re-establishing the second network connection and the session, the first protocol service <b>4502</b> can queue any session transactions sent by the client machine <b>10</b> during the disruption. Then, after re-establishing the session with the remote machine <b>30</b>, the first protocol service <b>4502</b> can transmit the queued transactions to the remote machine <b>30</b> and the session can continue normally. In this manner, the client machine <b>10</b> continues to operate as if there was not an interruption to the session.

0908Additionally, by providing a reliable and persistent connection, some embodiments also avoid interruptions to transactions, commands or operations as part of the functionality exercised between the client machine <b>10</b> and a remote machine <b>30</b>, or a remote machine <b>30</b>. For example, a file copy operation using Windows Explorer has not been designed to continue working after there is a disruption in a network connection. A user on the client machine <b>10</b> may use the file copy feature of Windows Explorer to copy a file from the client machine <b>10</b> to a remote machine <b>30</b>. Because of the size of the file or files, this operation may take a relatively extended period of time to complete. If during the middle of the operation of the copy of the file to the remote machine <b>30</b>, there is an interruption in the network connection between the client machine <b>10</b> and the remote machine <b>30</b>, the file copy will fail. Once the network connection is re-established, the user will need to start another file copy operation from Windows Explorer to copy the file from the client machine <b>10</b> to the remote machine <b>30</b>. Under some embodiments of the methods described above, the user would not need to start another file copy operation. The network connection would be re-established as part of the first protocol <b>4704</b> connection. The file copy operations would be encapsulated in the payload of the secondary protocols <b>4702</b><i>a</i>-<b>4702</b><i>n</i>. As such, the file copy of Windows Explorer would not get notified of the interruption in the network connection and therefore, would not fail. The first protocol service <b>4502</b> would re-establish any connections and transmits any queued data so that operation can continue without failure. The first protocol service <b>4502</b> would maintain a queue of the data related to the file copy operations that has not been transferred to the remote machine <b>30</b> because of the interruption in the network connection. Once the network connection is re-established, the first protocol service <b>4502</b> can transmit the queued data and then continue on with transferring the data related to the file copy operation in due course.

0909Although these embodiments are described in terms of a file copy operation example, one ordinarily skilled in the art will recognize that any operation, transaction, command, function call, etc. transacted between the client machine <b>10</b> and the remote machine <b>30</b>, or remote machines <b>30</b>, can be maintained and continued without failure from the network connection disruption, and, furthermore, without the client machine <b>10</b> recognizing there was a disruption or having notice of the disruption.

0910Furthermore, by providing a reliable and persistent connection, a client machine <b>10</b> is able to traverse through different network topologies without restarting a session or an application on the client machine <b>10</b>. For example, the client machine <b>10</b> may be a computer notebook with a wireless network connection. As the client machine <b>10</b> moves from a first wireless network to a second wireless network, the client's network connection <b>4504</b> may be temporarily disrupted from the first wireless network as a network connection is established with the second wireless network. The second wireless network may assign a new network identifier, such as a host name or internet protocol address, to the client machine <b>10</b>. This new network identifier may be different than the network identifier assigned to the client machine <b>10</b> by the first wireless network. In another example, the client machine <b>10</b> may be physically connected through an Ethernet cable to a port on the network. The physical connection may be unplugged and the client machine <b>10</b> moved to another location to plug into a different port on the network. This would cause a disruption into the network connection <b>102</b> and possible a change in the assigned network identifier. By the method and systems described herein, the network connection is maintained for the client and automatically re-established the network connection of the client machine <b>10</b>, including handling changes in the network topology and network identifier. The client machine <b>10</b>, and any applications or sessions on the client machine <b>10</b>, can continue to operate as if there was not a network connection disruption or a change in the network identifier. Furthermore, the user on the client machine <b>10</b> may not recognize there were any interruptions or changes, and the client machine <b>10</b> may not receive any notice of such interruptions.

0911Even with a reliable and persistent communication session as described above, network connections are still disrupted. When re-establishing the client's connection to the host service, the client machine <b>10</b> also needs to be re-authenticated to the remote machine <b>30</b>. In one embodiment, systems and methods authenticate a client machine <b>10</b> to a host service <b>4516</b> and re-authenticate the client machine <b>10</b> to the remote machine <b>30</b> without re-entering authentication credentials.

0912In another embodiment, securely establishing a communication session between the client machine <b>10</b> and the host service <b>4516</b> is enabled via multiple connections or “hops” that traverse multiple network components, such as a proxy, security gateway, firewall or router. The establishment of the multiple hop secure communication session may further be initiated via a secure client-web server communication channel, for example, between the web browser <b>6302</b> and a first remote machine <b>30</b> using SSL. The ticket authority <b>6102</b> can provide tickets for each of the hops such as the client-first protocol service connection <b>4504</b> and the first protocol service to host service connections <b>4508</b><i>a</i>-<b>4508</b><i>n</i>. In this manner, the client machine <b>10</b> is authenticated through all the connections between the client machine <b>10</b> and the host service <b>4516</b><i>a</i>-<b>45116</b><i>n. </i>

0913In some embodiments, a first remote machine <b>30</b>, functioning as a web server, receives a request from the client machine <b>10</b> for an application and the first remote machine <b>30</b> validates the request with the ticket authority <b>6102</b>. The ticket authority <b>6102</b> then generates an N part ticket (e.g., T₁to T_N). In one embodiment, the ticket authority <b>6102</b> then transmits a portion T_iof the N part ticket (e.g., the first part of the ticket, or first ticket T₁) to the first remote machine <b>30</b>. The first remote machine <b>30</b> then transmits the ticket T₁to the client machine <b>10</b>. In one embodiment, the ticket authority <b>6102</b> also transmits the address of the next “hop” (e.g., the first protocol service <b>4502</b> to the first remote machine <b>30</b>, which then transmits the address to the client machine <b>10</b>. This address is the address of the next hop (e.g., first protocol service <b>4502</b>) that this hop (e.g., client machine <b>10</b>) needs to communicate with for the client machine <b>10</b> to eventually be authenticated to the remote machine <b>30</b>.

0914The client machine <b>10</b> uses the address to then contact the next “hop” (e.g., first protocol service <b>4502</b>) and initiates a communication session with the first protocol service <b>4502</b><i>a </i>by transmitting a proxy connection request over the client-first protocol service communication channel <b>4504</b>. The first protocol service <b>4502</b><i>a </i>then extracts the first ticket T₁from the proxy connection request and forwards this ticket to the ticket authority <b>6102</b> for validation. The ticket authority <b>6102</b> then validates the first ticket T₁.

0915Upon proper verification of the first ticket T₁, the ticket authority <b>6102</b> transmits the next ticket T_ifrom the N part ticket (e.g., T₂) to the next first protocol service <b>4502</b> (e.g., first protocol service <b>4502</b><i>a</i>). In some embodiments, the ticket authority <b>6102</b> also transmits the address of the next hop (e.g., the second first protocol service <b>4502</b><i>b</i>) to this hop (e.g., the first protocol service <b>4502</b><i>a</i>). The first protocol service <b>4502</b><i>a </i>transmits this ticket to the next hop (e.g., the second first protocol service <b>4502</b><i>b</i>). In one embodiment, the second first protocol service <b>4502</b><i>b </i>verifies T₂by transmitting the ticket to the ticket authority <b>6102</b>. The ticket authority <b>6102</b> validates the second ticket T₂and the process continues. Once the last part of the N part ticket has been validated the application is launched on the client machine <b>10</b>.

0916In one embodiment, each first protocol service <b>4502</b> (i.e., each hop) validates T_i(e.g., T₂) with a ticket authority <b>6102</b> associated with the first protocol service <b>4502</b> (i.e., hop). In this embodiment, after each first protocol service <b>4502</b> validates the ticket T_i(e.g., T₂) with a ticket authority <b>6102</b>, the ticket authority <b>6102</b> at which the validation took place transmits the next ticket T_i+1(e.g., T₃) and the address of the next first protocol service <b>4502</b> (i.e., the next “hop” destination) to the first protocol service <b>4502</b> that had validated the ticket T_i. Thus, each first protocol service <b>4502</b> is associated with a ticket authority <b>6102</b> that has been configured with the current and next hop tickets (i.e., validating T_iand transmitting T_i+1for the next hop). Consequently, the next first protocol service <b>4502</b> acts as the client for that hop. This process is repeated until reaching the remote machine <b>30</b>. Thus, each hop has been validated individually without revealing all of the ticket to any one hop.

0917In other embodiments, the ticket authority <b>6102</b> may issue more than one ticket rather than issuing one ticket having many parts. For example, the ticket authority <b>6102</b> generates a first hop ticket and a second hop ticket, where the first hop ticket has no association with the second hop ticket. The ticket authority <b>6102</b> subsequently transmits the first hop ticket to the first remote machine <b>30</b> and the first remote machine <b>30</b> transmits the first hop ticket to the client machine <b>10</b>. The client machine <b>10</b> transmits this first hop ticket to the first protocol service <b>4502</b> (e.g., first protocol service <b>4502</b><i>a</i>) for validation by the ticket authority <b>6102</b>. Upon validation, the ticket authority <b>6102</b> transmits the second hop ticket to the next first protocol service <b>4502</b> (e.g., second first protocol service <b>4502</b><i>b</i>) while the first hop ticket is independent from the second hop ticket.

0918In a further embodiment, one or more of the ticket authorities <b>6102</b> provides proxies, either as part of the first protocol service <b>4502</b> or separated from the first protocol service <b>4502</b>, with any necessary information needed to connect to the next hop, such as, but without limitation, encryption keys, SSL method configuration information, and authentication information to connect to a SOCKS server (e.g., SOCKS5 server, developed by NEC Corporation of Tokyo, Japan).

0919In yet another embodiment, a ticket authority <b>6102</b> only generates a single ticket. The ticket authority <b>6102</b> transmits the single ticket to the first remote machine <b>30</b>. The first remote machine <b>30</b> forwards the single ticket to the client machine <b>10</b>. The first protocol service <b>4502</b> subsequently receives the ticket from the client machine <b>10</b> and “consumes” the single ticket upon validation. As a result, a single ticket can provide the ability to use arbitrary communication protocols over the client-proxy communication channel <b>4504</b> and the client-web server communication channel. Additionally, because the remote machine <b>30</b> does not receive or verify the single ticket, the ticket is transparent to the remote machine <b>30</b> and, consequently, the remote machine <b>30</b> is not “aware” of the use of the ticket.

0920By exploiting the security of the secure communications between the client machine <b>10</b> and the first remote machine <b>30</b> over the secure client-web server communication channel, the system establishes a secure communication link over the non-secure client-proxy communication channel <b>4504</b> to remotely display desktop applications securely on the client machine <b>10</b>.

0921In yet another embodiment, the ticket authority <b>6102</b> transmits a disabled version of the first protocol service ticket with the client ticket to the first remote machine <b>30</b> for transmission to the client machine <b>10</b>. The client machine <b>10</b> subsequently transmits the first protocol service ticket along with the client ticket to the first protocol service <b>4502</b> as part of the proxy connection request. The first protocol service <b>4502</b> then forwards both tickets to the ticket authority <b>6102</b>. Upon receiving a disabled first protocol service ticket, the ticket authority <b>6102</b> enables the first protocol service ticket after validating the client ticket. The ticket authority <b>6102</b> then transmits the enabled first protocol service ticket to the first protocol service <b>4502</b> for authentication to the host node <b>118</b>.

0922Alternatively, in another embodiment the first remote machine <b>30</b> receives a disabled first protocol service ticket and an enabled client ticket from the ticket authority <b>6102</b> and only transmits the client ticket to the client machine <b>10</b>. The client machine <b>10</b> transmits the client ticket to the first protocol service <b>4502</b> as part of the proxy connection request. The first protocol service <b>4502</b> then forwards the client ticket to the ticket authority <b>6102</b>. The ticket authority <b>6102</b> validates the client ticket and, upon validation, enables the first protocol service ticket previously transmitted to the first remote machine <b>30</b>. In yet another embodiment, the ticket authority <b>6102</b> transmits an enabled first protocol service ticket to the first remote machine <b>30</b> upon validation of the client ticket for authentication to the remote machine <b>30</b>.

0923Thus, at any given time, the ticket authority <b>6102</b> provides only one ticket that is enabled to the client machine <b>10</b> or first protocol service <b>4502</b> that the ticket authority <b>6102</b> can validate. The ticket authority <b>6102</b> may provide another ticket that can't be validated (i.e., a disabled ticket) until the enabled ticket is validated. Alternatively, the ticket authority <b>6102</b> may not transmit the first protocol service ticket to the first protocol service <b>4502</b> until the ticket authority <b>6102</b> validates the enabled ticket. As discussed in further detail below, this enforces network routing of communications using embodiments of this system because the client machine <b>10</b> cannot traverse the first remote machine <b>30</b> or the first protocol service <b>4502</b> without having the ticket authority <b>6102</b> validate the enabled ticket and transmit the ticket needed to communicate with the remote machine <b>30</b>.

0924In another embodiment, instead of transmitting the first protocol service ticket to the first protocol service <b>4502</b>, the ticket authority <b>6102</b> transmits the first protocol service ticket to the first remote machine <b>30</b> directly over a web server-authority communication channel. The first remote machine <b>30</b> then automatically transmits the first protocol service ticket to the remote machine <b>30</b>. In other words, the first remote machine <b>30</b> “pushes” the first protocol service ticket to the remote machine <b>30</b>. The ticket authority <b>6102</b> can also push the first protocol service ticket to the remote machine <b>30</b> without transmission of the first protocol service ticket to the first protocol service <b>4502</b> or the first remote machine <b>30</b>.

0925In yet another embodiment, the remote machine <b>30</b> retrieves the first protocol service ticket from the ticket authority <b>6102</b> over the ticket-content server communication channel <b>157</b>. In other words, the remote machine <b>30</b> “pulls” the first protocol service ticket from the ticket authority <b>6102</b>.

0926Moreover, the system enforces the routing of the client machine <b>10</b> through the first protocol service <b>4502</b>. As stated above, the client machine <b>10</b> has to possess the first protocol service ticket to establish a communication session with the remote machine <b>30</b>. More specifically, to establish a connection with the remote machine <b>30</b>, the first remote machine <b>30</b> first has to validate the request of the client machine <b>10</b> with the ticket authority <b>6102</b>. Once validated, the client machine <b>10</b> obtains the first ticket and transmits this first ticket to the ticket authority <b>6102</b> for validation. However, upon validation, the ticket authority <b>6102</b> transmits the first protocol service ticket back to the first protocol service <b>4502</b> rather than the client machine <b>10</b>. The communication session between the client machine <b>10</b> and the host service <b>4516</b> is established when the host service <b>4516</b> receives the first protocol service ticket. Thus, the client machine <b>10</b> has to communicate with the first protocol service <b>4502</b> in order to have the first protocol service ticket transmitted to the host service <b>4516</b>, thereby enforcing the routing of the client machine <b>10</b> through the first protocol service <b>4502</b>. Thus, the invention can ensure the proper traversal of a security device (e.g., the first protocol service <b>4502</b>) before granting access to the remote machine <b>30</b>.

0927For example, a remote machine <b>30</b> executes several applications, such as MICROSOFT WORD and MICROSOFT EXCEL, both developed by Microsoft Corporation of Redmond, Wash. In one embodiment, the client machine <b>10</b> uses NFUSE, developed by Citrix Systems, Inc. of Fort Lauderdale, Fla., to obtain information from the machine farm <b>38</b> in which applications can be accessed by the client machine <b>10</b>. If a client user wants to access and use MICROSOFT WORD, the client machine <b>10</b> requests the application from the first remote machine <b>30</b>. However, only users who pay an application fee for MICROSOFT WORD can become authorized to access the application.

0928To ensure the payment of the application fee, the system includes the first protocol service <b>4502</b> and the ticket authority <b>6102</b> to enforce the routing of the client machine <b>10</b> through the first protocol service <b>4502</b>. The routing of the client machine <b>10</b> through the first protocol service <b>4502</b> is valuable to the application provider if the first protocol service <b>4502</b> is used to collect the application fee and authorize the user for access to the application.

0929The ticket authority <b>6102</b> subsequently generates a ticket associated with the request for the application. An enabled first ticket is then transmitted to the client machine <b>10</b>. Because the client machine <b>10</b> does not have the address of the host node <b>118</b>, the client machine <b>10</b> cannot access the application. Further, the client machine <b>10</b> has not been authorized by the first protocol service <b>4502</b> yet (i.e., has not yet paid). Thus, the client machine <b>10</b> has to communicate with the first protocol service <b>4502</b> to become authorized. The first protocol service <b>4502</b> can then transmit the enabled first ticket to the ticket authority <b>6102</b> upon payment of the application fee.

0930The ticket authority then validates the client ticket and subsequently transmits (or enables) a first protocol service ticket to the proxy. The first protocol service <b>4502</b> then transmits the first protocol service ticket to the remote machine <b>30</b> (e.g., assuming the client user has paid the application fee), which enables the remote machine <b>30</b> to transmit the application to the client machine <b>10</b>.

0931<figref idref="DRAWINGS">FIG. 50</figref> depicts one embodiment of a system <b>5000</b> that is capable of reconnecting the client machine <b>10</b> to a host service <b>4516</b> using an automatic client reconnect service referred to as auto client reconnect service or ACR Service <b>5002</b>. In brief overview, a client machine <b>10</b> communicates with a remote machine <b>30</b>, also referred to as a server, over a communication channel <b>5004</b>. The communication channel <b>5004</b> may include a network <b>150</b>. For example, the communication channel <b>5004</b> can be over a local-area network (LAN), such as a company Intranet, or a wide area network (WAN) such as the Internet or the World Wide Web. The remote machine <b>30</b> provides auto client reconnect services through an ACR Service <b>5002</b>. The client machine <b>10</b> accesses the remote machine <b>30</b> through the communication channel <b>5004</b>. The ACR Service <b>5002</b> of the remote machine <b>30</b> provides authentication services to authenticate the client machine <b>10</b> to the remote machine <b>30</b>. When there is a disruption in a network connection, the ACR Service <b>5002</b> further provides re-authentication services to re-authenticate the client machine <b>10</b> to the remote machine <b>30</b>. Although described with a single client machine <b>10</b> and one communication channel <b>5004</b>, any number of clients (e.g. <b>10</b>, <b>10</b>′) and number of communication channels (e.g. <b>5004</b>, <b>5004</b>′) can be part of the system <b>4500</b>.

0932The ACR Service <b>5002</b> running on the remote machine <b>30</b> includes a key generator <b>5006</b>, a session identifier (SID) generator <b>5008</b>, an encryptor <b>5010</b>, a key destroyer <b>5012</b>, and a decryptor <b>5014</b>. The key generator <b>5006</b> generates a key when the remote machine <b>30</b> or the ACR Service <b>5002</b> receives authentication credentials from the client machine <b>10</b>. In one embodiment, the key generator <b>5006</b> derives the key from a characteristic of the remote machine <b>30</b>. Particular examples include the key generator <b>5006</b> deriving the key from the temperature of the processor <b>5016</b>, the time that remote machine <b>30</b> received the authentication credentials, and the number of keys stored in memory <b>5018</b>. In a further embodiment, the key and the authentication credentials are the same size (e.g. eight bits). In one embodiment, the key generator is a software module. In another embodiment, the key generator <b>5006</b> is a random number generator.

0933The SID generator <b>5008</b> generates the unique SID to enable the remote machine <b>30</b> to identify a particular communication session. In one embodiment, the SID generator <b>5008</b> is a software module. In another embodiment, the SID generator <b>5008</b> is a random number generator. In another embodiment, the SID generator transmits the SID to the host service <b>4516</b>. In one embodiment, the SID generator <b>5008</b> obtains the SID from a host service <b>4516</b> running on the server. In yet another embodiment, the SID generator generates the SID by receiving a session identifier from the host service <b>116</b> establishing a user session.

0934The encryptor <b>5010</b> encrypts the key with the authentication credentials to create encrypted authentication credentials. In one embodiment, the encryptor <b>5010</b> encrypts the key with the authentication credentials by performing an exclusive OR operation (i.e. XOR) on the key and the authentication credentials. In another embodiment, the encryptor <b>5010</b> adds the authentication credentials to the key to encrypt the authentication credentials; that is, the encryptor <b>5010</b> performs a “Caesar Cipher” on the authentication credentials using the key as the shift value. In another embodiment, the encryptor <b>5010</b> performs a hash function, such as MD4, MD5, or SHA-1, on the authentication credentials. It should be clear that the encryptor <b>5010</b> can perform any type of manipulation on the authentication credentials as long as the ACR Service <b>5002</b> can decrypt the encrypted authentication credentials with the key.

0935In one embodiment, the encryptor <b>5010</b> is a software module that executes mathematical algorithms on the key and the authentication credentials to create the encrypted authentication credentials. In another embodiment, the encryptor <b>5010</b> is a logic gate of the remote machine <b>30</b>, such as an exclusive OR (XOR) gate.

0936In one embodiment, the encryptor <b>5010</b> stores the encrypted authentication credentials with the SID in a table <b>5020</b> in memory <b>5018</b>. In another embodiment, the encryptor <b>5010</b> stores the encrypted authentication credentials in the table <b>5020</b> and the SID generator <b>5008</b> stores the SID in the table <b>5020</b>. In one embodiment, the table <b>5020</b> is an area in memory <b>5018</b> allocated by the processor <b>5016</b> for us by the encryptor <b>5010</b>. In another embodiment, the encryptor <b>5010</b> stores the encrypted authentication credentials with the SID in a database (not shown in <figref idref="DRAWINGS">FIG. 50</figref>) separate from memory <b>5018</b>.

0937In one embodiment, the ACR Service <b>5002</b> uses the SID as a vector to the location of the encrypted authentication credentials in the table <b>5020</b>. In another embodiment, the ACR Service <b>5002</b> uses the SID as a database key to locate and retrieve the encrypted authentication credentials in a database (not shown in <figref idref="DRAWINGS">FIG. 50</figref>). Each encrypted authentication credential created by the encryptor <b>5010</b> is associated with only one unique SID. Thus, the ACR Service <b>5002</b> can locate and retrieve the encrypted authentication credentials by using a particular SID.

0938The key destroyer <b>5012</b> deletes the key once the ACR Service <b>5002</b> determines that the key is no longer needed. In one embodiment, the key destroyer <b>5012</b> is a delete function of a software program such as the operating system of the remote machine <b>30</b>.

0939The decryptor <b>5014</b> decrypts the encrypted authentication credentials once the ACR Service <b>5002</b> receives the key and the SID from the client machine <b>10</b>. In one embodiment, the decryptor <b>5014</b> is a software module that performs the inverse function or algorithm that the encryptor <b>5010</b> performed to create the encrypted credentials. In another embodiment, the decryptor <b>5014</b> is a hardware component (e.g. a logic gate) to perform the inverse operation of the encryptor <b>5010</b>.

0940In one embodiment, one or more of the key generator <b>5006</b>, the SID generator <b>5008</b>, the encryptor <b>5010</b>, the key destroyer <b>5012</b> and the decryptor <b>5014</b> are joined into one software module representing the ACR Service <b>5002</b>. In another embodiment, these components can be hardware components such as logic gates. In a further embodiment, these components are included in a single integrated circuit. In yet another embodiment, some of the components, for example the key generator <b>5006</b> and the SID generator <b>5008</b>, can be hardware components, and other components, for example the encryptor <b>5010</b>, the key destroyer <b>5012</b> and the decryptor <b>5014</b>, can be software components.

0941In another embodiment, methods for reconnecting a client machine <b>10</b> to a remote machine <b>30</b> when there is a disruption in the client's connection to the network are provided. The methods include re-establishing the client's connection to the remote machine <b>30</b> and using the ACR Service <b>5002</b> to re-authenticate the client to the host service.

0942Referring to <figref idref="DRAWINGS">FIG. 51</figref>, the client machine <b>10</b> establishes a first communication session with the remote machine <b>30</b> over the communication channel <b>5004</b>. The client machine <b>10</b> obtains (step <b>54100</b>) authentication credentials from a user of the client machine <b>10</b>. In a system <b>4500</b> not using an Open System Interconnection (OSI) protocol as the transmission protocol for communications between the client machine <b>10</b> and the remote machine <b>30</b>, the authentication credentials may be a login password that is needed to establish the first communication session. In this embodiment, the obtaining of the authentication credentials from the user precedes the establishment of the communication session. In another embodiment, the authentication credential is personal information of the user that the client machine <b>10</b> obtains after the first communication session has been established. Examples of authentication credentials include a login password, a social security number, a telephone number, an address, biometric information, a time-varying pass code and a digital certification. The client machine <b>10</b> then transmits (step <b>5405</b>) the authentication credentials to the remote machine <b>30</b> over the communication channel <b>5004</b> so that the remote machine <b>30</b> can authenticate the client machine <b>10</b> or the user of the client machine <b>10</b>.

0943After the remote machine <b>30</b> receives the authentication credentials, the ACR Service <b>5002</b> provides its auto client reconnect services. The key generator <b>5006</b> creates (step <b>5410</b>) a first encryption key for use with the authentication credentials. In one embodiment, the encryption key is a random number. In another embodiment, the encryption key is any standard cryptographic key. The encryptor <b>5010</b> then encrypts (step <b>5415</b>) the authentication credentials with the first key to generate encrypted authentication credentials. This prevents an attacker who gains access to the remote machine <b>30</b> from accessing the authentication credentials without the key. The SID generator <b>5008</b> then creates (step <b>5120</b>) a first SID to identify the first communication session between a client machine <b>10</b> and the remote machine <b>30</b>. In one embodiment, the first communication session is with a host service <b>4516</b> hosted by the remote machine <b>30</b>. The encryptor <b>5010</b> then stores (step <b>5425</b>) the encrypted authentication credentials with the first SID in the table <b>5020</b> described above.

0944In one embodiment, the encryptor <b>5010</b> stores the encrypted authentication credentials with the first SID in a certain location for more efficient retrieval at a later time. For instance, the encryptor <b>5010</b> stores all encrypted authentication credentials and SIDs that have been created within a predetermined amount of time in RAM. The ACR service <b>5002</b> transfers all encrypted authentication credentials and SIDS created before a predetermined time to a second, external memory (not shown). In another embodiment, the encryptor <b>5010</b> stores the encrypted authentication credentials with the SID in a database (not shown).

0945The SID and the encrypted authentication credentials stored in the memory <b>5018</b> can be arranged in any particular order and/or format. For example, the SID and encrypted authentication credentials can be stored in chronological order with respect to the creation time of the encrypted authentication credentials.

0946The remote machine <b>30</b> then transmits (step <b>5430</b>) the first key and associated first SID to the client machine <b>10</b> over the network <b>150</b>. The client machine <b>10</b> stores (step <b>5435</b>) the first key and the first SID in memory (not shown). Then the key destroyer <b>5012</b> of the ACR Service <b>5002</b> deletes (step <b>5440</b>) the key stored in memory <b>5018</b>.

0947In another embodiment, the ACR Service <b>5002</b> does not delete the first key from memory <b>5018</b> until the ACR Service <b>5002</b> has notification that the client machine <b>10</b> has received the key. For example, the client machine <b>10</b> transmits an acknowledgment message to the remote machine <b>30</b> after the client machine <b>10</b> successfully received the key. Once the ACR Service <b>5002</b> receives notification, the key destroyer <b>5012</b> then deletes (step <b>5440</b>) the key from the memory <b>5018</b>. This prevents the ACR Service <b>5002</b> from deleting the key before the client machine <b>10</b> successfully received the key. By not deleting the key until the acknowledgment message, the ACR Service <b>5002</b> can retransmit the key and the SID to the client machine <b>10</b> upon a failure in the transmission.

0948By deleting the key in step <b>5440</b>, the ACR Service <b>5002</b> does not have the mechanism needed to decrypt the encrypted authentication credentials stored in the table <b>5020</b>. Thus, if an attacker accesses the memory <b>5018</b> of the remote machine <b>30</b>, the attacker can retrieve the encrypted authentication credentials but cannot decrypt the encrypted authentication credentials. Therefore, the attacker cannot read the authentication credentials. In short, the encrypted authentication credentials stored on the remote machine <b>30</b> do not provide any information that the attacker can interpret or understand. As such, the remote machine <b>30</b> does not possess any information to decrypt the encrypted authentication credentials.

0949In addition, the client machine <b>10</b> is the only device that can provide the key to the encrypted authentication credentials. With the possibility of many client machines <b>10</b> as part of the network <b>150</b>, an attacker may have to attempt to gain access to each client (e.g. <b>10</b>, <b>10</b>′) individually to find the client machine <b>10</b> that possesses the correct key. This can be time consuming and tedious and, as a result, may deter an attacker from an attempt to decrypt the encrypted authentication credentials.

0950In another embodiment, the remote machine <b>30</b> has a timeout feature with respect to accessing the encrypted authentication credentials. For instance, the remote machine <b>30</b> starts a timer after the first communication is abnormally terminated. If the timer reached a predetermined value before the client machine <b>10</b> re-establishes the second communication session and transmits the key to the remote machine <b>30</b> for decryption, the ACR Service <b>5002</b> deletes the encrypted authentication credentials from the table <b>5020</b>. If no timer is used, the key acts as a de facto password for future sessions.

0951Once the client machine <b>10</b> receives the first key and the first SID from the remote machine <b>30</b> as described above in reference to <figref idref="DRAWINGS">FIG. 51</figref>, the session can be re-established, as shown in <figref idref="DRAWINGS">FIG. 52</figref>, without requiring the user to reenter his or her authentication credentials. When a disruption or break occurs in the first communication session (step <b>54100</b>) between the client machine <b>10</b> and the remote machine <b>30</b>, the first communication session <b>5004</b> needs to be reestablished and the client machine <b>10</b> re-authenticated to the remote machine <b>30</b>. The ACR Service <b>5002</b> provides a system and method for re-establishing and re-authenticating the client machine <b>10</b> to the remote machine <b>30</b>.

0952When the client machine <b>10</b> and the remote machine <b>30</b> re-establish a second communication session, the client machine <b>10</b> transmits the first key and the first SID (step <b>5405</b>) to the remote machine <b>30</b>. The ACR Service <b>5002</b> uses the SID (step <b>5210</b>) to locate and retrieve the encrypted authentication credentials in the server's memory <b>5018</b> and uses the key (step <b>5215</b>) to decrypt the retrieved authentication credentials. The remote machine <b>30</b> then re-authenticates the client machine <b>10</b> to the remote machine <b>30</b> (step <b>5220</b>) by validating the authentication credentials from the client machine <b>10</b>. In one embodiment, the authentication and re-authentication is facilitated through the security services provided by the operating system of the computing device of the remote machine <b>30</b>. For example, the authentication credentials are a login and password to the remote machine <b>30</b>. In another embodiment, the authentication and re-authentication is facilitated through application level security services of an application or software program on the remote machine <b>30</b>. For example, the authentication credentials are an application login and password to a specific host service <b>4516</b>.

0953To illustrate, upon an abnormal termination of a first communication session (step <b>54100</b>) in which the user's login password was the authentication credential, the client machine <b>10</b> attempts to establish a second communication session with the remote machine <b>30</b>. As part of the request to the remote machine <b>30</b> to establish a second communication session with the remote machine <b>30</b>, the client machine <b>10</b> transmits the key and the SID (step <b>5405</b>) of the first terminated communication session to the remote machine <b>30</b>. Instead of prompting the user to enter the user's login password again, the remote machine <b>30</b>, through the ACR Service <b>5002</b>, uses the SID (step <b>5210</b>) to locate and retrieve the encrypted authentication credentials associated with the user, uses the key (step <b>5215</b>) to decrypt the retrieved authentication credentials, and reauthenticates the client using the decrypted authentication information (step <b>5220</b>).

0954In one embodiment, during the second communication session, the ACR Service <b>5002</b> creates (step <b>5225</b>) a second key for the authentication credentials and then encrypts (step <b>5230</b>) the authentication credentials using the second key. A second SID is created (step <b>5235</b>) to identify the second communication session and associate the session with the client machine <b>10</b>. The second encrypted authentication credentials are stored (step <b>5425</b>) with the second SID in the table <b>5020</b>.

0955In this embodiment, the server then transmits (step <b>5240</b>) the second key and the second SID to the client machine <b>10</b>. The client machine <b>10</b> then stores (step <b>5245</b>) the second key and the second SID in memory (not shown) for future retrieval. The ACR Service <b>5002</b> then deletes (Step <b>54150</b>) the second key from the memory <b>5018</b>. Thus, the ACR Service <b>5002</b> can only decrypt the second encrypted authentication upon obtaining the second key and the second SID from the client machine <b>10</b>. The ACR Service <b>5002</b> has created a new key and a new SID for the second communication session that is used with the same authentication credentials that the user had transmitted during the first communication session. Therefore, a user's authentication credentials do not have to be retransmitted upon a second communication channel after an abnormal termination of the first communication session.

0956Although the invention is discussed in terms of authentication credentials, any confidential information which can be maintained across sessions if there is a communication failure can be used. Thus if credit card information is required by an application and the credit card information is sent to the server, the subsequent disconnect between the client and the server does not require the credit card information to be reentered if this invention is issued. Further, although a session identifier, or SID, is discussed as providing a pointer to the stored authentication credentials, any number or value which is suitable as a pointer may be used.

0957<figref idref="DRAWINGS">FIG. 53</figref> depicts another embodiment of a system <b>5300</b> that is capable of reconnecting a client machine <b>10</b> to a remote machine <b>30</b> using an ACR Service <b>5002</b> executing on an intermediary machine <b>30</b>′. The intermediary machine <b>30</b>′ is a computing device different from the remote machine <b>30</b> and can be any remote machine <b>30</b> that is capable of communication and that has sufficient processor power and memory capacity to perform the operations described herein. In brief overview, the client machine <b>10</b> is in communication with an intermediary machine <b>30</b>′ over a communication channel <b>5004</b>. The communication channel <b>5004</b> may include a network <b>150</b>. The intermediary machine <b>30</b>′ provides auto client reconnect services, via an ACR Service <b>5002</b>, to the client machine <b>10</b> for the connection of the client machine <b>10</b> to the remote machine <b>30</b>. The intermediary machine <b>30</b>′ is in communications with the remote machine <b>30</b> over a communication channel <b>5004</b>′. The communication channel <b>5004</b>′ may include a network <b>150</b>′. The client machine <b>10</b> accesses the services of the remote machine <b>30</b> through the intermediary machine <b>30</b>′. The ACR Service <b>5002</b> on the intermediary machine <b>30</b>′ provides auto client reconnect services for the connection of the client machine <b>10</b> to the remote machine <b>30</b>. Although illustrated with a single client machine <b>10</b> over a communication channel <b>5004</b>, any number of clients and number of communication channels can be part of the system <b>5300</b>.

0958In a further embodiment (not shown), the system <b>5300</b> includes multiple intermediary machines <b>30</b>′ that are in communication with one or more client machines <b>10</b> through a network <b>150</b> over additional communication channels <b>5004</b>, <b>5004</b>′. Although illustrated in <figref idref="DRAWINGS">FIG. 53</figref> with a single intermediary machine <b>30</b>′ over a communication channel <b>5004</b>, any number of intermediary nodes and number of communication channels can part of the system <b>5300</b>.

0959In another embodiment, the invention relates to methods to facilitate establishing and authenticating a client machine's <b>10</b> connection to a remote machine <b>30</b> using one or more intermediary machines <b>30</b>′. As shown in <figref idref="DRAWINGS">FIG. 54</figref>, an intermediary machine <b>30</b>′ establishes a session with the remote machine <b>30</b>.

0960The client machine <b>10</b> establishes a first communication session with the intermediary machine <b>30</b>′ over the communication channel <b>5004</b>. The client machine <b>10</b> obtains (step <b>5400</b>) authentication credentials from a user of the client machine <b>10</b>. The client machine <b>10</b> then transmits (step <b>5405</b>) the authentication credentials to the intermediary machine <b>30</b>′ over the communication channel <b>5004</b> so that the intermediary machine <b>30</b>′ can authenticate the user with the remote machine <b>30</b>.

0961After the intermediary machine <b>30</b>′ receives the authentication credentials, the ACR Service <b>5002</b> provides its auto client reconnect services. The ACR Service <b>5002</b> creates (step <b>5410</b>) a first encryption key for use with the authentication credentials and then encrypts (step <b>5415</b>) the authentication credentials with the first key to generate encrypted authentication credentials. This prevents an attacker who gains access to the remote machine <b>30</b> from accessing the authentication credentials without the key. Then a session is established with the remote machine <b>30</b> (step <b>5420</b>A) and the client machine <b>10</b> is authenticated to the remote machine <b>30</b> using the authentication credentials. Thereby, the ACR Service <b>5002</b> creates a first SID to identify the first communication session. The encrypted authentication credentials are stored (step <b>5425</b>) with the first SID in the table <b>5020</b> described above. The intermediary machine <b>30</b>′ then transmits (step <b>5430</b>) the first key and the first SID to the client machine <b>10</b> over the network <b>150</b>. The client machine <b>10</b> stores (step <b>5435</b>) the first key and the first SID in the client machine's memory (not shown). The ACR Service <b>5002</b> then deletes (step <b>5440</b>) the key stored in memory <b>5018</b>.

0962Once the client machine <b>10</b> receives the first key and the first SID from the intermediary machine <b>30</b>′ as described above in reference to <figref idref="DRAWINGS">FIG. 54</figref>, the communication session can be re-established and re-authenticated, as shown in <figref idref="DRAWINGS">FIG. 55</figref>, without requiring the user to reenter his or her authentication credentials. For example, there may be a disruption in the first communication session (step <b>5505</b>) between the client machine <b>10</b> and the intermediary machine <b>30</b>′ from an abnormal termination.

0963When the client machine <b>10</b> and the intermediary machine <b>30</b>′ re-establish a second communication session, the client machine <b>10</b> transmits the first key and the first SID (step <b>5505</b>) to the intermediary machine <b>30</b>′. The ACR Service <b>5002</b> of the intermediary machine <b>30</b>′ uses the SID (step <b>5510</b>) to locate and retrieve the encrypted authentication credentials in the server's memory <b>5018</b> and uses the key (step <b>5515</b>) to decrypt the retrieved authentication credentials. The key generator creates (step <b>5520</b>) a second key for the authentication credentials and the key encryptor <b>5010</b> then encrypts (step <b>5525</b>) the authentication credentials using the second key. The SID generator <b>5008</b> also creates (step <b>5530</b>) a second SID to identify the second communication session and associates it with the maintained session between the intermediary machine <b>30</b>′ and the remote machine <b>30</b>. The encryptor <b>5010</b> stores the second encrypted authentication credentials with the second SID in the table <b>5020</b>.

0964In this embodiment, the remote machine <b>30</b> then transmits (step <b>5535</b>) the second key and the second SID to the client machine <b>10</b>. The client machine <b>10</b> then stores (step <b>5540</b>) the second key and the second SID for future retrieval. The key destroyer <b>5012</b> then deletes (Step <b>5545</b>) the second key from the memory <b>5018</b>. Thus, the ACR Service <b>5002</b> can only decrypt the second encrypted authentication upon obtaining the second key and the second SID from the client machine <b>10</b>. The ACR Service <b>5002</b> has created a new key and a new SID for the second communication session that is used with the same authentication credentials that the user had transmitted during the first communication session. Therefore, a user's authentication credentials do not have to be retransmitted upon a second communication channel after an abnormal termination of the first communication session.

0965In another embodiment, there may be a disruption or abnormal termination in the second communication session (step <b>5600</b>) between the intermediary machine <b>30</b>′ and the remote machine <b>30</b>. As described in <figref idref="DRAWINGS">FIG. 56</figref>, the second communication session can be re-established and re-authenticated without requiring the user to reenter his or her authentication credentials.

0966When the intermediary machine <b>30</b>′ and the remote machine <b>30</b> re-establish a second communication session, the intermediary machine <b>30</b>′ requests (step <b>5605</b>) the first key and first SID from the client machine <b>10</b> to re-establish a session with the remote machine <b>30</b> on the client's behalf. In response, the client machine <b>10</b> transmits the first key and the first SID (step <b>5610</b>) to the intermediary machine <b>30</b>′. The ACR Service <b>5002</b> of the intermediary machine <b>30</b>′ uses the SID (step <b>5615</b>) to locate and retrieve the encrypted authentication credentials in the server's memory <b>5018</b> and uses the key (step <b>5620</b>) to decrypt the retrieved authentication credentials. The ACR Service <b>500</b> then re-establishes the client's session with the server (step <b>5625</b>) using the decrypted authentication credentials to re-authenticate the client machine <b>10</b> to the remote machine <b>30</b>.

0967In another embodiment, after re-establishing and re-authenticating the client over the second communication session, the ACR Service <b>5002</b> of the intermediary machine <b>30</b>′ creates a replacement second SID and second key as previously described in <figref idref="DRAWINGS">FIG. 55</figref>. In reference to the embodiment of the ACR Service illustrated in <figref idref="DRAWINGS">FIG. 50</figref>, the key generator creates (step <b>5520</b>) a second key for the authentication credentials and the key encryptor <b>5010</b> then encrypts (step <b>5525</b>) the authentication credentials using the second key. The SID generator <b>5008</b> also creates (step <b>5530</b>) a second SID to identify the second communication session and associates it with the re-established session between the intermediary machine <b>30</b>′ and the remote machine <b>30</b>. The encryptor <b>5010</b> stores the second encrypted authentication credentials with the second SID in the table <b>5020</b>. In this embodiment, the server then transmits (step <b>5535</b>) the second key and the second SID to the client machine <b>10</b>. The client machine <b>10</b> then stores (step <b>5540</b>) the second key and the second SID for future retrieval. The key destroyer <b>5012</b> then deletes (Step <b>5545</b>) the second key from the memory <b>5018</b>.

0968In other embodiments, one or more of the first protocol service <b>4502</b> and ACR Service <b>5002</b> can be distributed across any of the host service nodes. As such, the functionality of re-establishing and re-authenticating, or automatically reconnecting, a client machine <b>10</b> connect to a host service <b>4516</b> can be flexibly distributed in different system and deployment architectures across host services <b>4516</b> and/or remote machines <b>30</b>.

0969In one embodiment, an ACR Service <b>5002</b> can be associated with each of the host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>in system <b>4500</b> to provide auto client reconnect services dedicated to each host service <b>4516</b>, respectively. A single first protocol service <b>4502</b> can be deployed to handle all of the host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. As shown in <figref idref="DRAWINGS">FIG. 57</figref>, each of the multiple ACR Services <b>5002</b><i>a</i>-<b>5002</b><i>n </i>is associated with each of the host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>, respectively. By way of example, a client machine <b>10</b> establishes a communication session with the host service <b>4516</b><i>a </i>using the first protocol service <b>4502</b>. The ACR Service <b>5002</b><i>a </i>associated with host service <b>4516</b><i>a </i>provides auto client reconnect services for the connection of the client machine <b>10</b> to the host service <b>4516</b><i>a</i>. If there is a disruption in a network connection, the first protocol service <b>4502</b> will re-establish the connection with the client machine <b>10</b> and the ACR Service <b>5002</b><i>a </i>will re-authenticate the client machine <b>10</b> to the host service <b>4516</b><i>a</i>. A second client machine <b>10</b>′ may concurrently, with the first client machine <b>10</b>, establish a communication session with the host service <b>4516</b><i>b </i>using the first protocol service <b>4502</b>. The ACR Service <b>5002</b><i>b </i>provides auto client reconnect services for the client's connection to the host service <b>4516</b><i>b</i>. If there is a network disruption, the first protocol service <b>4502</b> in conjunction with the ACR Service <b>5002</b><i>b </i>will reconnect the client machine <b>10</b>′ to the host service <b>4516</b><i>b. </i>

0970In another embodiment of these methods, an ACR service can be associated with each of the multiple host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>running on each of the remote machines <b>30</b> of the system <b>4500</b>. A first protocol service <b>4502</b> can be deployed on each remote machine <b>30</b> to service each of the multiple remote machines <b>30</b> running on that host node <b>118</b>. As shown in <figref idref="DRAWINGS">FIG. 57</figref>, each ACR service <b>5002</b><i>a</i>-<b>5002</b><i>n </i>is associated with each host service <b>4516</b><i>a</i>-<b>4516</b><i>n</i>, respectively. Each remote machine <b>30</b> has a dedicated first protocol service <b>4502</b> servicing each of its host services <b>4516</b> and each ACR Service <b>5002</b>. For example, a client machine <b>10</b> establishes a communication session with host service <b>4516</b><i>a </i>on remote machine <b>30</b> by using the first protocol service <b>4502</b>. The ACR Service <b>5002</b><i>a </i>on remote machine <b>30</b> provides auto client reconnect services for the connection of the client machine <b>10</b> to the host service <b>4516</b><i>a </i>on remote machine <b>30</b>.

0971If a network disruption is detected, the first protocol service <b>4502</b> reestablishes the client's connection to the host service <b>4516</b><i>a </i>on remote machine <b>30</b> and the ACR service <b>5002</b><i>a </i>on remote machine <b>30</b> re-authenticates the client machine <b>10</b> to the host service <b>4516</b><i>a </i>on remote machine <b>30</b>. Concurrently with the first client machine <b>10</b>, a second client machine <b>10</b>′ establishes a communication session with host service <b>4516</b><i>b </i>on remote machine <b>30</b> using the first protocol service <b>4502</b> and ACR Service <b>5002</b><i>a</i>. If there is a network disruption, the first protocol service <b>4502</b> in conjunction with the ACR Service <b>5002</b><i>a </i>reconnect the client machine <b>10</b>′ with host service <b>4516</b><i>b </i>on remote machine <b>30</b>. Concurrently with the first client machine <b>10</b> and the second client machine <b>10</b>′, a third client machine <b>10</b>“establishes a communication session with host service <b>4516</b><i>n </i>on remote machine <b>30</b>′ using the first protocol service <b>4502</b> and ACR Service <b>5002</b><i>n </i>on remote machine <b>30</b>′. In a similar manner, the first protocol service <b>4502</b> and ACR Service <b>5002</b><i>n </i>can reconnect the client machine <b>10</b>″ to the host service <b>4516</b><i>n </i>of remote machine <b>30</b>′.

0972In other embodiments, one or more of the ACR Services <b>5002</b> can be distributed with the first protocol services <b>4502</b> across any of the intermediary or first protocol services nodes. As such, the functionality of reconnecting a client machine <b>10</b> to a host service <b>4516</b> can be flexibly distributed in different system and deployment architectures associated with the first protocol service <b>4502</b>.

0973In one embodiment of this aspect of the invention, the ACR Service <b>5002</b> can be associated with each first protocol service <b>4502</b> to provide auto client reconnect services dedicated to the first protocol service <b>4502</b>. A single first protocol service <b>4502</b> and ACR Service <b>5002</b> can be deployed to handle all of the host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. As shown in <figref idref="DRAWINGS">FIG. 59</figref>, the ACR Service <b>5002</b> resides with the first protocol service <b>4502</b> on the same computing device to provide auto client reconnect services to host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. For example, a client machine <b>10</b> establishes a communication session with any of the host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>by using the first protocol service <b>4502</b> and ACR Service <b>5002</b>. The first protocol service <b>4502</b> and ACR Service <b>5002</b> provide reconnecting functionality from a client machine <b>10</b> to any of the host services <b>4516</b><i>a</i>-<b>4516</b><i>n. </i>

0974In another embodiment of this aspect of the invention, each of the ACR Services <b>5002</b><i>a</i>-<b>5002</b><i>n </i>can be associated with each of the multiple of first protocol services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. For example as shown in <figref idref="DRAWINGS">FIG. 60</figref>, a first protocol service <b>4502</b> and an ACR Service <b>5002</b><i>a </i>can be deployed on a remote machine <b>30</b> to service each of the multiple host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>running on that remote machine <b>30</b>. As further shown in <figref idref="DRAWINGS">FIG. 60</figref>, each ACR service <b>5002</b><i>a</i>-<b>405</b><i>n </i>is associated with each first protocol service <b>4502</b>-<b>112</b><i>n </i>to provide dedicated auto client reconnect services to the multiple host services <b>4516</b><i>a</i>-<b>4516</b><i>n </i>of each remote machine <b>30</b>-<b>118</b><i>n</i>. By way of example, client machine <b>10</b> establishes a communication session with host service <b>4516</b><i>a </i>on remote machine <b>30</b> by using the first protocol service <b>4502</b> and ACR Service <b>5002</b><i>a </i>on the same remote machine <b>30</b>. If there is a network disruption, the first protocol service <b>4502</b> in conjunction with the ACR Service <b>5002</b><i>a </i>reconnects the client machine <b>10</b> to the host service <b>4516</b><i>a </i>on the remote machine <b>30</b>.

0975Although the invention is discussed above in terms of various system and deployment architectures in <figref idref="DRAWINGS">FIGS. 57-60</figref>, any other system and/or deployment architecture that combines and/or distributes one or more of the first protocol service(s) <b>4502</b>, ACR Service(s) <b>5002</b>, and host service(s) <b>4516</b> across any of the remote machines <b>30</b>, intermediary machines <b>30</b>′ or other computing devices can be used.

0976Furthermore, instead of using an ACR Service <b>5002</b> to provide authentication and re-authentication services, a ticket authority <b>6102</b> service can be used. A ticket authority <b>6102</b> generates and validates tickets for connection and authentication purposes. A ticket can comprise a session identifier and key. It can also comprise a random number, an application server certificate, a nonce, a constant or null value or any other type of identification, confidential or security based information that may be used for such purposes.

0977In an embodiment of a network communication system for reconnecting a client machine <b>10</b> to a host service <b>4516</b> as shown in <figref idref="DRAWINGS">FIG. 61</figref>, a ticket authority <b>6102</b> can run on a node separate from the intermediary machine <b>30</b>, first protocol service <b>4502</b> or any of the host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. <figref idref="DRAWINGS">FIG. 61</figref> depicts an intermediary machine <b>30</b> and ticket authority <b>6102</b>, which could be a single computing device, as part of the system <b>4500</b>. In addition to the networks <b>150</b> and <b>150</b>′, the system <b>4500</b> includes a client machine <b>10</b>, first protocol service <b>4502</b>, and the host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>, all of which are described above. In one embodiment, the intermediary machine <b>30</b> is a security gateway, such as, for example, a firewall and/or a router, through which messages between the client machine <b>10</b> and the first protocol service <b>4502</b> must pass due to the configuration of the network <b>150</b>. The ticket authority <b>6102</b> can be, for example, a stand-alone network component that is capable of communication and that has sufficient processor power and memory capacity to perform the operations described herein. The ticket authority <b>6102</b> also can be a specific host service <b>4516</b> dedicated to providing ticket related services on a remote machine <b>30</b>.

0978As shown in an embodiment of <figref idref="DRAWINGS">FIG. 61</figref>, the intermediary machine <b>30</b> is configured to accept a connection <b>4504</b><i>a </i>initiated by the client machine <b>10</b> and to establish a second connection <b>4504</b><i>b </i>with the first protocol service <b>4502</b>. Together, the connection <b>4504</b><i>a </i>and the second connection <b>4504</b><i>b </i>constitute the connection <b>4504</b>, described above, over which the client machine <b>10</b> and the first protocol service <b>4502</b> communicate using the first protocol.

0979The intermediary machine <b>30</b>, as shown, is also configured to communicate with the ticket authority <b>6102</b>. In one embodiment, the ticket authority <b>6102</b> is configured to receive a request for a first reconnection ticket from the intermediate node <b>30</b>′ and to thereafter generate the first reconnection ticket. The first reconnection ticket can include, for example, a large random number. The first reconnection ticket allows the client machine <b>10</b> to automatically re-establish a connection with the host service after an abnormal disruption of service without requiring the client machine <b>10</b> to provide authentication credentials again.

0980In another embodiment, the ticket authority <b>6102</b> is configured to receive a request for a first re-connection ticket for each of the “hops” between the client machine <b>10</b> and host service <b>4516</b>. For example, the intermediary machine <b>30</b> may request re-connection tickets for the connection between the client machine <b>10</b> and the intermediary machine <b>30</b>, between the intermediary machine <b>30</b> and the first protocol service <b>4502</b>, and between the first protocol service <b>4502</b> and the host service <b>4516</b>. These re-connection tickets may only be valid for each of the “hops”. For example, a first re-connection ticket for the first protocol service <b>4502</b> to host service <b>4516</b> connection is valid only for authenticating the first protocol service <b>4502</b> to the host service <b>4516</b> on behalf of the client machine <b>10</b>.

0981After generation of the first reconnection ticket, the ticket authority <b>6102</b> encrypts the authentication credentials supplied by the client machine <b>10</b> using the first reconnection ticket so that an attacker who gains access to the intermediary machine <b>30</b> or the ticket authority <b>6102</b> cannot access the authentication credentials without the first reconnection ticket. The ticket authority <b>6102</b> may also generate a SID to identify the communication session that is established between the client machine <b>10</b> and the intermediary machine <b>30</b>. The ticket authority <b>6102</b> then stores the encrypted authentication credentials with the SID in memory and transmits the SID and the first reconnection ticket to the client machine <b>10</b> over the network <b>150</b>. Upon the client's receipt of the SID and the first reconnection ticket, the ticket authority <b>6102</b> destroys (i.e., deletes) the ticket from its memory (not shown).

0982In another embodiment, the ticket authority <b>6102</b> is configured to generate a handle. The handle can be, for example, a random number that is associated with (e.g., mapped to) the first reconnection ticket. In one embodiment, the handle is a smaller random number than the random number forming the first reconnection ticket. For example, the handle may be a 32-bit random number. In a further embodiment, the handle associated with a ticket or a re-connection ticket is an address of or pointer to the next “hop” in the multiple-hop connection between the client machine <b>10</b> and the host service <b>4516</b>. In this case, a ticket or re-connection ticket is validated for a single “hop” with a pointer to the next “hop”. The next “hop” will need to obtain and validate a different ticket or re-connection ticket and so forth until the last “hop” is validated and connected to the host service <b>4516</b> on behalf of the client machine <b>10</b>.

0983The ticket authority <b>6102</b> transmits the first reconnection ticket and the handle to the intermediary machine <b>30</b>, while keeping a copy of the first reconnection ticket and a copy of the handle. The copy of the first reconnection ticket can later be used by the ticket authority <b>6102</b> to validate the first reconnection ticket originally transmitted to the client machine <b>10</b> when it is later presented to the ticket authority <b>6102</b> during the process of reconnecting the client machine <b>10</b>. In one embodiment, the ticket authority <b>6102</b> also keeps an address for the first protocol service <b>4502</b>, which, as explained below, is associated with the first reconnection ticket and, upon validation of the first reconnection ticket, is transmitted to the intermediary machine <b>30</b>.

0984In one embodiment, the intermediary machine <b>30</b> is further configured to use the handle transmitted to it by the ticket authority <b>6102</b> to delete the copy of the first reconnection ticket kept at the ticket authority <b>6102</b>. In another embodiment, as described below, the ticket authority <b>6102</b> is further configured to delete, during the process of reconnecting the client machine <b>10</b> to a host service <b>4516</b>, the first reconnection ticket and thereafter generate a replacement first reconnection ticket. Additionally, in another embodiment, the first reconnection ticket is configured for automatic deletion after a pre-determined period of time. In the embodiment of re-connection tickets for each of the “hops” between the client and the host service <b>4516</b>, one, some or all of the re-connection tickets may be configured for automatic deletion after a pre-determined period of time. In other embodiments, the ticket authority <b>6102</b> or the intermediary machine <b>30</b> is configured to delete each of the multiple-hop tickets and generate replacement tickets

0985In another embodiment, the first protocol service <b>4502</b> is configured to generate a second reconnection ticket, which, as in the case of the first reconnection ticket, can include, for example, a large random number. In one embodiment, the first protocol service <b>4502</b> generates second re-connection tickets for each of the “hops” between the client machine <b>10</b> and the host service <b>4516</b>. The first protocol service <b>4502</b> can also be configured to transmit the second reconnection ticket to the client machine <b>10</b>, while keeping a copy of the second reconnection ticket and a session number. The copy of the second reconnection ticket can later be used by the first protocol service <b>4502</b> to validate the second reconnection ticket originally transmitted to the client machine <b>10</b> when it is later presented to the first protocol service <b>4502</b> during the process of reconnecting the client machine <b>10</b>. In one embodiment, the first protocol service <b>4502</b> transmits the second reconnection ticket to the client machine <b>10</b> via the intermediary machine <b>30</b>. In another embodiment, the first protocol service <b>4502</b> transmits the second reconnection ticket to the client machine <b>10</b> directly. In a further embodiment, the first protocol service <b>4502</b> may transmit second re-connection tickets to other first protocol services <b>4502</b> or intermediary machines <b>30</b> that may comprise the multiple-hop connection between the client machine <b>10</b> and the host service <b>4516</b>.

0986Moreover, as described in greater detail below, the first protocol service <b>4502</b> can be further configured to delete, during the process of reconnecting the client machine <b>10</b> to a host service <b>4516</b>, the second reconnection ticket, and thereafter generate a replacement second reconnection ticket. Additionally, in another embodiment, the second reconnection ticket is configured for automatic deletion after a pre-determined period of time. In further embodiments, a first protocol service <b>4502</b> of one or more first protocol services <b>4502</b> in a multiple-hop connection is configured to delete the second re-connection tickets for each of the “hops”, and thereafter generate replacement second re-connection tickets for one, some or all of the “hops.”

0987In one embodiment, the intermediary machine <b>30</b> serves as an intermediary for the first and second reconnection tickets. The intermediary machine <b>30</b> receives, for example, the first reconnection ticket generated by the ticket authority <b>6102</b> and the second reconnection ticket generated by the first protocol service <b>4502</b>. The intermediary machine <b>30</b> can then transmit the first reconnection ticket and the second reconnection ticket to the client machine <b>10</b>. Moreover, during the process of reconnecting the client machine <b>10</b> to a host service <b>4516</b>, the intermediary machine <b>30</b> can accept the first reconnection ticket and the second reconnection ticket from the client machine <b>10</b> and thereafter transmit the first reconnection ticket to the ticket authority <b>6102</b> and, if appropriate, the second reconnection ticket to the first protocol service <b>4502</b>.

0988In another embodiment, the intermediary node <b>632</b> serves as an intermediary for the re-connection tickets for the multiple-hops between the client machine <b>10</b> and the host service <b>4516</b>. The intermediary machine <b>30</b> receives, for example, the first re-connection ticket for the client machine <b>10</b> to first protocol service <b>4502</b> connection and the first re-connection ticket for the first protocol service <b>4502</b> to the host service <b>4516</b>. In a further embodiment, the intermediary machine <b>30</b> receives a first re-connection ticket for the connection between the intermediary machine <b>30</b> and the first protocol service <b>4502</b>. The intermediary machine <b>30</b> can then transmit the first re-connection ticket for the client to the client machine <b>10</b> and the first re-connection ticket for the first protocol service <b>4502</b> to the first protocol service <b>4502</b>. Moreover, during the process of re-connecting the client machine <b>10</b> to a host service <b>4516</b>, the intermediary machine <b>30</b> can accept the first re-connection ticket from the client machine <b>10</b> to validate the ticket to re-establish the client's connection to the intermediary machine <b>30</b> or the first protocol service <b>4502</b>.

0989If the first communication session between the client machine <b>10</b> and the host service <b>4516</b> terminates, for example abnormally, the new session can be re-established without requiring the user to reenter his or her authentication credentials. When the client machine <b>10</b> and the host service <b>4516</b> re-establish a second communication session, the client machine <b>10</b> retransmits the first and second reconnection tickets and the SID to the intermediary machine <b>30</b>. The intermediary machine <b>30</b> transmits the first and second reconnection tickets and the SID to the ticket authority <b>6102</b>, which uses the SID to locate and retrieve the encrypted authentication credentials for the first connection and uses the first reconnection ticket to decrypt the retrieved authentication credentials. The ticket authority <b>6102</b> then authenticates the client by validating the decrypted authentication credentials. After re-authentication, the second reconnection ticket is forwarded to the first protocol service <b>4502</b> to re-establish the second connection <b>4508</b> with the host service <b>4516</b>.

0990In another embodiment of a network communications system <b>6100</b> as shown in <figref idref="DRAWINGS">FIGS. 62 and 63</figref>, the client machine <b>10</b> uses the web browser <b>6302</b> to request access to a resource and a first remote machine <b>30</b> authenticates the user. After receiving the request, the first remote machine <b>30</b> validates the request with the ticket authority <b>136</b>. The ticket authority <b>6102</b> then generates a ticket, which includes a first ticket, or client ticket, and a second ticket, or first protocol service ticket. The first and second tickets are “one-time use” tickets having no further value after their first use. In still another embodiment, the first and second tickets must be used within a predetermined time period.

0991In one embodiment, the ticket authority <b>6102</b> stores the first and second tickets in memory (e.g., RAM) until the ticket is used. Alternatively, the ticket authority <b>6102</b> stores the first and second tickets in a storage device (not shown) until the ticket is used. The storage device may include, for example, a database or a persistent memory (e.g., on a floppy disk or hard disk drive). The ticket authority <b>6102</b> subsequently transmits the client ticket to the first remote machine <b>30</b> and the first remote machine <b>30</b> then forwards the client ticket to the client machine <b>10</b>.

0992The client machine <b>10</b> then initiates a communication session with the first protocol service <b>4502</b> by transmitting a proxy connection request over the client-first protocol service communication channel <b>4504</b>. The proxy connection request includes the client ticket. In one embodiment, the proxy connection request also includes a dummy password that can be replaced by the first protocol service <b>4502</b> when establishing a communication session with a remote machine <b>30</b>. In another embodiment, the first remote machine <b>30</b> transmits the dummy password to the client machine <b>10</b> for future generation of a proxy connection request having a format acceptable to the first protocol service <b>4502</b>. The first protocol service <b>4502</b> then extricates the client ticket from the proxy connection request and forwards the client ticket to the ticket authority <b>6102</b> for validation. The ticket authority <b>6102</b> then validates the first ticket. In one embodiment, the ticket authority <b>6102</b> verifies the first ticket by searching its storage device (e.g., database) for the first expected ticket.

0993If the ticket authority <b>6102</b> does not find the first ticket in the storage device (such as if the first ticket has been used already), the ticket authority <b>6102</b> ends the communication session. If the received ticket matches the client ticket that the ticket authority <b>6102</b> expects, the client ticket is validated. The ticket authority <b>6102</b> then transmits the second or first protocol service ticket to the first protocol service <b>4502</b>. Additionally, the ticket authority <b>6102</b> deletes the client ticket from the storage device, as the client ticket has now been used once. In another embodiment, the ticket authority <b>6102</b> also transmits the Internet protocol (IP) address of the remote machine <b>30</b> to the first protocol service <b>4502</b>. In yet another embodiment, the ticket authority <b>6102</b> transmits the domain name of the remote machine <b>30</b> to the first protocol service <b>4502</b> for future conversion into the IP address.

0994The first protocol service <b>4502</b> receives the second ticket, or the first protocol service ticket, and subsequently opens communications across the proxy-server communication channel <b>145</b> by transmitting the second ticket to the remote machine <b>30</b>. The remote machine <b>30</b> receives the first protocol service ticket and then transmits the ticket over a ticket-server communication channel to the ticket authority <b>6102</b> for validation. In one embodiment, if the ticket authority <b>6102</b> determines that the first protocol service ticket received from the remote machine <b>30</b> has been used previously or does not have the correct value (i.e., the same value as the value stored in the associated storage device), the ticket authority <b>6102</b> transmits an error message to the first protocol service <b>4502</b> (or the first remote machine <b>30</b>) to terminate the established communication session with the client machine <b>10</b>. If the ticket authority <b>6102</b> validates the first protocol service ticket, the remote machine <b>30</b> then launches the ICA published application. The remote machine <b>30</b> then transmits application information to the first protocol service <b>4502</b> for remote displaying of the application on the client machine <b>10</b> using the client agent <b>4506</b>.

0995In one embodiment, the client machine <b>10</b> launches the client agent <b>4506</b> when initiating communications with the first protocol service <b>4502</b>. In other embodiments, the client machine <b>10</b> launches the client agent <b>4506</b> when the client machine <b>10</b> receives the application information from the first protocol service <b>4502</b>.

0996Thus, the client machine <b>10</b> is not aware of the first protocol service ticket but only the client ticket. Moreover, the client agent <b>4506</b> cannot access the remote machine <b>30</b> without communicating with the first protocol service <b>4502</b> and presenting the client ticket.

0997The ticket authority <b>6102</b> could also transmit the first protocol service ticket to the first protocol service <b>4502</b> as the user password for the user of the client machine <b>10</b>. This allows the first protocol service <b>4502</b> to use the first protocol service ticket as the login password to gain access to the remote machine <b>30</b> without exposing the user's login password over the untrusted part of the web (i.e., the non-secure client-first protocol service communication channel <b>4504</b>). Thus, in one embodiment, the communications system <b>6100</b> could include a centralized password mapping database managed by the ticket authority <b>6102</b> and co-located with the remote machine <b>30</b> to map the first protocol service ticket with a user's password.

0998Therefore, the password can accompany both tickets (i.e., the first protocol service ticket and the client ticket) or the password can accompany one of the two tickets. As described above, if the password accompanies one of the two tickets, such as the client ticket, then the first protocol service ticket is the password. In one embodiment, the password can be a system password that does not change in value or may be a one-time use password, such as those generated by SecurID tokens developed by RSA Security Inc. of Bedford, Mass.

0999Additionally, the methods described above can be expanded to a communications system having any number of first protocol services <b>4502</b>, or “hops” with which the client machine <b>10</b> has to communicate before establishing a communication session with the remote machine <b>30</b>. Although described in relation to a first protocol service <b>4502</b>, a hop can comprise any network component, such as a proxy, firewall, router, and relay.

1000For instance, a four-hop example is a communication system having a first protocol service <b>4502</b><i>a</i>, a first protocol service <b>4502</b><i>b</i>, and a first protocol service <b>4502</b><i>n</i>, each protocol service including a proxy and located within the demilitarized zone <b>6308</b>. The protocol services <b>4502</b><i>a</i>-<i>n </i>may communicate with each other over a proxy-proxy communication channel. The client machine <b>10</b> communicates with the first protocol service <b>4502</b><i>a </i>which communicates with the second first protocol service <b>4502</b><i>b</i>. In turn, the second first protocol service <b>4502</b><i>b </i>communicates with the third first protocol service <b>4502</b><i>n </i>and then the third first protocol service <b>4502</b><i>n </i>communicates with the remote machine over a proxy-server communication channel <b>4508</b> to establish the communication session with the remote machine. Furthermore, although the embodiment described above includes a ticket having a client ticket and a first protocol service ticket, another embodiment includes the ticket comprising numerous tickets.

1001In still another embodiment of a network communications system <b>6100</b> as shown in <figref idref="DRAWINGS">FIG. 62</figref>, an ACR Service <b>5002</b> can be used instead of the ticket authority <b>6102</b> for reconnecting the client machine <b>10</b> to any of the host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. In this embodiment, the ACR Service <b>5002</b> can provide similar services as described above with regards to the ticket authority <b>6102</b>. As previously described, the ACR Service <b>5002</b> generates, validates and manages a SID and a key for connecting and reconnecting a client communication session. A SID and a key can form a ticket as in the type of ticket generated, validated and managed by the ticket authority <b>6102</b> as described above. As such, in another embodiment, a ticket may be used interchangeably for the combination of a session identifier and a key.

1002The intermediary machine <b>30</b>, as shown in <figref idref="DRAWINGS">FIG. 62</figref>, is configured to communicate with the ACR Service <b>5002</b>. In one embodiment, the ACR Service <b>5002</b> is configured to receive a request for a first SID and a first key from the intermediary machine <b>30</b> and to thereafter generate the first SID and first key. The ACR Service <b>5002</b> uses the first SID to identify the communication session that is established between the client machine <b>10</b> and a host service <b>4516</b>. The first SID and the first key allow the client machine <b>10</b> to automatically reconnect with the host service <b>4516</b> after an abnormal disruption of service without requiring the client machine <b>10</b> to provide authentication credentials again.

1003After generation of the first SID and the first key, the ACR Service <b>5002</b> encrypts the authentication credentials supplied by the client machine <b>10</b> using the first key so that an attacker who gains access to the intermediary machine <b>30</b> or the ACR Service <b>5002</b> cannot access the authentication credentials without the first key. The ACR Service <b>5002</b> then stores the encrypted authentication credentials with the SID in memory <b>5018</b> and transmits the first SID and the first key to the client machine <b>10</b> over the network <b>150</b>. Upon the client's receipt of the SID and the key, the ACR Service <b>5002</b> destroys (i.e., deletes) the key from its memory <b>5018</b>.

1004In another embodiment, the first protocol service <b>4502</b> is configured to generate a second SID and second key. The first protocol service <b>4502</b> can also be configured to transmit the second SID and second key to the client machine <b>10</b>, while keeping a copy of the second SID and second key. The copy of the second SID and second key can later be used by the first protocol service <b>4502</b> to validate the second SID and second key originally transmitted to the client machine <b>10</b> when it is later presented to the first protocol service <b>4502</b> during the process of reconnecting the client machine <b>10</b>. In one embodiment, the first protocol service <b>4502</b> transmits the second SID and second key to the client machine <b>10</b> via the intermediary machine <b>30</b>. In another embodiment, the first protocol service <b>4502</b> transmits the second SID and second key to the client machine <b>10</b> directly. Moreover, as described in greater detail below, the first protocol service <b>4502</b> can be further configured to delete, during the process of reconnecting the client machine <b>10</b> to a host service <b>4516</b>, the second SID and second key, and thereafter generate a replacement second SID and second key. Additionally, in another embodiment, the second SID and second key is configured for automatic deletion after a pre-determined period of time.

1005In one embodiment, the intermediary machine <b>30</b> serves as an intermediary for the first and second SIDs and keys. The intermediary machine <b>30</b> receives, for example, the first SID and first key generated by the ACR Service <b>5002</b> and the second SID and second key generated by the first protocol service <b>4502</b>. The intermediary machine <b>30</b> can then transmit the first SID and first key and the SID and second key to the client machine <b>10</b>. Moreover, during the process of reconnecting the client machine <b>10</b> to a host service <b>4516</b>, the intermediary machine <b>30</b> can accept the first SID and first key and the second SID and second key from the client machine <b>10</b> and thereafter transmit the first SID and first key to the ACR Service <b>5002</b> and, if appropriate, the second SID and second key t to the first protocol service <b>4502</b>.

1006If the first communication session between the client machine <b>10</b> and the host service <b>4516</b> terminates, for example abnormally, the new session can be re-established without requiring the user to reenter his or her authentication credentials. When the client machine <b>10</b> and the host service <b>4516</b> re-establish a second communication session, the client machine <b>10</b> transmits the first and second SIDs and keys to the intermediary machine <b>30</b>. The intermediary machine <b>30</b> transmits the first SID and first key to the ACR Service <b>5002</b>, which uses the SID to locate and retrieve the encrypted authentication credentials for the first connection and uses the first key to decrypt the retrieved authentication credentials. The ACR Service <b>5002</b> then authenticates the client by validating the decrypted authentication credentials. After re-authentication, the second SID and second key is forwarded to the first protocol service <b>4502</b> to re-establish the second connection <b>4508</b> with the host service <b>4516</b>.

1007Referring to <figref idref="DRAWINGS">FIG. 63</figref>, another embodiment of a system <b>4500</b> for network communications includes the networks <b>150</b> and <b>150</b>′, the client machine <b>10</b>, the first protocol service <b>4502</b>, the host services <b>4516</b>, the intermediary machine <b>30</b>, and the ticket authority <b>6102</b>, as described above, and further depicts a first remote machine <b>30</b> and a second remote machine <b>30</b>, both of which are used, in one embodiment, for initially connecting the client machine <b>10</b> to a host service <b>4516</b>. Moreover, in the embodiment of <figref idref="DRAWINGS">FIG. 63</figref>, the client machine <b>10</b> further includes a web browser <b>6302</b>, such as, for example, the INTERNET EXPLORER program from Microsoft Corporation of Redmond, Wash., to connect to the World Wide Web.

1008In one embodiment (not shown), the system <b>4500</b> includes two or more intermediary machines <b>30</b> and/or two or more first protocol services <b>4502</b>. The intermediary machine <b>30</b>, through which messages between the client machine <b>10</b> and the first protocol service <b>4502</b> must pass, and/or the first protocol service <b>4502</b> can, as explained below, each be chosen based on, for example, a load balancing equation.

1009Each of the first remote machine <b>30</b> and the second remote machine <b>30</b> can be any computing device that is capable of communication and that has sufficient processor power and memory capacity to perform the operations described herein. For example, in one embodiment, the first remote machine <b>30</b> is a web server, providing one or more websites or web based applications. In another embodiment, the second remote machine <b>30</b> provides an XML service or web service.

1010In one embodiment, the client machine <b>10</b> and the network <b>150</b> form an external network <b>6304</b>, separated from the rest of the system <b>6100</b> by a first firewall <b>6306</b>, depicted as a dashed line. The intermediary machine <b>30</b> and the first remote machine <b>30</b> can be located in a “demilitarized zone” <b>6308</b> (i.e., a network region placed between a company's private network and the public network), separated from the rest of the system <b>4500</b> by the first firewall <b>6306</b> and a second firewall <b>6310</b>, also depicted by a dashed line. In some embodiments, the first firewall <b>6306</b> and the second firewall <b>6310</b> prohibit unauthorized communications to or from the remote machines <b>30</b>. Then, as shown, the network <b>150</b>′, the first protocol service <b>4502</b>, the host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>, the ticket authority <b>6102</b>, and the second remote machine <b>30</b>, form an internal network <b>6312</b>, separated from the rest of the system <b>4500</b> by the second firewall <b>6310</b>.

1011In some embodiments, the demilitarized zone <b>6308</b> includes a ticket protocol service <b>6314</b> (shown in shadow in <figref idref="DRAWINGS">FIG. 63</figref>), comprising a proxy (not shown), and the first remote machine <b>30</b>, which may be a web server. The proxy may comprise a security gateway through which messages over the client-first protocol service communication channel <b>4504</b> pass. In one embodiment, the network firewall <b>6306</b> repudiates any incoming message from the client-first protocol service communication channel <b>4504</b> that does not have the first protocol service <b>4502</b> as its destination. Likewise, the network firewall <b>6306</b> repudiates any outgoing message for the client-first protocol service communication channel <b>4504</b> unless its source is the first protocol service <b>4502</b>. The security gateway can alternatively be a router, firewall, relay, or any network component that can provide the necessary security. The proxy may also be a network component separate from the first protocol service <b>4502</b> that may run on the same computing device of the first protocol service <b>4502</b> or on a different computing device. In some embodiments, the proxy is an intermediary for securely passing communications between the client machine <b>10</b> and the first protocol service <b>4502</b>.

1012Alternatively, in another embodiment not shown in <figref idref="DRAWINGS">FIG. 63</figref>, the system <b>4500</b> further includes a third remote machine <b>30</b> positioned, in the demilitarized zone <b>6308</b>, between the network <b>150</b> and the intermediary machine <b>30</b>. The third remote machine <b>30</b> can be any computing device that is capable of networked communication and that has sufficient processor power and memory capacity to perform the operations described herein. As described below, the third remote machine <b>30</b> is used, in some embodiments, during the process of initially connecting the client machine <b>10</b> to a host service <b>4516</b> and/or during the process of reconnecting the client machine <b>10</b> to a host service <b>4516</b>. More specifically, as described below, where the system <b>4500</b> includes two or more intermediary machines <b>30</b>, the third remote machine <b>30</b> can, based on a load balancing equation for example, choose the intermediary machine <b>30</b> through with communications between the client agent <b>4506</b> of the client machine <b>10</b> and the first protocol service <b>4502</b> must pass.

1013Moreover, referring to <figref idref="DRAWINGS">FIG. 63</figref>, the intermediary machine <b>30</b>, in an alternative embodiment, can be replaced by two or more levels “a”-“n” of intermediary machines <b>30</b>. As illustrated, each level “a”-“n” can include two or more intermediary machines <b>30</b>′. As described below, the client agent <b>4506</b> of the client machine <b>10</b> can be routed through any combination of the intermediary machines <b>30</b> based on, for example, load balancing equations. For example, as illustrated, the client agent <b>4506</b> can be routed through the intermediary machines <b>30</b> via connection <b>4504</b>. For additional security, each of the “hops” via connection <b>4504</b> may require a ticket or re-connection ticket for validating and authenticating the multiple-hop connection between the client machine <b>10</b> and the host service <b>4516</b>. Other configurations of the system <b>4500</b>, as would be readily apparent to one skilled in the art, are also possible.

1014Referring again to <figref idref="DRAWINGS">FIG. 63</figref>, in one embodiment, the web browser <b>6302</b> communicates over the network <b>150</b> with the first remote machine <b>30</b>, which itself interfaces with the second remote machine <b>30</b> and the ticket authority <b>6102</b>. More specifically, the first remote machine <b>30</b> is configured with the address of the second remote machine <b>30</b> and the ticket authority <b>6102</b>. In one embodiment, as explained further below, the first remote machine <b>30</b> is configured to relay information between, and thereby prevent direct communication between, the web browser <b>6302</b> of the client machine <b>10</b>, the second remote machine <b>30</b>, and the ticket authority <b>6102</b>. By preventing such direct communication, the first remote machine <b>30</b> adds an additional level of security to the system <b>4500</b>. The first remote machine <b>30</b> can also be configured with the address of the intermediary machine <b>30</b>, or, alternatively, with the address of two or more intermediary machines <b>30</b>.

1015For its part, the second remote machine <b>30</b> is configured to determine which of the application programs running on the host services <b>4516</b> are available to a user of the client machine <b>10</b>. In other words, the second remote machine <b>30</b> is configured to determine which of the application programs the user is authorized to access. In one embodiment, after the user selects his desired application program, as described further below, the second remote machine <b>30</b> is further configured to determine which of the host services <b>4516</b> will be used to run the user's desired application for purposes of load balancing. The second remote machine <b>30</b> returns the address of that host service <b>4516</b> to the first remote machine <b>30</b>. The second remote machine <b>30</b> also returns the address of the first protocol service <b>4502</b>, which can also be selected from amongst a plurality of first protocol services <b>4502</b> through the use of a load balancing equation, to the first remote machine <b>30</b>. In turn, the first remote machine <b>30</b> transmits the address of the chosen first protocol service <b>4502</b> and the chosen host service <b>4516</b> to the ticket authority <b>6102</b>.

1016For its part, the ticket authority <b>6102</b> generates connection tickets. In one embodiment, the ticket authority <b>6102</b> transmits an initial connection ticket to the first remote machine <b>30</b> for transmission to the client machine <b>10</b>. In another embodiment, the ticket authority transmits a first reconnection ticket to the intermediary machine <b>30</b>.

1017In one embodiment, the ticket authority <b>6102</b> issues one or more tickets to authenticate the client machine <b>10</b>. In particular, the ticket authority <b>6102</b> enables authentication of the client machine <b>10</b> over one communication channel (i.e., a client-web server communication channel) based on authentication credentials. The ticket authority <b>6102</b> further enables the client machine <b>10</b> to be authenticated to another communication channel (i.e., the client-first protocol service communication channel <b>4504</b>) without having the client machine <b>10</b> repeatedly provide authentication credentials on the other communication channel.

1018In one embodiment, the ticket authority <b>6102</b> is a stand-alone network component. In other embodiments, a modular ticket authority <b>136</b> is a software module residing on one or more remote machines <b>30</b>. For example, there may be a ticket authority <b>6102</b> for each of the remote machines <b>30</b>. In some embodiments, a first remote machine <b>30</b>, such as a web server in the demilitarized zone <b>6308</b>, may communicate with the ticket authority <b>6102</b> and/or the remote machine <b>30</b> over an agent-server communication channel. In another embodiment, the ticket authority <b>6102</b> may reside on an intermediary remote machine <b>30</b> separate from other remote machines <b>30</b>.

1019In one embodiment, the ticket authority <b>6102</b> generates a first ticket and a second ticket. In some embodiments, the tickets are both nonces. In further embodiments, the tickets are generated using a cryptographic random number generator that has been suitably seeded with randomness. The first ticket is transmitted to the client machine <b>10</b> and is used to establish a first communication session between the client machine <b>10</b> and the first protocol service <b>4502</b>. The second ticket is transmitted to the first protocol service <b>4502</b> and is used to establish a second communication session between the first protocol service <b>4502</b> and a remote machine <b>30</b>.

1020In some embodiments, the first remote machine <b>30</b> is a web server. In one of these embodiments, the first remote machine <b>30</b> delivers web pages to the client machine <b>10</b>. In another of these embodiments, the first remote machine <b>30</b> is capable of establishing a secure client-web server communication channel with the client machine <b>10</b>.

1021In other embodiments, the first remote machine <b>30</b> is a web server providing a corporate portal, also referred to as an enterprise information portal, to the client machine <b>10</b>. In one of these embodiments, enterprise portals are company web sites that aggregate, personalize and serve applications, data and content to users, while offering management tools for organizing and using information more efficiently. In other embodiments, the first remote machine <b>30</b> provides a web portal, or Internet portal, to the client machine <b>10</b>. A web portal is similar to a corporate portal but typically does not include business-specific information.

1022In one embodiment, a user of the client machine <b>10</b> employs the web browser <b>6302</b> to authenticate the user to the first remote machine <b>30</b>. In one embodiment, the client machine <b>10</b> transmits user credentials, such as login and password information, to the first remote machine <b>30</b>. The first remote machine <b>30</b> verifies that the user has access to the machine farm <b>38</b>.

1023In a further embodiment, the web browser <b>6302</b> uses SSL to establish a secure client-web server communication channel. The web browser <b>6302</b> can alternatively connect to the first remote machine <b>30</b> over a client-web server communication channel using other security protocols, such as, but not limited to, Secure Hypertext Transfer Protocol (SHTTP) developed by Terisa Systems of Los Altos, Calif., HTTP over SSL (HTTPS), Private Communication Technology (PCT) developed by Microsoft Corporation of Redmond, Wash., and the Transport Level Security (TLS) standard promulgated by the Internet Engineering Task Force (IETF). In one embodiment, the first remote machine <b>30</b> transmits a web portal or enterprise portal, as described above, to the client machine <b>10</b> upon validation of the user to enable the client machine <b>10</b> to request a resource, such as, for example, an application or a server desktop to be remotely displayed on the client machine <b>10</b>.

1024The client-web server communication channel may be any secure communication channel. In some embodiments, communications over the channel are encrypted. In certain of these embodiments, the client machine <b>10</b> and the first remote machine <b>30</b> may communicate using the Secure Socket Layer (SSL) of the HyperText Transfer Protocol (HTTPS). Alternatively, the client machine <b>10</b> and the first remote machine <b>30</b> may use other encryption techniques, such as symmetric encryption techniques, to protect communications.

1025Further, in one embodiment the client-first protocol service communication channel <b>4502</b> can be established by using, for example, a presentation services protocol such as ICA, X11 protocol, VNC, or RDP. Although described as establishing a first communication session between the client machine <b>10</b> and the first protocol service <b>4502</b> and a second communication session between the first protocol service <b>4502</b> and the remote machine <b>30</b>, the communication session can be viewed as a single, logical communication session between the client machine <b>10</b> and the host service <b>4516</b>.

1026In another embodiment of a network communication system <b>4500</b> as shown in <figref idref="DRAWINGS">FIG. 64</figref>, the ACR Service <b>5002</b> can be used instead of the ticket authority <b>6102</b> to reconnect a client machine <b>10</b> to a host service <b>4516</b>. Instead of using tickets as with the ticket authority <b>6102</b>, the ACR Service <b>5002</b> generates, validates and manages SIDs and keys for connecting and reconnecting client communication sessions. The ACR Service <b>5002</b> authenticates and re-authenticates the client to a host service <b>4516</b> or remote machine <b>30</b> using a SID and key, or a ticket, associated with the client machine <b>10</b>. As previously mentioned, a ticket can be used to refer to the combination of a SID and key or a ticket can comprise a SID and a key.

1027The system <b>4500</b> of <figref idref="DRAWINGS">FIG. 64</figref> includes the networks <b>150</b> and <b>150</b>′, the client machine <b>10</b>, the first protocol service <b>4502</b>, the host services <b>4516</b>, the intermediary machine <b>30</b>, and the ACR Service <b>5002</b>, as described above, and further depicts a first remote machine <b>30</b> and a second remote machine <b>30</b>, both of which are used, in one embodiment, for initially connecting the client machine <b>10</b> to a host service <b>4516</b>. Moreover, the client machine <b>10</b> further includes a web browser <b>6302</b> to connect to the World Wide Web.

1028In one embodiment (not shown), the system <b>4500</b> includes two or more intermediary machines <b>30</b> and/or two or more first protocol services <b>4502</b> or two or more ACR Services <b>5002</b>. The intermediary machine <b>30</b>, through which messages between the client machine <b>10</b> and the first protocol service <b>4502</b> must pass, and/or the first protocol service <b>4502</b> can and/or the ACR Service <b>5002</b>, as explained below, each be chosen based on, for example, a load balancing equation.

1029In another embodiment, the system <b>4500</b> of <figref idref="DRAWINGS">FIG. 64</figref> can include an external network <b>6304</b>, separated from a “demilitarized zone” <b>6308</b> by a first firewall <b>6306</b> which in turn is separated from an internal network <b>6312</b> by a second firewall <b>6310</b>. Although the invention is discussed above in terms of various network topologies in <figref idref="DRAWINGS">FIGS. 63 and 64</figref>, any other network topologies can be used, such as for example, a topology including combinations of internal networks, external networks, sub-networks, intranets, firewalls, security zones, single servers, a server network or server farms.

1030Alternatively, in another embodiment not shown in <figref idref="DRAWINGS">FIG. 64</figref>, the system <b>4500</b> further includes a third remote machine <b>30</b> positioned, in the demilitarized zone <b>6308</b>, between the network <b>150</b> and the intermediary machine <b>30</b>. The third remote machine <b>30</b> is used, in some embodiments, during the process of initially connecting the client machine <b>10</b> to a host service <b>4516</b> and/or during the process of reconnecting the client machine <b>10</b> to a host service <b>4516</b>.

1031In another embodiment of the system <b>4500</b> in <figref idref="DRAWINGS">FIG. 64</figref>, the intermediary machine <b>30</b>, can be replaced by two or more levels “a”-“n” of intermediary machines <b>30</b>′. The client agent <b>4506</b> of the client machine <b>10</b> can be routed through any combination of the intermediary machines <b>30</b> based on, for example, load balancing equations.

1032In one embodiment, the web browser <b>6302</b> communicates over the network <b>150</b> with the first remote machine <b>30</b>, which itself interfaces with the second remote machine <b>30</b> and the ACR Service <b>5002</b>. The first remote machine <b>30</b> is configured with the address of the second remote machine <b>30</b> and the ACR Service <b>5002</b>. In another embodiment to provide an additional level of security in the system <b>4500</b>, the first remote machine <b>30</b> is configured to relay information between, and thereby prevent direct communication between, the web browser <b>6302</b> of the client machine <b>10</b>, the second remote machine <b>30</b>, and the ACR Service <b>5002</b>. The first remote machine <b>30</b> can also be configured with the address of any of the intermediary machines <b>30</b>′.

1033For its part, the second remote machine <b>30</b> is configured to determine which of the application programs running on the host services <b>4516</b> are available to a user of the client machine <b>10</b> and to provide the address of the host service <b>4516</b> selected by the user to the first remote machine <b>30</b>. The second remote machine <b>30</b> also provides the address of one of the multiple first protocol service <b>4502</b>, through the use of a load balancing equation, to the first remote machine <b>30</b>. In turn, the first remote machine <b>30</b> transmits the address of the chosen first protocol service <b>4502</b> and the chosen host service <b>4516</b> to the ACR Service <b>5002</b>.

1034For its part, the ACR Service <b>5002</b> generates, validates and manages connection SIDs and key to provide authentication and re-authentications services to re-establish a client's communication session with a host service <b>4516</b> or remote machine <b>30</b>, as described herein. In one embodiment, the ACR Service <b>5002</b> transmits a first SID and first key to the first remote machine <b>30</b> for transmission to the client machine <b>10</b>. In another embodiment, the ACR Service <b>5002</b> transmits a first SID and first key to one of the intermediary machines <b>30</b>.

1035In other embodiments, methods for network communications enable reconnecting a client machine <b>10</b> to a host service <b>4516</b> using a plurality of secondary protocols encapsulated within a first protocol. The method includes establishing a first connection between a client machine <b>10</b> and a first protocol service <b>4502</b> using a first protocol and communicating between the client machine <b>10</b> and the first protocol service <b>4502</b> via a plurality of second protocols encapsulated within the first protocol. Moreover, at least one of the second protocols includes a plurality of virtual channels.

1036In one embodiment of this aspect of the invention, a second connection is established between the first protocol service <b>4502</b> and a host service <b>4516</b> using one of the secondary protocols. Communication between the first protocol service <b>4502</b> and the host service <b>4516</b> occurs via one of the secondary protocols. Specifically, each of the plurality of second connections is established between the first protocol service <b>4502</b> and a different host service <b>4516</b> and each of the plurality of second connections is established using one of the plurality of secondary protocols. In yet another embodiment, the first connection between the client machine <b>10</b> and the first protocol service <b>4516</b> is established through one or more intermediary machines <b>30</b>.

1037Referring now to <figref idref="DRAWINGS">FIG. 65</figref>, one embodiment of a method <b>6500</b> for reconnecting a client to a host service after a network failure is illustrated. At step <b>6502</b>, the client machine <b>10</b> initially connects to one of a plurality of host services <b>4516</b>. Generally, the client machine <b>10</b> is required to transmit authentication credentials to the host service <b>4516</b> to initiate the communication session. After the client machine <b>10</b> is connected to the host service <b>4516</b>, the client machine <b>10</b> and the host service <b>4516</b> communicate, through the first protocol service <b>4502</b>, and at step <b>6504</b>, via a plurality of secondary protocols encapsulated within the first protocol as discussed above in reference to <figref idref="DRAWINGS">FIGS. 47-48</figref> and <figref idref="DRAWINGS">FIG. 49</figref>. In one embodiment, the first protocol service <b>4502</b> encrypts, prior to the transmission of any first protocol packets, communications at the level of the first protocol <b>4704</b>, thereby securing the communications. In another embodiment, the first protocol service <b>4502</b> compresses, prior to the transmission of any first protocol packets, the communications at the level of the first protocol, thereby improving communication efficiency.

1038At step <b>6506</b>, the client agent <b>4506</b> determines whether the connection <b>4504</b> between the client agent <b>4506</b> and the first protocol service <b>4502</b> has failed. For example, the connection <b>4504</b><i>a </i>between the client agent <b>4506</b> and the intermediary machine <b>30</b> may have failed, the connection <b>4504</b><i>b </i>between the intermediary machine <b>30</b> and the first protocol service <b>4502</b> may have failed, or both the connection <b>4504</b><i>a </i>and the connection <b>4504</b><i>b </i>may have failed. If the client agent <b>4506</b> determines that the connection <b>4504</b> has not failed, the method <b>6500</b> proceeds to step <b>6508</b>. If, on the other hand, the client agent <b>4506</b> determines that the connection <b>4504</b> has failed, the client machine <b>10</b> is, at step <b>6510</b>, reconnected to the host service <b>4516</b>.

1039The step of reconnecting in step <b>6510</b> after a first communication session ends abnormally, can comprise in a system <b>4500</b> deploying a ticket authority <b>6102</b> and the client machine <b>10</b> transmitting the SID and the first and second reconnection tickets to the intermediary machine <b>30</b>. The intermediary machine <b>30</b> uses the first reconnection ticket to authenticate the client machine <b>10</b> and re-establish the connection <b>4504</b> between the client machine <b>10</b> and the intermediate node <b>30</b>′. The intermediary machine <b>30</b> then transmits the second reconnection ticket to the first protocol service <b>4502</b>, which uses the second reconnection ticket to authenticate re-establish the connection <b>4508</b> to the host service <b>4516</b>. The reconnection tickets thus allow the client machine <b>10</b> to automatically establish a second communication session to the host service <b>4516</b> without retransmitting the authentication credentials a second time.

1040In another embodiment, the step of reconnecting, in step <b>6510</b>, can also comprise a system <b>4500</b> deploying an ACR Service <b>5002</b>. In such an embodiment, the client machine <b>10</b> transmits a first SID and first key to the intermediary machine <b>30</b> to authenticate the client machine <b>10</b> and reestablish the connection of the client machine <b>10</b> to the host service <b>4516</b>.

1041It is determined, at step <b>6508</b>, whether the client machine <b>10</b> wishes to cleanly terminate its connection <b>4504</b> with the first protocol service <b>4502</b> and, consequently, its connections <b>4508</b><i>a</i>-<b>4508</b><i>n </i>with the host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>. If not, communication between the client machine <b>10</b> and the first protocol service <b>4502</b>, via the plurality of secondary protocols encapsulated within the first protocol, continues at step <b>6504</b>. If so, then, at step <b>6512</b>, all connections <b>4504</b><i>a</i>, <b>4504</b><i>b</i>, and <b>4508</b><i>a</i>-<b>4508</b><i>n </i>are broken and all reconnection tickets are deleted. In another embodiment using an ACR Service <b>5002</b>, at step <b>6512</b>, all connections <b>4504</b><i>a</i>, <b>4504</b><i>b</i>, and <b>4508</b><i>a</i>-<b>4508</b><i>n </i>are broken and all SIDS and keys are deleted. In one embodiment, the intermediary machine <b>30</b> uses a handle it receives from the ticket authority <b>6102</b> to delete a copy of a first reconnection ticket kept at the ticket authority <b>6102</b>. In another embodiment deploying a ticket authority <b>6102</b>, the first protocol service <b>4502</b> deletes a copy of a second reconnection ticket kept at the first protocol service <b>4502</b>. In yet another embodiment deploying the ACR Service <b>5002</b>, the first protocol service <b>4502</b> deletes a copy of a second SID and second key kept at the first protocol service <b>4502</b>.

1042In a further embodiment using a ticket authority <b>6102</b>, if for some reason a secondary protocol connection <b>4508</b> fails, a copy of the second reconnection ticket associated therewith and kept at the first protocol service <b>4502</b> is deleted by the first protocol service <b>4502</b>. In yet another embodiment, a first reconnection ticket and/or a second reconnection ticket is automatically deleted after a pre-determined period of time following a failure in the connection <b>4504</b>, as at step <b>6506</b>, and/or following a clean termination of the connection <b>4504</b>, as at step <b>6508</b>.

1043In another aspect, this invention relates to methods for reconnecting the client machine <b>10</b> to the host service <b>4516</b> using the ACR Service <b>5002</b>. Referring now to <figref idref="DRAWINGS">FIG. 66</figref>, one embodiment of step <b>6510</b> in <figref idref="DRAWINGS">FIG. 65</figref> is illustrated. The client machine <b>10</b> transmits the first SID and the first key to the ACR Service <b>5002</b> to reconnect to the host service (step <b>6602</b>). The ACR Service <b>5002</b> uses the SID (step <b>6604</b>) to locate and retrieve the encrypted authentication credentials and uses the key (step <b>6606</b>) to decrypt the retrieved authentication credentials. In one embodiment (not shown), the ACR Service <b>5002</b> uses the decrypted authentication credentials to re-authenticate the client machine <b>10</b> to the maintained session between the first protocol service <b>4502</b> and the host service <b>4516</b>. After re-authenticating, the reestablished connection of the client machine <b>10</b> to the first protocol service <b>4516</b> is re-linked to the maintained session between the first protocol service <b>4502</b> and the host service <b>4516</b>.

1044In another embodiment, during the second communication session, the ACR Service <b>5002</b> generates (step <b>6608</b>) a second key for the authentication credentials and then encrypts (step <b>6610</b>) the authentication credentials using the second key. The ACR Service <b>5002</b> creates a second SID (step <b>6612</b>). Then the decrypted authentication credentials are re-authenticated with the host service <b>4516</b> and the second SID is associated with the maintained communication session with the host service <b>4516</b> (step <b>6612</b><i>a</i>). The ACR Service <b>5002</b> then transmits the second SID and second key to the client machine <b>10</b> (step <b>6614</b>). In one embodiment, the ACR Service <b>5002</b> may transmit the second SID and second key through an intermediary machine <b>30</b>. The client machine <b>10</b> stores the second SID and second key (step <b>6616</b>). The ACR Service <b>5002</b> then deletes the second key (step <b>6618</b>).

1045Referring to <figref idref="DRAWINGS">FIGS. 67-68</figref>, one embodiment of a method <b>6700</b> for initially connecting the client machine <b>10</b> to the host service <b>4516</b> using an ACR Service <b>5002</b> is illustrated. At step <b>6702</b>, the client machine <b>10</b>, using the browser <b>6302</b>, sends a request, such as, for example, an HTTP request, to the first remote machine <b>30</b>. The first remote machine <b>30</b> returns a web page, such as, for example, an HTML form requesting authentication information (e.g., a username and a password). A user of the client machine <b>10</b> enters his authentication credentials and transmits the completed form to the first remote machine <b>30</b>.

1046The first remote machine <b>30</b>, at step <b>6704</b>, then informs the user of the client machine <b>10</b> of applications available for execution. In one embodiment, the first remote machine <b>30</b> extracts the user's credentials from the login page and transmits them to the second remote machine <b>30</b>, together with a request for the second remote machine <b>30</b> to enumerate the applications available to the user. Based on the user's credentials, the second remote machine <b>30</b> returns a list of specific applications available to the first remote machine <b>30</b>, which then forwards the list, in the form of a web page for example, to the user of the client machine <b>10</b>.

1047At step <b>6706</b>, the user selects the desired application and a request for that application is sent to the first remote machine <b>30</b>. For example, in one embodiment, the user clicks on a desired application listed in the web page presented to him by the first remote machine <b>30</b> and an HTTP request for that application is forwarded to the first remote machine <b>30</b>. The request is processed by the first computing node <b>140</b> and forwarded to the second remote machine <b>30</b>.

1048At step <b>6708</b>, the second remote machine <b>30</b> determines the host service <b>4516</b> on which the desired application will be executed. The second remote machine <b>30</b> can make that determination based, for example, on a load balancing equation. In one embodiment, the second remote machine <b>30</b> also determines a first protocol service <b>4502</b> from amongst a plurality of first protocol services <b>4502</b> that will be used to communicate with the host service <b>4516</b> via a connection <b>4508</b>. Again, the second remote machine <b>30</b> can make that determination based, for example, on a load balancing equation. The second remote machine <b>30</b> returns the address of the chosen host service <b>4516</b> and the chosen first protocol service <b>4502</b> to the first remote machine <b>30</b>.

1049The client machine <b>10</b>, at step <b>6710</b>, is then provided with an initial connection session id and key, a first SID and first key, and an address for the intermediary machine <b>30</b> (which is either its actual address or its virtual address, as described below). In one embodiment, the first remote machine <b>30</b> provides the address for the chosen host service <b>4516</b> and the chosen first protocol service <b>4502</b> to the ACR Service <b>5002</b>, together with a request for the initial connection session id and key. The ACR Service <b>5002</b> generates the initial session id and key, and transmits the session id and key to the first remote machine <b>30</b>, while keeping a copy for itself.

1050In some embodiments, the ticket authority <b>6102</b> generates an initial connection ticket. In one of these embodiments, the ticket authority <b>6102</b> keeps the address of the chosen host service <b>4516</b> and the chosen first protocol service <b>4502</b>, generates the initial connection ticket, and transmits the initial connection ticket to the first remote machine <b>30</b>, while keeping a copy for itself. In one embodiment, the ticket authority <b>6102</b>, in response to the request for the initial connection ticket by the first remote machine <b>30</b>, generates connection tickets for each of the “hops” between the client machine <b>10</b> and the host service <b>4516</b>. In another embodiment, the first remote machine <b>30</b> requests initial connection tickets for each of the “hops” either in a single request or in multiple requests.

1051The first remote machine <b>30</b>, configured, in one embodiment, with the actual address of the intermediary machine <b>30</b>, then transmits the actual address of the intermediary machine <b>30</b> and the initial connection session id and key to the browser <b>6302</b> of the client machine <b>10</b>. In some embodiments, an initial connection ticket is transmitted. The first remote machine <b>30</b> can, for example, first create a file containing both the actual address of the intermediary machine <b>30</b> and the initial connection ticket and then transmitting the file to the browser <b>6302</b> of the client machine <b>10</b>. Optionally, in another embodiment, the first remote machine <b>30</b> is configured with the actual address of two or more intermediary machines <b>30</b>. In such an embodiment, the first remote machine <b>30</b> first determines the intermediary machine <b>30</b> through which messages between the client machine <b>10</b> and the first protocol service <b>4502</b> will have to pass. The first remote machine <b>30</b> then transmits the actual address of that chosen intermediary machine <b>30</b> and the initial connection ticket to the browser <b>6302</b> of the client machine <b>10</b> using, for example, the file described above. In one embodiment, the first remote machine <b>30</b> chooses the intermediary machine <b>30</b> using a load balancing equation. The client agent <b>4506</b> of the client machine <b>10</b> is then launched and uses the address of the intermediary machine <b>30</b>, to establish, at step <b>6712</b>, a first protocol connection <b>4504</b><i>a </i>between the client agent <b>4506</b> of the client machine <b>10</b> and the intermediary machine <b>30</b>.

1052Alternatively, in another embodiment, the first remote machine <b>30</b> is configured with an actual address of the third remote machine <b>30</b>, which serves as a virtual address of an intermediary machine <b>30</b>. In such an embodiment, the first remote machine <b>30</b> transmits, at step <b>6710</b>, the actual address of the third remote machine <b>30</b> and the initial connection session id and key to the browser <b>6302</b> of the client machine <b>10</b> using, for example, the file described above. The client agent <b>4506</b> of the client machine <b>10</b> is then launched and uses the actual address of the third remote machine <b>30</b> to establish, at step <b>6712</b>, a first protocol connection between the client agent <b>4506</b> of the client machine <b>10</b> and the third remote machine <b>30</b>. The third remote machine <b>30</b> then determines the intermediary machine <b>30</b> through which messages between the client machine <b>10</b> and the first protocol service <b>4502</b> will have to pass. In one embodiment, the third remote machine <b>30</b> chooses the intermediary machine <b>30</b> using a load balancing equation. Having chosen the intermediary machine <b>30</b>, the third remote machine <b>30</b> establishes a first protocol connection to the intermediary machine <b>30</b>. A first protocol connection <b>4504</b><i>a </i>therefore exists, through the third remote machine <b>30</b>, between the client agent <b>4506</b> of the client machine <b>10</b> and the intermediary machine <b>30</b>. The actual address of the third remote machine <b>30</b> is therefore mapped to the actual address of the intermediary machine <b>30</b>. To the client agent <b>4506</b> of the client machine <b>10</b>, the actual address of the third remote machine <b>30</b> therefore serves as a virtual address of the intermediary machine <b>30</b>.

1053In one embodiment, where more than one level of intermediary machines <b>30</b>′ exist, as described above, the first remote machine <b>30</b> or the third remote machine <b>30</b>, respectively, only choose the intermediary machine <b>30</b> to which the client agent <b>4506</b> will connect at level “a.” In such an embodiment, at each of the levels “a”-“n−1”, the intermediary machine <b>30</b> through which the client agent <b>4506</b> is routed at that level thereafter determines, based on a load balancing equation for example, the intermediary machine <b>30</b> to which it will connect at the next level. Alternatively, in other embodiments, the first remote machine <b>30</b> or the third remote machine <b>30</b>, respectively, determine, for more than one or all of the levels “a”-“n”, the intermediary machines <b>30</b> through which the client agent <b>4506</b> will be routed.

1054Having established the first protocol connection <b>4504</b><i>a </i>between the client agent <b>4506</b> of the client machine <b>10</b> and the intermediary machine <b>30</b>, for example the intermediate node <b>30</b>′ at level “n” (hereinafter referred to in method <b>6700</b> as the intermediary machine <b>30</b>), the client agent <b>4506</b> then transmits the initial connection ticket to the intermediary machine <b>30</b>.

1055It is then determined, at step <b>6714</b>, whether the initial connection SID and key is valid. In one embodiment, the intermediary machine <b>30</b> transmits the initial connection SID and key to the ACR Service <b>5002</b> for validation. In one embodiment, the ACR Service <b>5002</b> validates the SID and key by comparing it to the copy of the SID and encrypted authentication credentials it kept at step <b>6710</b>. If the ACR Service <b>5002</b> determines the SID and key to be valid, the ACR Service <b>5002</b> transmits, at step <b>6802</b> (<figref idref="DRAWINGS">FIG. 68</figref>), the address of the first protocol service <b>4502</b> and the address of the chosen host service <b>4516</b> to the intermediary machine <b>30</b>. The first protocol service <b>4502</b> can also delete the SID and key and any copy thereof. If, on the other hand, the ACR Service <b>5002</b> determines the SID and key to be invalid, the client machine <b>10</b> is, at step <b>6716</b>, refused connection to the first protocol service <b>4502</b> and, consequently, connection to the host service <b>4516</b>. In some embodiments, the ticket authority <b>6102</b> receives an initial connection ticket from the intermediary machine <b>30</b> for validation and validates the ticket as described above.

1056Following step <b>6802</b>, the intermediary machine <b>30</b> uses the address of the chosen first protocol service <b>4502</b> to establish, at step <b>6804</b>, a first protocol connection <b>4504</b><i>b </i>between the intermediary machine <b>30</b> and the first protocol service <b>4502</b>. In one embodiment, the intermediary machine <b>30</b> uses an initial connection ticket to establish the first protocol connection <b>4504</b><i>b </i>between the intermediary machine <b>30</b> and the first protocol service <b>4502</b>. In one case, the intermediary machine <b>30</b> uses the same initial connection ticket received from the client machine <b>10</b> to validate the connection <b>4504</b><i>b</i>. In another case, the intermediary machine <b>30</b> uses an initial connection ticket generated for and valid for the first protocol connection <b>4504</b><i>b</i>. A first protocol connection <b>4504</b> therefore now exists, through the intermediary machine <b>30</b>, between the client agent <b>4506</b> of the client machine <b>10</b> and the first protocol service <b>4502</b>. The intermediary machine <b>30</b> can also pass the address of the chosen host service <b>4516</b> to the first protocol service <b>4502</b>.

1057In one embodiment, at step <b>6806</b>, the first protocol service <b>4502</b> uses the address of the chosen host service <b>4516</b> to establish a secondary protocol connection <b>4508</b> between the first protocol service <b>4502</b> and the chosen host service <b>4516</b>. For example, the chosen host service <b>4516</b> is in fact the host service <b>4516</b><i>a </i>and a secondary protocol connection <b>4508</b><i>a </i>is established between the first protocol service <b>4502</b> and the host service <b>4516</b><i>a. </i>

1058In one embodiment, following step <b>6806</b>, the user chooses, at step <b>6808</b>, a second application to be executed and the second remote machine <b>30</b> determines, at step <b>6810</b>, the host service <b>4516</b> on which the second application is to be executed. For example, by calculating a load balancing equation, the second remote machine <b>30</b> may choose the host service <b>4516</b><i>b </i>to execute the second application program. The second remote machine <b>30</b> then transmits the address of the chosen host service <b>4516</b><i>b </i>to the first protocol service <b>4502</b>. In one embodiment, the second remote machine <b>30</b> is in direct communication with the first protocol service <b>4502</b> and directly transmits the address thereto. In another embodiment, the address of the chosen host service <b>4516</b><i>b </i>is indirectly transmitted to the first protocol service <b>4502</b>. For example, the address can be transmitted to the first protocol service <b>4502</b> through any combination of the first remote machine <b>30</b>, the ACR Service <b>5002</b>, the intermediary machine <b>30</b>, and the first protocol service <b>4502</b>. Having received the address of the chosen host service <b>4516</b><i>b</i>, the first protocol service <b>4502</b> establishes, at step <b>6812</b>, a secondary protocol connection <b>4508</b><i>b </i>between the first protocol service <b>4502</b> and the chosen host service <b>4516</b><i>b. </i>

1059The secondary protocols that can be used to communicate over the connections <b>4508</b><i>a </i>and <b>4508</b><i>b </i>include, but are not limited to, HTTP, FTP, Oscar, Telnet, ICA, and RDP. Moreover, in one embodiment, at least one of the secondary protocols, as described above, includes a plurality of virtual channels, each of which can include a plurality of protocol packets enabling functionality at the client machine <b>10</b>. For example, in one embodiment, one host service <b>4516</b><i>a </i>is a web server, communicating with the first protocol service <b>4502</b> over the connection <b>4508</b><i>a </i>using the HTTP protocol, and another host service <b>4516</b><i>b </i>is an application server, communicating with the first protocol service <b>4502</b> over the connection <b>4508</b><i>b </i>using the ICA protocol. The host service <b>4516</b><i>b </i>generates both protocol packets for transmitting graphical screen commands to the client machine <b>10</b>, for causing the client machine <b>10</b> to display a graphical user interface, and protocol packets for transmitting printer commands to the client machine <b>10</b>, for causing a document to be printed at the client machine <b>10</b>.

1060Steps <b>6808</b>, <b>6810</b>, and <b>6812</b> can be repeated any number of times. As such, any number of application programs can be executed on any number of host services <b>4516</b><i>a</i>-<b>4516</b><i>n</i>, the outputs of which can be communicated to the first protocol service <b>4502</b> over the connections <b>4508</b><i>a</i>-<b>4508</b><i>n </i>using any number of secondary protocols.

1061Turning now to step <b>6814</b>, the first protocol service <b>4502</b> can, as described above, encapsulate the plurality of secondary protocols within the first protocol. As such, the client machine <b>10</b> is connected to, and simultaneously communicates with, a plurality of host services <b>4516</b>.

1062In another embodiment, prior to performing steps <b>6808</b>, <b>6810</b>, and <b>6812</b> to execute a new application program on a host service <b>4516</b>, such as, for example, the host service <b>4516</b><i>b</i>, a user of the client machine <b>10</b> ends execution of another application program, such as, for example, an application program executing on host service <b>4516</b><i>a</i>. In such a case, the first protocol service <b>4502</b> disrupts the connection <b>4508</b><i>a </i>between the first protocol service <b>4502</b> and the host service <b>4516</b><i>a</i>. The first protocol service <b>4502</b> then establishes, by implementing steps <b>6808</b>, <b>6810</b>, and <b>6812</b>, the connection <b>4508</b><i>b </i>between the first protocol service <b>4502</b> and the host service <b>4516</b><i>b</i>, without interrupting the connection <b>4504</b> between the client machine <b>10</b> and the first protocol service <b>4502</b>.

1063In one embodiment, a first SID and key is generated at step <b>6816</b>. In some embodiments, a first re-connection ticket is generated. For example, the intermediary machine <b>30</b> requests a first SID and key from the ACR Service <b>5002</b>. Upon receiving the request, the ACR Service <b>5002</b> generates the first SID and key, and can also generate a handle, which is, for example, a random number. The ACR Service <b>5002</b> can then transmit, at step <b>6902</b>, the first SID and key and the handle to the intermediary machine <b>30</b>, while keeping a copy of the first SID and key and a copy of the handle. The ACR Service <b>5002</b> continues to maintain the address of the first protocol service <b>4502</b> that was transmitted to it by the first remote machine <b>30</b> at step <b>6710</b>. The intermediary machine <b>30</b> then transmits, at step <b>6904</b>, the first reconnection ticket to the client machine <b>10</b>.

1064In some embodiments, the intermediary machine <b>30</b> requests a first re-connection ticket from the ticket authority <b>6102</b> or requests a first re-connection ticket for each of the “hops” between the client machine <b>10</b> and the host service <b>4516</b>. Upon receiving the request, the ticket authority <b>6102</b> generates the one or more first re-connection tickets. A re-connection ticket is, for example, a large random number, and can also generate a handle, which is, for example, a smaller random number. The ticket authority <b>6102</b> can then transmit, at step <b>6902</b>, the first re-connection tickets and the handles to the intermediary node <b>632</b>, while keeping a copy of the first re-connection tickets and a copy of the handles. The ticket authority <b>6102</b> continues to maintain the address of the first protocol service <b>4502</b> that was transmitted to it by the first remote machine <b>30</b> at step <b>6710</b>. The intermediary node <b>632</b> then transmits, at step <b>6904</b>, the client's first re-connection ticket to the client machine <b>10</b>.

1065At step <b>6906</b>, a second SID and key is then generated. In one embodiment, the first protocol service <b>4502</b> generates the second SID and key. The first protocol service <b>4502</b>, at step <b>6908</b>, then transmits the second SID and key, through the intermediary machine <b>30</b>, to the client machine <b>10</b>. In doing so, the first protocol service <b>4502</b> keeps a copy of the key and a session number associated therewith for identifying the session to be reconnected following a disruption of the connection <b>4504</b>. In one embodiment, for example, the first protocol service <b>4502</b> maintains, for a particular session number, a table listing the secondary protocol connections <b>4508</b><i>a</i>-<b>4508</b><i>n </i>associated with that session number.

1066At step <b>6906</b>, one or more second re-connection tickets are then generated. In one embodiment, the first protocol service <b>4502</b> generates the second re-connection ticket for the client machine <b>10</b>, which can be, for example, a large random number. In another embodiment, the first protocol service <b>4502</b> generates second re-connection tickets for one or more of the “hops” between the client machine <b>10</b> and the host service <b>4516</b>. The first protocol service <b>4502</b>, at step <b>6908</b>, then transmits the client's second re-connection ticket, through the intermediary machine <b>30</b>, to the client machine <b>10</b>. In doing so, the first protocol service <b>4502</b> keeps a copy of the second re-connection ticket and a session number associated therewith for identifying the session to be re-connected following a disruption of the connection <b>4504</b>. In one embodiment, for example, the first protocol service <b>4502</b> maintains, for a particular session number, a table listing the secondary protocol connections <b>4508</b><i>a</i>-<b>4508</b><i>n </i>associated with that session number. In a like manner, the first protocol service <b>4502</b> may maintain the first and/or second re-connection tickets for each of the “hops” being validated to reconnect the client machine <b>10</b> to the host service <b>4516</b>.

1067Accordingly, following re-establishment of the first protocol connection <b>4504</b> and validation of the second SID and key at the first protocol service <b>4502</b>, or second re-connection ticket, as described below, the first protocol service <b>4502</b> can identify the secondary protocol connections <b>4508</b> to be encapsulated within the re-established first protocol connection <b>4504</b> for communication to the client machine <b>10</b>.

1068In an embodiment not shown in <figref idref="DRAWINGS">FIGS. 67-69</figref>, a ticket authority <b>6102</b> can be used instead of the ACR Service <b>5002</b> to provide for reconnecting a client machine <b>10</b> to a host service <b>4516</b>. In the method <b>6700</b>, the ticket authority <b>6102</b> would generate and transmit reconnection tickets instead of SIDs and keys as with the ACR Service <b>5002</b>. For example, at step <b>6710</b>, a ticket authority <b>6102</b> would provide the client machine <b>10</b> with an initial connection ticket and an address for the intermediary machine <b>30</b>. Also, in step <b>6714</b>, the ticket authority <b>6102</b> would determine if the initial connection ticket is valid and at step <b>6816</b>, would generate a first reconnection ticket. Additionally, at steps <b>6902</b>, <b>6904</b>, <b>6906</b> and <b>6908</b> the ticket authority would generate and transmit the first and second reconnection tickets in accordance with method <b>6700</b>. As such, the ticket authority <b>6102</b> facilitated the reconnecting of the client machine <b>10</b> to the host service <b>4516</b>.

1069Referring now to <figref idref="DRAWINGS">FIG. 70</figref>, one embodiment of a method <b>7000</b> for providing a client machine <b>10</b> with a persistent and reliable connection to one or more host services <b>4516</b> and for reconnecting the client machine <b>10</b> to the host services <b>4516</b> (for example at step <b>6510</b> of <figref idref="DRAWINGS">FIG. 65</figref>) is illustrated. In particular, at step <b>7002</b>, the secondary protocol connection <b>4508</b> between the first protocol service <b>4502</b> and each of the one or more host services <b>4516</b> is maintained. Moreover, at step <b>7004</b>, a queue of data packets most recently transmitted between the client agent <b>4506</b> of the client machine <b>10</b> and the first protocol service <b>4502</b>, via the connection <b>4504</b> that was determined to have broken, for example, at step <b>6510</b> of <figref idref="DRAWINGS">FIG. 65</figref>, is maintained. In one embodiment, the data packets are queued and maintained both before and upon failure of the connection <b>4504</b>. The queued data packets can be maintained, for example, in a buffer by the client agent <b>4506</b>. Alternatively, the first protocol service <b>4502</b> can maintain in a buffer the queued data packets. In yet another embodiment, both the client agent <b>4506</b> and the first protocol service <b>4502</b> maintain the queued data packets in a buffer.

1070At step <b>7006</b>, a new first protocol connection <b>4504</b> is established between the client agent <b>4506</b> of the client machine <b>10</b> and the first protocol service <b>4502</b> and linked to the maintained secondary protocol connection <b>4508</b> between the first protocol service <b>4502</b> and each of the one or more host services <b>4516</b>, thereby reconnecting the client machine <b>10</b> to the host services <b>4516</b>. After the client machine <b>10</b> is reconnected, the queued data packets maintained at step <b>7004</b> can be transmitted, at step <b>7008</b>, via the newly established first protocol connection <b>4504</b>. As such, the communication session between the host services <b>4516</b> and the client machine <b>10</b>, through the first protocol service <b>4502</b>, is persistent and proceeds without any loss of data. In one embodiment, the ACR Service <b>5002</b> authenticates the client machine <b>10</b> to the host service <b>4516</b> before reconnecting the client machine <b>10</b> to a host service <b>4516</b>. In another embodiment, the first protocol service <b>4502</b> validates a reconnection ticket with the ticket authority <b>6102</b> before reconnecting the client machine <b>10</b> to a host service <b>4516</b>.

1071In an embodiment with multiple “hops” traversing multiple first protocol services <b>4502</b>, a portion or all of the data packets may be maintained at one or more of the first protocol services <b>4502</b> so that each “hop” may be re-established. After the client machine <b>10</b> is re-connected and re-linked to the first of the one or more first protocol services <b>4502</b> as described above, each of the remaining connections may be re-established and re-linked to the previously re-linked “hop” until the final “hop” to the host service <b>4516</b> is re-established. Either after the final “hop” is re-established and re-linked, or as each “hop” is re-established and re-linked, the queued data packets maintained can be transmitted.

1072<figref idref="DRAWINGS">FIGS. 71-72</figref>, illustrate one embodiment of a method <b>7100</b> for reconnecting the client machine <b>10</b> to the one or more host services <b>4516</b> using an ACR Service <b>5002</b> as in the embodiment of the system <b>4500</b> depicted in <figref idref="DRAWINGS">FIG. 64</figref>.

1073At step <b>7102</b>, any remaining connections between the client machine <b>10</b> and the first protocol service <b>4502</b> are broken. For example, where the connection <b>4504</b><i>a </i>has failed, but the connection <b>4504</b><i>b </i>has not, the connection <b>4504</b><i>b </i>is broken. Alternatively, where the connection <b>4504</b><i>b </i>has failed, but the connection <b>4504</b><i>a </i>has not, the connection <b>4504</b><i>a </i>is broken.

1074In one embodiment, using the actual address of the intermediary machine <b>30</b> provided to the client machine <b>10</b>, the client agent <b>4506</b> of the client machine <b>10</b> then re-establishes, at step <b>7104</b>, the first protocol connection <b>4504</b><i>a </i>between the client agent <b>4506</b> and the intermediary machine <b>30</b>. Alternatively, in another embodiment, using the actual address of the third remote machine <b>30</b> provided to the client machine <b>10</b>, the client agent <b>4506</b> of the client machine <b>10</b> then reestablishes, at step <b>7104</b>, a first protocol connection between the client agent <b>4506</b> and the third remote machine <b>30</b>. The third remote machine <b>30</b> then determines the intermediary machine <b>30</b> through which messages between the client machine <b>10</b> and the first protocol service <b>4502</b> will have to pass. In one embodiment, the third remote machine <b>30</b> chooses the intermediary machine <b>30</b> using a load balancing equation. The intermediary machine <b>30</b> chosen by the third remote machine <b>30</b> in reconnecting the client machine <b>10</b> to the one or more host services <b>4516</b> can be different from that chosen to initially connect the client machine <b>10</b> to the one or more host services <b>4516</b>. In one embodiment, an initial connection ticket for the chosen intermediary machine <b>30</b> is generated when re-connecting the client machine <b>10</b> to a host service <b>4516</b>.

1075Having chosen the intermediary machine <b>30</b>, the third remote machine <b>30</b> re-establishes a first protocol connection to the intermediary machine <b>30</b>. A first protocol connection <b>4504</b><i>a </i>is therefore re-established, through the third remote machine <b>30</b>, between the client agent <b>4506</b> of the client machine <b>10</b> and the intermediary machine <b>30</b>. In one embodiment, when the first protocol connection <b>4504</b> to the intermediary machine <b>30</b> is re-established, the first protocol connection <b>4504</b> is validated by validating a first or second re-connection ticket for this “hop” with the ticket authority <b>6102</b>.

1076In one embodiment, where more than one level of intermediary machines <b>30</b> exist, the intermediary machine <b>30</b> through which the client agent <b>4506</b> is routed at each of the levels “a”-“n−1” thereafter determines, based on a load balancing equation for example, the intermediary machine <b>30</b> to which it will connect at the next level. Alternatively, in another embodiment, the third remote machine <b>30</b> determines, for more than one or all of the levels “a”-“n”, the intermediary machines <b>30</b> through which the client agent <b>4506</b> will be routed. In other embodiments, either the intermediary machine <b>30</b> or one of the remote machines <b>30</b> (e.g., the third remote machine <b>30</b>) generates first or second re-connection tickets for one or more of the connections or “hops” through which the client agent <b>4506</b> is routed.

1077Having re-established the first protocol connection <b>4504</b><i>a </i>between the client agent <b>4506</b> of the client machine <b>10</b> and the intermediary machine <b>30</b>, for example the intermediate node <b>30</b>′ at level “n” (hereinafter referred to in method <b>7100</b> as the intermediary machine <b>30</b>), the client agent <b>4506</b> then transmits, at step <b>7106</b>, the first SID and key and the second SID and key to the intermediary machine <b>30</b>. In one embodiment, the client agent <b>4506</b> transmits, at step <b>7106</b>, the first re-connection ticket and the second re-connection ticket for the client machine <b>10</b> to the intermediary machine <b>30</b>.

1078It is then determined, at step <b>7108</b>, whether the first SID and key is valid. In one embodiment, the validity of the first SID and key is determined by using the ACR Service <b>5002</b>. For example, the intermediary machine <b>30</b> transmits the first SID and key to the ACR Service <b>5002</b>. In one embodiment, the ACR Service <b>5002</b> determines the validity of the first SID and key by comparing it to a copy of the first SID stored in memory <b>5018</b>. If the ACR Service <b>5002</b> determines the first SID and key to be valid, the ACR Service <b>5002</b> re-authenticates the client machine <b>10</b> to the host service <b>4516</b> and transmits, at step <b>7110</b>, the address of the first protocol service <b>4502</b> to the intermediary machine <b>30</b>. Otherwise, if the ACR Service <b>5002</b> determines the first SID and key to be invalid, the client machine <b>10</b> is, at step <b>7112</b>, refused reconnection to the first protocol service <b>4502</b> and, consequently, reconnection to the host services <b>4516</b>.

1079In one embodiment, the validity of a first re-connection ticket is determined by using the ticket authority <b>6102</b>. For example, the intermediary machine <b>30</b> transmits the first re-connection ticket to the ticket authority <b>6102</b>. In one embodiment, the ticket authority <b>6102</b> determines the validity of the first re-connection ticket by comparing it to a previously kept copy of the first re-connection ticket. If the ticket authority <b>6102</b> determines the first re-connection ticket to be valid, the ticket authority <b>6102</b> transmits, at step <b>7110</b>, the address of the first protocol service <b>4502</b> to the intermediary machine <b>30</b>. Otherwise, if the ticket authority <b>6102</b> determines the first re-connection ticket to be invalid, the client machine <b>10</b> is, at step <b>7112</b>, refused re-connection to the first protocol service <b>4502</b> and, consequently, re-connection to the host services <b>4516</b>.

1080At step <b>7114</b>, the first SID and key is deleted by, for example, the ACR Service <b>5002</b> and a replacement second SID and key is generated by the ACR Service <b>5002</b>. In some such embodiments, the ACR Service <b>5002</b> transmits the second SID and key to the intermediary machine <b>30</b>. In some embodiments, the ACR Service <b>5002</b> waits for the client machine <b>10</b> to acknowledge that it has received the second SID and key before it proceeds to delete the first SID and key.

1081In other embodiments, at step <b>7114</b>, a first re-connection ticket is deleted by, for example, the ticket authority <b>6102</b> and a replacement first re-connection ticket is generated by, for example, the ticket authority <b>6102</b>. Moreover, a replacement handle can be generated by, for example, the ticket authority <b>6102</b>. In some such embodiments, the ticket authority <b>6102</b> transmits the replacement first re-connection ticket and the replacement handle to the intermediary machine <b>30</b>. Moreover, in some such embodiments, the ticket authority <b>6102</b> keeps a copy of the replacement first re-connection ticket. In some embodiments, the ticket authority <b>6102</b> waits for the client machine <b>10</b> to acknowledge that it has received the replacement first re-connection ticket before it proceeds to delete the first re-connection ticket.

1082After the first SID and key (or, in some embodiments, the first re-connection ticket) is validated, the intermediary machine <b>30</b>, using the address of the first protocol service <b>4502</b>, re-establishes, at step <b>7116</b>, the first protocol connection <b>4504</b><i>b </i>between the intermediary machine <b>30</b> and the first protocol service <b>4502</b>. Having re-established the first protocol connection <b>4504</b><i>b </i>between the intermediary machine <b>30</b> and the first protocol service <b>4502</b>, it is then determined whether the second SID and key, or re-connection ticket, is valid.

1083In one embodiment, the validity of the second SID and key is determined by using the first protocol service <b>4502</b>. For example, the intermediary machine <b>30</b> transmits the second SID and key to the first protocol service <b>4502</b>. In one embodiment, the first protocol service <b>4502</b> determines the validity of the second SID and key by comparing it to a previously kept copy of the second SID and encrypted authentication credentials. If the first protocol service <b>4502</b> determines the second SID and key to be valid, the re-established first protocol connection <b>4504</b><i>b </i>between the first intermediary machine <b>30</b> and the first protocol service <b>4502</b> is linked, at step <b>7202</b>, to the maintained secondary protocol connection <b>4508</b> between the first protocol service <b>4502</b> and each of the one or more host services <b>4516</b>. Otherwise, if the first protocol service <b>4502</b> determines the second SID and key to be invalid, the re-established first protocol connection <b>4504</b><i>b </i>is not linked to the one or more maintained secondary protocol connections <b>4508</b> and the client machine <b>10</b> is refused reconnection to the one or more host services <b>4516</b>.

1084In embodiments using re-connection tickets, the validity of the second re-connection ticket is determined by using the first protocol service <b>4502</b>. For example, the intermediary machine <b>30</b> transmits the second re-connection ticket to the first protocol service <b>4502</b>. In one embodiment, the first protocol service <b>4502</b> determines the validity of the second re-connection ticket by comparing it to a previously kept copy of the second re-connection ticket. In another embodiment, the first protocol service <b>112</b> validates a first re-connection ticket for the connection between the first protocol service <b>4502</b> and the host service <b>4516</b>, or in another embodiment, between the first protocol service <b>4502</b> and another first protocol service <b>4502</b> or an intermediary machine <b>30</b>. In a similar manner, each “hop” thereafter between the first protocol service <b>4502</b> and the host service <b>4516</b> may be validated with one or more tickets, either initial or re-connection tickets, to validate the continued use of the “hop” on behalf of the client machine <b>10</b>.

1085If the first protocol service <b>4502</b> determines the second re-connection ticket to be valid, the re-established first protocol connection <b>4504</b><i>b </i>between the first intermediary machine <b>30</b> and the first protocol service <b>4502</b> is linked to the maintained secondary protocol connection <b>4508</b> between the first protocol service <b>4502</b> and each of the one or more host services <b>4516</b>. Otherwise, if the first protocol service <b>4502</b> determines the second re-connection ticket to be invalid, the re-established first protocol connection <b>4504</b><i>b </i>is not linked to the one or more maintained secondary protocol connections <b>4508</b> and the client machine <b>10</b> is refused re-connection to the one or more host services <b>4516</b>. In the case of a multiple-hop connection between the first protocol service <b>4502</b> and the host service <b>4516</b>, each “hop” may be validated for re-connection and be linked to the previous “hop” until the final “hop” to the host service <b>4516</b> is validated, or until one of the “hops” is refused re-connection.

1086At step <b>7204</b>, the second SID and key is deleted by, for example, the first protocol service <b>4502</b> and a replacement second SID and key is generated by, for example, the first protocol service <b>4502</b> for transmission to the client machine <b>10</b>. In such an embodiment, the first protocol service <b>4502</b> keeps a copy of the replacement second SID and key. In some embodiments, the first protocol service <b>4502</b> waits for the client machine <b>10</b> to acknowledge that it has received the replacement second SID and key before it proceeds to delete the second session id and key

1087In some embodiments, the second re-connection ticket is deleted by, for example, the first protocol service <b>4502</b> and a replacement second re-connection ticket is generated by, for example, the first protocol service <b>4502</b> for transmission to the client machine <b>10</b>. In such an embodiment, the first protocol service <b>4502</b> keeps a copy of the replacement second re-connection ticket. In some embodiments, the first protocol service <b>4502</b> waits for the client machine <b>10</b> to acknowledge that it has received the replacement second re-connection ticket before it proceeds to delete the second re-connection ticket. In the case of validating one or more of the “hops” for re-connecting a client <b>108</b>, one or more replacement re-connection tickets, at step <b>948</b>, may be generated and/or a copy saved by the ticket authority <b>136</b>, intermediary nodes <b>632</b>, any of the computing nodes, or one or more of the first protocol services <b>112</b>.

1088At step <b>7206</b>, the replacement second SID and key are transmitted to the client machine <b>10</b>. For example, the ACR Service <b>5002</b> can transmit, through the intermediary machine <b>30</b>, the replacement second SID and key to the client machine <b>10</b>. Moreover, in one embodiment, the first protocol service <b>4502</b> transmits, through the intermediary machine <b>30</b>, the replacement second SID and key to the client machine <b>10</b>.

1089In some embodiments, the replacement first re-connection ticket and the replacement second re-connection ticket are transmitted to the client machine <b>10</b>. For example, the ticket authority <b>6102</b> can transmit, through the intermediary machine <b>30</b>, the replacement first re-connection ticket to the client machine <b>10</b>. Moreover, in one embodiment, the first protocol service <b>4502</b> transmits, through the intermediary machine <b>30</b>, the replacement second re-connection ticket to the client machine <b>10</b>. In other embodiments, the replacement re-connection tickets for one or more “hops” may be transmitted to one or more of the intermediary machine <b>30</b>, any of the computing nodes, or one or more of the first protocol services <b>4502</b>.

1090Alternatively, in other embodiments, the methods described above provide for only a single re-connection ticket for the client machine <b>10</b> and/or a single re-connection for each of the “hops” between the client machine <b>10</b> and a host service <b>4516</b>. As such, rather than using both first and second re-connection tickets, in these embodiments, only the aforementioned single re-connection ticket is used. In one such embodiment, the client agent <b>4506</b> of the client machine <b>10</b> is also provided with the address of the first protocol service <b>4502</b>. To re-connect to the host services <b>4516</b>, the client agent <b>4506</b> transmits the single re-connection ticket directly to the first protocol service <b>4502</b>. The first protocol service <b>4502</b> then determines whether the single re-connection ticket is valid. In one embodiment, the first protocol service <b>4502</b> determines the validity of the single re-connection ticket by comparing it to a previously kept copy of the single re-connection ticket. If the first protocol service <b>4502</b> determines the single re-connection ticket to be valid, the re-established first protocol connection <b>4504</b> between the client machine <b>10</b> and the first protocol service <b>4502</b> is linked to the maintained secondary protocol connection <b>4508</b> between the first protocol service <b>4502</b> and each of the one or more host services <b>4516</b>. Otherwise, if the first protocol service <b>4502</b> determines the single re-connection ticket to be invalid, the re-established first protocol connection <b>4504</b> is not linked to the one or more maintained secondary protocol connections <b>4508</b> and the client machine <b>10</b> is refused re-connection to the one or more host services <b>4516</b>.

1091After the single re-connection ticket is validated, the single re-connection ticket is deleted by, for example, the first protocol service <b>4502</b> and a replacement single re-connection ticket is generated by, for example, the first protocol service <b>4502</b> for transmission to the client machine <b>10</b>. In transmitting the replacement single re-connection ticket to the client machine <b>10</b>, the first protocol service <b>4502</b> keeps a copy of the replacement single re-connection ticket. In some embodiments, the first protocol service <b>4502</b> waits for the client machine <b>10</b> to acknowledge that it has received the replacement single re-connection ticket before it proceeds to delete the single re-connection ticket.

1092In yet another embodiment, like the first and second re-connection tickets, the single re-connection ticket is configured for automatic deletion after a pre-determined period of time following a failure in the connection <b>4504</b>, and/or following a clean termination of the connection <b>4504</b>.

1093In an embodiment not shown in <figref idref="DRAWINGS">FIGS. 71-72</figref>, a ticket authority <b>6102</b> could also be used instead of the ACR Service <b>5002</b> for reconnecting a client machine <b>10</b> to a host service <b>4516</b>. In the method <b>7100</b>, the ticket authority <b>6102</b> would generate and transmit reconnection tickets instead of SIDs and keys as with the ACR Service <b>5002</b>. For example, at step <b>7106</b>, a ticket authority <b>6102</b> would determine in step <b>7108</b> if a first reconnect ticket received from the intermediary machine <b>30</b> in step <b>7106</b> is valid. At step <b>7114</b> the ticket authority <b>6102</b> would delete the first reconnection ticket and generates a second reconnection ticket with a handle. As such, the ticket authority <b>6102</b> facilitates re-establishing and re-authenticating the communication session of the client machine <b>10</b> to the host service <b>4516</b>.

1094Performance of the network <b>150</b> can be monitored to increase performance perceived by the user of a client machine <b>10</b>. The bandwidth and latency of the network <b>150</b> is a factor that affects the interaction experience of the end-user of the client machine <b>10</b>. Other factors include the number of virtual machines executing on a remote machine <b>30</b> or the number of applications executing within a virtual machine on the remote machine <b>30</b>, the amount of data being executed (or load) of the applications, the amount of processing (or load) being done by the client machine <b>10</b>. During operation, each of these factors fluctuates. As data is transmitted through the network <b>150</b> the amount of available bandwidth of the network is reduced. The number of requests to a remote machine <b>30</b> increases and decrease thereby varying the load of the remote machine <b>30</b>. One aspect of the invention features systems and method for determining whether and how these independent changes affect the interaction experience of the end-user.

1095<figref idref="DRAWINGS">FIG. 73</figref> is a conceptual block diagram of an embodiment of a system that includes client software <b>7302</b> and remote machine software <b>7306</b> which monitor the status of the connection between the client machine <b>10</b> and the remote machine <b>30</b>. It should be understood the various modules are not necessarily individual applications. Instead, the modules can be provided as a single software application or grouped as any combination of individual applications. Additionally, certain modules may be physical hardware.

1096The client software <b>7302</b> is in communication with a transceiver module <b>7304</b> of the client machine <b>10</b>. The client software <b>7302</b> includes a trigger module <b>7308</b> in communication with the transceiver module <b>7304</b>. The trigger module <b>7308</b> generates a message <b>7310</b> that is transmitted to the remote machine software <b>7306</b>. The message <b>7310</b> is configured to generate a response from the remote machine software <b>7306</b> when the message is processed by the remote machine <b>30</b>. For example, the message can include a user input event that results in a graphical response from the remote machine. In one embodiment, the trigger module <b>7308</b> generates the message <b>7310</b> on a periodic basis. The length of the period can be configurable by the user of the client machine <b>10</b> or another user such as a system administrator. In another embodiment, the trigger module generates the message <b>7310</b> in response to a specific end-user input using input device <b>7312</b>.

1097The transceiver module <b>7304</b> is in communication with network <b>150</b> and is configured to transmit the message <b>7310</b> from the client machine <b>10</b> to the remote machine <b>30</b> via the network <b>150</b> and receive a response from the remote machine <b>30</b>. If necessary, the transceiver module <b>7304</b> formats the message <b>7310</b> for transmission via the network <b>150</b> and formats the response for execution by the client software <b>7302</b>.

1098Optionally, the client software <b>7302</b> can include a timer module <b>7316</b> and a calculation module <b>7314</b>. The timer module <b>7316</b> is in communication with the trigger module <b>7308</b> and the calculation module <b>7314</b>. The timer module <b>7316</b> is configured to measure the elapsed time from the generation of the message <b>7310</b> until the client machine <b>10</b> completes the instructions included in the response from the remote machine. In one embodiment, the timer module <b>7316</b> generates a start timestamp and a completion timestamp and determines the elapsed time therebetween. In another embodiment, the timer module acts as a stopwatch and generates the elapsed time without performing calculations. In one embodiment, the elapsed time is sent to another remote machine <b>30</b>′ for further processing, such a calculation of an expected elapsed time, trending analysis, and storage. In another embodiment, the elapsed time is forwarded to the calculation module from comparison against an expected value to determine if the environment <b>7300</b> is operating within specification. In still another embodiment, the elapsed time is forwarded to the remote machine <b>30</b> that the client is communicating with.

1099The remote machine software <b>7306</b> is in communication with a transceiver module <b>7326</b> of the remote machine <b>30</b>. The remote machine software <b>7306</b> includes an echo application <b>7318</b>, an optional initiation module <b>7320</b>, and an optional confirmation module <b>7328</b>. In one embodiment, the remote machine software <b>7306</b> is in communication with the application programs <b>7322</b> and the operating system <b>7324</b> that are executing on the remote machine <b>30</b>. In another embodiment, the remote machine software <b>7306</b> is in communication with a computing environment and a hypervisor executing on the remote machine <b>30</b>. In still other embodiments, the remote machine software <b>7306</b> executes in a virtual machine provided by a hypervisor and, in these embodiments, communicates with application programs provided by the computing environment and the virtualized operating system of the virtual machine. The echo application <b>7318</b> is in communication with the transceiver module <b>7326</b> and if present each of the initiation module <b>7320</b> and the confirmation module <b>7328</b>. In one embodiment, the echo application <b>7318</b> is invisible to the end-user of the client machine <b>10</b>. For example, the echo application <b>7318</b> can be a windowless (e.g., stealth application). The end-user does not interact directly with the echo application <b>7318</b>.

1100The echo application generates a graphical response <b>7330</b> to the message <b>7310</b> from the client software <b>7302</b>. The graphical response message <b>7330</b> includes instructions to manipulate, modify, update, alter, or change the display of the client machine <b>10</b> in a manner that is not perceivable by the end-user of the client machine <b>10</b>, but is perceivable by client software <b>7302</b> of the client machine <b>10</b>. In one embodiment, the echo application <b>7318</b> executes invisibly alongside the application programs <b>7322</b>. In such an embodiment, the echo application <b>7318</b> is subject to the same environmental effects and changes as the application programs <b>7322</b>.

1101The transceiver module <b>7326</b> is in communication with network <b>150</b> and is configured to transmit the response <b>7330</b> from the remote machine <b>30</b> to the client machine <b>10</b> via the network <b>150</b> and receive the message <b>7310</b> from the client machine <b>10</b>. If necessary, the transceiver module <b>7304</b> formats the response <b>7330</b> for transmission via the network <b>150</b> and formats the message <b>7310</b> for execution by the remote machine <b>30</b>. The transceiver module forwards the received message <b>7310</b> to the operating system <b>7324</b> of the remote machine <b>30</b>.

1102The operating system <b>7324</b> is configured to read and process the message <b>7310</b> to generate an input event <b>7332</b> for the echo application <b>7318</b>. The input event <b>7332</b> can be a known WINDOWS input event or a custom input event. Conceptually, the input event <b>7332</b> is configured to cause the echo application <b>7318</b> generate the graphic response <b>7330</b>.

1103The initiation module <b>7320</b> is in communication with the application programs <b>7322</b> and the operating system <b>7324</b>. In one embodiment, the initiation module <b>7320</b> monitors the application programs <b>7322</b> and automatically initiates the echo application <b>7318</b> when a specific one of the application of the application programs <b>7322</b> begins executing on the remote machine <b>30</b>. In another embodiment, the initiation module <b>7320</b> initiates the echo application when the remote machine <b>30</b> receives the message <b>7310</b>. In another embodiment, the echo application <b>7318</b> is initiated when a client/remote machine session begins and remains quiescent until the message <b>7310</b> is received. It should be understood that the initiation module can initiate one or more instances of the echo application <b>7318</b>. For example, the initiation module <b>7320</b> may start a respective echo application <b>7318</b> for each client machine <b>10</b> that connects to the remote machine <b>30</b> or that connects to a virtual machine provided by the remote machine <b>30</b>.

1104The confirmation module <b>7328</b> is in communication with the echo application <b>7318</b>. In one embodiment, a function performed by the confirmation module <b>7328</b> includes monitoring the echo application <b>7318</b> to ensure an instance of the echo application <b>7318</b> is executing for each connection between a client machine <b>10</b> and a remote machine <b>30</b> that is of interest. The confirmation module <b>7328</b> may report whether the echo application <b>7318</b> is running and functioning properly to another remote machine <b>30</b>′, such as a management server described above, or the confirmation module <b>7328</b> may report whether the echo application <b>7318</b> is running and functioning properly to the operating system <b>7324</b> of the remote machine <b>30</b> or to a virtual machine provided by a hypervisor.

1105With reference to <figref idref="DRAWINGS">FIG. 74</figref>, an embodiment of a method <b>7400</b> of operation and interaction between the client machine <b>10</b> and remote machine <b>30</b> is described. As a general overview, the method can be conceptualized as a generating a measurement for use in calculating an end-user experience metric in the remote machine based computing environment <b>7300</b>. The operation of the client software <b>7302</b> and the remote machine software <b>7306</b> includes transmitting the message <b>7310</b> to the application <b>7318</b> (step <b>77410</b>), receiving a graphic response (step <b>77420</b>) from the application <b>7318</b>, and determining an elapsed time (step <b>77430</b>) that represents the end-user's interaction experience.

1106In one embodiment, the trigger module <b>7308</b> on the client software <b>7302</b> transmits the message <b>7310</b> via the transceiver <b>7304</b> on a periodic basis. In another embodiment, the trigger module <b>7308</b> generates the message <b>7310</b> in response to end-user input. The message <b>7310</b> can include instructions to generate a WINDOWS message that is forwarded to the application <b>7318</b>. Alternatively, the message <b>7310</b> can be the WINDOWS message and represent an input event to the application <b>7318</b>. In one embodiment, the message <b>7310</b> is transferred over a separate virtual channel within the ICA protocol stream, and a WINDOWS message generated by the remote machine software <b>7306</b> when the message <b>7310</b> is received.

1107When the remote machine software <b>7306</b> receives the message <b>7310</b>, the echo application <b>7318</b> processes the instructions of the message <b>7310</b> and generates the graphic response <b>7330</b>. In one embodiment, the graphic response <b>7330</b> generates a change on the display of the client that is undetectable by the end-user. In various embodiments, the graphic response <b>7330</b> can include instructions to change a small number of pixels on the client display, instructions to change single pixel at the origin (i.e., top left corner) of the client display, instructions to cycle a pixel of the display through a range of values, or instructions to cycle a change through a range of pixel locations of the display.

1108When the client software <b>7302</b> processes the graphic response <b>7330</b>, the elapsed time between the transmission of the transmission of the message <b>7310</b> and the completion of the processing of the graphic response <b>7330</b> is determined. In one embodiment, the client software <b>7302</b> determines the elapsed time and forwards the elapsed time to a management remote machine <b>30</b>′ for storage and trending analysis. In another embodiment, a start timestamp and an end timestamp are forwarded from the timer module <b>7316</b> the management remote machine <b>30</b>′. In such an embodiment the management remote machine <b>30</b>′ determines the elapsed time. It should be understood that the elapsed time measurement is equivalent to the interaction experience as used herein.

1109The management remote machine <b>30</b>′ can store multiple interaction experience measurements. The stored measurements can be used to isolate which portion of a client machine <b>10</b> connection is not performing as expected. For example, network timing measurement for the same time period can be compared to the interaction experience to isolate application, virtual machine, and execution machine load trends. Also, the stored interaction experience measurements can be analyzed using known methods to determine an expected interaction experience value. The expected value can be compared to the measured value, either by the calculation module <b>7314</b> of the client software <b>7302</b> or the management remote machine <b>30</b>′.

1110With reference to <figref idref="DRAWINGS">FIG. 75</figref>, an embodiment of the operational method <b>7500</b> of the remote machine <b>30</b> and remote machine software <b>7306</b> is described. After the client machine <b>10</b> initiates (step <b>77505</b>) established a session with a remote machine <b>30</b>, the remote machine software initiates (step <b>77510</b>) the echo application <b>7318</b>. The remote machine <b>30</b> receives (step <b>77520</b>) the message <b>7310</b> from the client machine <b>10</b>. Once the message <b>7310</b> is received, the confirmation module <b>7328</b> confirms (step <b>77530</b>) that the echo application <b>7318</b> is executing. From the message <b>7310</b>, the operating system <b>7324</b>, or the hypervisor, generates (step <b>77540</b>) the input event <b>7332</b> that is processed by the echo application to generate (step <b>77550</b>) the graphic response <b>7330</b>.

1111The remote machine software <b>7306</b> initiation module <b>7320</b> initiates (step <b>77510</b>) the echo application <b>7318</b> when the client machine <b>10</b> starts the session. In one embodiment, a single echo application <b>7318</b> is initiated. In other embodiments, an echo application <b>7318</b> is started for each of the applications programs <b>7322</b> executing on the remote machine <b>30</b>. In such embodiments, the interaction experience can be measured on an application by application basis. In other embodiments, an echo application <b>7318</b> is started for each of the virtual machines executing on the remote machine <b>30</b>. In these embodiments, the interaction experience can be measured on a virtual machine basis. In another embodiment, a single echo application <b>7318</b> is started for an execution machine executing multiple program application programs <b>7322</b>. For example, a remote machine may communicate with multiple client machines <b>10</b>. Each of the client machines <b>10</b> connects to the remote machine <b>30</b> through a different network path and thus has a different interaction experience. The echo application <b>7318</b> is not visible to the user. That is, the user does not interact directly with the echo application <b>7318</b> and the echo application <b>7318</b> is not show on the display of the client. In one embodiment, the echo application <b>7318</b> is a windowless application.

1112The transceiver module <b>7326</b> receives (step <b>77520</b>) the message <b>7310</b> from the client machine <b>10</b>. In one embodiment, the transceiver module <b>7326</b> includes a network interface card that communicates with the network <b>150</b>. The transceiver module can format the received message <b>7310</b> so that the message <b>7310</b> is readable by the operating system <b>7324</b>.

1113Prior to generating the graphic response <b>7330</b>, the confirmation module <b>7328</b> confirms (step <b>77530</b>) that the echo application <b>7318</b> is executing in user space assigned by the operating system. In some embodiments, the user space is assigned by the native operating system, that is, the operating system of the execution machine. In other embodiments, the user space is assigned by a virtualized operating system, that is, an operating system of a virtual machine provided by a hypervisor. In one embodiment, the confirmation module <b>7328</b> communicates an indication that the echo application <b>7318</b> is executing to the operating system. In one embodiment, the remote machine <b>30</b> creates a log even on the remote machine <b>30</b> to indicate that echo application <b>7318</b> was not running when the message <b>7310</b> was received or when the session was initiated.

1114Once confirmation of the execution of the echo application <b>7318</b> is received, the operating system processes the message <b>7310</b> thereby generating (step <b>77540</b>) the input event <b>7332</b>. In one embodiment, the input event is a WINDOWS message that is forwarded to the echo application <b>7318</b> to model a normal input event WINDOWS message. The input event is designed to cause the echo application <b>7318</b> to generate a graphic response <b>7330</b>. Exemplary input events can include, but are not limited to, mouse movements, keyboard strokes, window generation, window destruction, or any other event that generates a graphic response from the echo application <b>7318</b>. In another embodiment, the input event is a custom “user-defined” application specific WINDOWS message.

1115The echo application <b>7318</b> processes the input event <b>7332</b> and generates (step <b>77550</b>) the graphic response <b>7330</b>, which is in turn forwarded to the client machine <b>10</b>. In various embodiments, the graphic response <b>7330</b> is generated once the echo application <b>7318</b> has performed a set of tasks such as: calculations, memory usage, disk access, and network resource access. The echo application <b>7318</b> can be configured by an administrator to perform specified tasks. In another embodiment, the echo application <b>7318</b> can perform execution tasks that mirror an application program <b>158</b> executing on the remote machine <b>30</b> and generate the graphic response <b>7330</b>. I

1116In one embodiment, the graphic response <b>7330</b> includes instructions that cause a change on the display of the client machine <b>10</b> that is not detectable by the end-user. For example, the graphic response <b>7330</b> includes instructions to change a single pixel at the origin of the display. More complex graphic responses can be used to differentiate from graphic generated by the application programs <b>7322</b> or to detect any response indicators lost from graphic protocol optimizations. For example, the pixel value can cycle through an expected range of values. In another embodiment, the graphic response causes a pixel location to cycle through an expected range of pixel locations. Another example of a graphic response is a BitBit with an unexpected Raster-Operation, either to the display or an off-screen surface (e.g., an off-screen buffer).

1117In addition to measuring the overall end-user interaction experience, in various embodiments, sub-metrics that comprise the overall end-user interaction experience metric can be measured and recorded. Generally, these sub-metrics include the time required by the client machine <b>10</b> to generate and send the trigger message <b>7310</b>, the network <b>150</b> latency, the time required by the remote machine <b>30</b> to process the message <b>7310</b> and generate and transmit the graphic response <b>7330</b>, and the time required by the client machine <b>10</b> to process the graphic response <b>7330</b>.

1118With reference to <figref idref="DRAWINGS">FIG. 76</figref> and <figref idref="DRAWINGS">FIG. 77</figref>, embodiments of a method of generating client machine <b>10</b> sub-metrics are described. From the perspective of the client machine <b>10</b>, there are two types of sub-metrics that are generated a) those related to generating and transmitting the trigger message <b>7310</b> as shown in <figref idref="DRAWINGS">FIG. 76</figref> and b) those related to detecting and processing the graphic response <b>7330</b> as shown in <figref idref="DRAWINGS">FIG. 77</figref>.

1119With reference to <figref idref="DRAWINGS">FIG. 76</figref>, one embodiment of a method <b>7600</b> for capturing sub-metrics related to generating the trigger message <b>7310</b> is described. Assuming that the trigger message <b>7310</b> is generated in response to use of the input device <b>7312</b>, the trigger module <b>7304</b> detects (step <b>77610</b>) use of the input event and marks (step <b>77620</b>) the time of detection. The trigger module generates (step <b>77630</b>) the message <b>7310</b> and marks (step <b>77640</b>) the time the message generating is completed. The trigger module <b>7308</b> forwards the message <b>7310</b> to the transceiver <b>304</b>, which then transmits (step <b>77650</b>) the message <b>7310</b> to the remote machine <b>30</b>. The trigger module <b>7308</b> or the transceiver module <b>7304</b> marks (step <b>77660</b>) the time the message <b>7310</b> is transmitted to the remote machine <b>30</b>.

1120With reference to <figref idref="DRAWINGS">FIG. 77</figref>, one embodiment of a method <b>7700</b> for capturing sub-metrics related to processing the response <b>7330</b> is described. The transceiver <b>304</b> receives (step <b>7710</b>) the graphic response <b>7330</b> from the remote machine <b>30</b> and marks (step <b>7720</b>) the time of receipt. The client software <b>7302</b> process (step <b>7730</b>) the graphic response <b>7330</b>. Upon completion of processing the graphic response <b>7330</b>, the client software <b>7302</b> marks (step <b>7740</b>) the time of completion. Once complete, the client software <b>7302</b> displays the graphic response and detects (step <b>7750</b>) that the graphic response <b>7330</b> is displayed. The client software <b>7302</b> also marks (step <b>7760</b>) the time of detection on the display.

1121The above-described actions of marking certain times that indicate the occurrence of certain events can occur in different ways. In one embodiment, multiple timers are started and stopped by the timer module <b>7316</b> upon the occurrence of each of the above-described events. In another embodiment, a single timer is used and the split times (i.e., the time elapsed between the occurrence of the events) are saved in a table that is accessible by the calculation module <b>7314</b>. In still another embodiment, a time stamp is added to the message <b>7310</b> and the graphic response <b>7330</b> for each of the marking actions. In such an embodiment, prior to transmitting the message <b>7310</b> the time stamps are reported to the calculation module <b>7314</b>, where the elapsed time between each time stamp is determined. These elapsed times represent the above-described different sub-metrics. It should be understood that various combinations of the elapsed times can also be used. For example, the time stamp related to the detection of the use of the input device and the time stamp that indicates the transmission of the message <b>7310</b> can be processed to determine the total elapsed used by the client machine <b>10</b> to generate and send the message <b>7310</b> to the remote machine <b>30</b>. The principles described above with respect to the generation of the message <b>7310</b> are equally applicable to the processing of the graphic response <b>7330</b> by the client machine <b>10</b>.

1122With reference to <figref idref="DRAWINGS">FIG. 78</figref>, one embodiment of a method <b>7800</b> for capturing sub-metrics related to generating the graphic response <b>7330</b> is described. The transceiver <b>320</b> receives (step <b>7810</b>) the message <b>7310</b> from the client machine <b>10</b> and marks (step <b>7820</b>) the time of receipt. The operating system <b>7324</b> then generates (step <b>7830</b>) the input event <b>7332</b>. The remote machine software <b>7306</b> marks (step <b>7840</b>) the time of completion of the generation of the input event <b>7332</b>. The echo application <b>7318</b> receives (step <b>7850</b>) the input event <b>7332</b> and the remote machine software <b>7306</b> marks (step <b>7860</b>) the time of receipt of the input event <b>7332</b>. Once the echo application <b>7318</b> receives the input event, the echo application <b>7318</b> generates (step <b>7870</b>) the graphic response <b>7330</b>. The remote machine software <b>7306</b> marks (step <b>7880</b>) the time the echo application <b>7318</b> completes generating the graphic response <b>7330</b>. In one embodiment, the time required to generate the graphic response <b>7330</b> by the echo application <b>7318</b> includes the echo application performing additional executions tasks that similar to those performed by the application programs <b>7322</b>. The transceiver module <b>7326</b> receives the graphic response <b>7330</b> and transmits (step <b>7890</b>) the graphic response <b>7330</b> to the client machine <b>10</b>. The remote machine software also marks (steps <b>900</b>) the time the graphic response <b>7330</b> is sent.

1123Similar to the marking of events described with reference to the client machine <b>10</b>, the same methods can be employed with regard to the remote machine <b>30</b>. In one embodiment, multiple timers are started and stopped by the timer module <b>7316</b> upon the occurrence of each of the above-described events. In another embodiment, a single timer is used and the split times (i.e., the time elapsed between the occurrence of the events) are saved in a table that is accessible by the calculation module <b>7314</b>. In still another embodiment, a time stamp is added to the graphic response <b>7330</b> for each of the marking actions. In such an embodiment, upon receipt of the graphic response <b>7330</b> the time stamps are reported to the calculation module <b>7314</b>, where the elapsed time between each time stamp is determined. These elapsed times represent the above-described different sub-metrics. It should be understood that various combinations of the elapsed times can also be used. For example, the time stamp related to detecting receipt of the message <b>7310</b> and the time stamp that indicates the transmission of the graphic response <b>7330</b> can be processed to determine the total elapsed used by the remote machine <b>30</b> to generate and send the graphic response to the client machine <b>10</b>.

1124Referring now to <figref idref="DRAWINGS">FIG. 79</figref>, another system for increasing the convenience and usability of the systems described above is shown. A client-server computer system <b>7900</b> includes a first client machine <b>10</b>, a second client machine <b>10</b>, and a remote machine <b>30</b>. The depiction of two client machines is for illustrative purposes only. The client-server computer system can include any number of client machines.

1125In one embodiment, the first client machine <b>10</b> includes an input module <b>7908</b>, a client process <b>7910</b>, a network module <b>7912</b>, and a display module <b>7914</b>. The input module <b>7908</b> provides an interface for a user of the first client machine <b>10</b> to interact with the first client machine <b>10</b>, for example to request the remote execution of an application <b>7916</b> in an application session <b>7918</b> from the remote machine <b>30</b>.

1126An application session <b>7918</b> is a process, operating on the remote machine <b>30</b> that provides access to or supports the execution of one or more resources, such as application <b>7916</b>. An application <b>7916</b> can be a software program, for example, or any organized set of software code capable of being executed by a computer, or hardwired into circuitry in the form of an Application Specific Integrated Circuit (ASIC), read only memory (ROM) microchip, and the like. Example applications include, but are not limited to Microsoft Word (available from Microsoft Corporation Redmond, Wash.), Internet Explorer (Microsoft), Acrobat (available from Adobe Systems, Inc. San Jose, Calif.), etc. In one embodiment, an application session <b>7918</b> includes a desktop application <b>7916</b> from which the execution of other application <b>7916</b> can be initiated. Application sessions <b>7918</b> can be nested within other application sessions <b>7918</b>. In another embodiment, the application session <b>7918</b> includes an instance of the execution of a single application <b>7916</b>.

1127In one embodiment, the input module <b>7908</b> is, for example, a graphical user interface that provides one or more icons or menu selections for a user to select. Each icon or menu selection represents a specific application <b>7916</b> available for remote execution. Selecting an icon or menu selection initiates the transmittal of a log-on request to the remote machine <b>30</b> for access to that application <b>7916</b>. In another embodiment, an icon or menu selection does not represent any specific application <b>7916</b>, but instead represents a general remote machine <b>30</b> log-on procedure. In another embodiment, the input module <b>7908</b> is non-graphical user interface. In this embodiment, the user can enter a command to send a log-on request to remote machine <b>30</b>. Entering a command can include typing a predefined set of characters or depressing a specified key sequence on an input device (e.g., a keyboard or keypad). The log-on request at least includes user-provided authentication information. The input module <b>7908</b> accepts the input of the user-provided authentication information, which can include any type of authentication information, including without limitation any of user name-password/PIN combinations, voice samples, one-time passcodes, biometric data, digital certificates, smart card data, etc. In some embodiments, the input module <b>7908</b> is in communication with additional hardware peripherals (not shown) to facilitate acceptance of user authentication information. In other embodiments, the input module <b>7908</b> can accept authentication information outside of the log-on process.

1128The input module <b>7908</b> accepts authentication information and provides it to the client process <b>7910</b>. The client process <b>7910</b> then manages the client side functionality of the remotely executing application session. The client process <b>7910</b> forwards user input including the authentication information and requests for termination or disconnection of application sessions <b>7918</b> to the remote machine <b>30</b>. The client process <b>7910</b> also handles data incoming from the remote machine <b>30</b>, for example, by forwarding the graphical output of an application session <b>7918</b> to the display module <b>7914</b>.

1129The network module <b>7912</b> provides for communication between the first client machine <b>10</b> and the remote machine <b>30</b>. The network module sends user input, such as authentication information and requests for access to, disconnection from, or termination of application sessions <b>7918</b> executing on the remote machine <b>30</b>. The network module also receives output from the application sessions <b>7918</b> and forwards the output to the client process <b>7910</b>. In one embodiment, the network module <b>7912</b> encapsulates user input into, and reconstitutes application session output from, a predetermined protocol for transmission to the remote machine <b>30</b>. In another embodiment, the network module encrypts outgoing transmissions and decrypts incoming transmissions.

1130The display module <b>7914</b> displays the output of an application <b>7916</b> from a remotely-executing application session <b>7918</b>. The network module <b>7920</b> provides communication functionality for the remote machine <b>30</b>. For example, the network module <b>7920</b> receives communications from first and second client machines <b>10</b> over one or more data networks or links <b>150</b>. The network module <b>7920</b> also transmits resource output data to the first and second client machines <b>10</b>. In one embodiment, the network module <b>7920</b> encrypts outgoing communications and decrypts incoming communications. Likewise, in one embodiment, the network module <b>7920</b> encapsulates outgoing communications in a protocol for transmission and retrieves incoming data from transmissions received according to a protocol. Protocols can include, for example and without limitation, HTTP, Independent Computing Architecture (ICA) protocol (used by Citrix, Systems, Inc. Ft. Lauderdale, Fla.), Remote Desktop Protocol (RDP) (Microsoft Corporation), or Common Gateway Protocol (CGP) (Citrix). The network module <b>7920</b> of the remote machine <b>30</b> communicates with the network module <b>7912</b> of the first client machine <b>10</b> over a network <b>150</b>. The network <b>150</b> can be implemented with any of a variety of suitable technologies. Incoming communications, once decrypted or retrieved from a protocol (if necessary), are forwarded to an application session <b>7918</b> or to the server process <b>7922</b>, as appropriate.

1131The server process <b>7922</b> manages the execution, suspension to disk, resumption of execution, suspension without writing state to disk, and termination of application sessions <b>7918</b> and the connections and disconnections of those application sessions <b>7918</b> to the first and second client machines <b>10</b>. The server process <b>7922</b> can initiate new application sessions <b>7918</b>, disconnect a client machine <b>10</b> from an application session <b>7918</b>, detect a client machine <b>10</b> disconnection from an application session <b>7918</b>, locate an application session <b>7918</b> from which a user has disconnected, locate an application to which a user of the first client machine <b>10</b> is connected to from the second client machine <b>10</b>, and connect a user to a disconnected application session <b>7918</b>. In some embodiments, the application sessions <b>7918</b> are provided so as to be configured with the user's personal preferences and access allowances.

1132The server process <b>7922</b> may execute in the hypervisor, a virtual machine provided by the hypervisor, a guest operating system executing in a virtual machine, an operating system provided by the physical machine or in combinations of those entities.

1133The application output transmitter <b>7924</b> transmits output from an application session <b>7918</b> to a client machine <b>10</b> through the network module <b>7920</b>. The application output transmitter <b>7924</b> intercepts the output of an application session <b>7918</b> and determines which client machine <b>10</b> is connected to the application session <b>7918</b>. In other embodiments, the identity of the client machine <b>10</b> that is connected to the application session <b>7918</b> is stored at the time the connection is made. If the application session <b>7918</b> is connected to a client station, the application output transmitter <b>7924</b> transmits the application output data to the connected client machine <b>10</b> via the network module <b>7920</b>. In one embodiment, if the application session is not connected to a client machine <b>10</b>, the application output transmitter <b>7924</b> discards the application output data and waits to receive future application output data. In another embodiment, if the application session <b>7918</b> is not connected to a client machine <b>10</b>, the application output transmitter <b>7924</b> disregards all further application output data until the application output transmitter <b>7924</b> receives notification that the application session <b>7918</b> has connected to a client machine <b>10</b>. In another embodiment, the application output transmitter <b>7924</b> stores the data until the application output transmitter <b>7924</b> receives notification that the application session <b>7918</b> has connected to a client machine <b>10</b>. In another embodiment, the application output transmitter <b>7924</b> attempts to send application output data to a client machine <b>10</b> until the server process <b>7922</b> notifies the application output transmitter <b>7924</b> that the client machine <b>10</b> is disconnected from the remote machine <b>30</b>. In one embodiment, the application output transmitter <b>7924</b> determines which client machine <b>10</b>, if any, the application session <b>7918</b> is connected to by consulting the data store <b>7926</b>.

1134The data store <b>7926</b> includes information related to application sessions initiated by users. The data store can be stored in volatile or non-volatile memory or, for example, distributed through multiple servers. In some embodiments, the functionality of a data store <b>7926</b> is provided by a session server <b>8620</b> as described in connection with <figref idref="DRAWINGS">FIG. 86</figref>.

1135In one embodiment, remote machine <b>30</b> also includes a rules source <b>7928</b>. The rules source <b>7928</b> stores rules governing the reaction of the server process <b>7922</b> to a user transmitting authentication information to the remote machine <b>30</b>. In one embodiment, the rules stored in the rules source <b>7928</b> are specified at least in part by the system administrator. In another embodiment, a user specifies at least some of the rules stored in the rules source <b>7928</b>. The user-specified rule(s) are stored as preferences. The rules source <b>7928</b> can be stored in volatile or non-volatile memory or, for example, distributed through multiple servers.

1136One rule stored in the rule source <b>7928</b>, for example, might require or forbid automatic connection to disconnected application sessions <b>7918</b>. Another rule might require or forbid automatic connection to active application sessions <b>7918</b> currently connected to a different client machine <b>10</b>. Yet another rule might make connection and/or connection contingent on the client machine <b>10</b> that requests access being within a secure network. A further rule might only allow connection to application sessions <b>7918</b> after receiving user approval. Another rule might only allow connection for a predetermined time after disconnection. Still another rule only allows connection to application sessions <b>7918</b> that include specific application <b>7916</b>.

1137The authentication module <b>7930</b> is responsible for authenticating a user that attempts to log on to the remote machine <b>30</b>. The authentication module <b>7930</b> receives user-provided authentication information transmitted from the first client machine <b>10</b>. The authentication module <b>7930</b> then authenticates the user based on the user-provided authentication information. In response to a successful authentication, the authentication module <b>7930</b> transmits the results of the authentication process (e.g., allow or deny access, the user's system ID, client computer ID, user access permissions, etc.) to the server process <b>7922</b>.

1138In one embodiment, the above-described modules and processes of the remote machine <b>30</b> (i.e., the network module <b>7920</b>, the server process <b>7922</b>, the application output transmitter <b>7924</b>, and the authentication module <b>7930</b>) and a client machine <b>10</b> (i.e. the input module <b>7908</b>, the client process <b>7910</b>, the network module <b>7912</b> and the display module <b>7914</b>) are all implemented in software executable on one of several computer operating systems, including without limitation the Windows family of operating systems (Microsoft Corporation), the MacOS family of operating systems (Apple Computer, Inc., Cupertino, Calif.), and Unix based operating systems (e.g., Solaris, Sun Microsystems, Sunnyvale, Calif.). In other embodiments, one or more modules or processes are implemented in hardware as application specific integrated circuits (ASICs), Read Only Memory (ROM) devices, or other digital hardware circuitry.

1139Unintentional termination of application sessions <b>7918</b> resulting from imperfect network connections and users' failure to terminate their application sessions <b>7918</b> themselves can lead to user difficulties. One embodiment of the invention limits these difficulties by differentiating disconnection (which is treated as if the user is not done working with an application session <b>7918</b>) from termination (which is assumed to be an intentional end to the application session) and by correlating application sessions <b>7918</b> with users as opposed to client machines. When a user is finished using an application <b>7916</b> operating in an application session <b>7918</b>, the user can terminate an application session <b>7918</b>. Termination generally involves the affirmative input of the user indicating that the server should no longer maintain the application session <b>7918</b>. Such affirmative user input can include selecting an “Exit” option from a menu, clicking on an icon, etc. In response to the server process <b>7922</b> receiving a termination request, the execution of the application session <b>7918</b> and any application <b>7916</b> within that application session <b>7918</b> is halted. In one embodiment, data related to the application session <b>7918</b> is also removed from the data store <b>7926</b>.

1140Disconnection, either intentional or unintentional, on the other hand, does not result in termination of application sessions <b>7918</b>. Since the application or applications operating in an application session <b>7918</b> are executing on the remote machine <b>30</b>, a connection to the first client machine <b>10</b> is not usually necessary to continue execution of the application <b>7916</b>, and in one embodiment the application <b>7916</b> can continue to execute while waiting for the user to connect. In an alternative embodiment, upon disconnection of a user, the server process <b>7922</b> stalls the execution of the application <b>7916</b> operating in the application session <b>7918</b>. That is, the server process <b>7922</b> halts further execution of the application <b>7916</b>, and the server process <b>7922</b> stores the operational state of the application <b>7916</b> and any data the application <b>7916</b> is processing. In a further embodiment, the server process <b>7922</b> can selectively stall execution of specific application <b>7916</b> after a user disconnects. For example, in one embodiment, the server continues execution of an application <b>7916</b> for a fixed time period, and if a user fails to connect within that time period, the server process <b>7922</b> stalls the application <b>7916</b>. In another embodiment, the server stalls specified application sessions <b>7918</b> that cannot continue executing without user input. In each of the above-described embodiments, if the user of the first client machine <b>10</b> disconnects from the remote machine <b>30</b> and then connects to the remote machine <b>30</b> while operating the first client machine <b>10</b>, the second client machine <b>10</b>, or a third client computer, the server process <b>7922</b> can connect the client computer operated by the user to one or more previously initiated, non-terminated application session(s) <b>118</b> associated with the user, and reinitiate execution of any stalled application <b>7916</b>.

1141In one embodiment, the server process <b>7922</b> detects a disconnection. A user can intentionally and manually instruct the server to disconnect an application session <b>7918</b> from the client machine <b>10</b> that the user is communicating from. For example, in one embodiment, application sessions <b>7918</b> provide a menu option for disconnection (as distinguished from termination above) that a user can select. The server process <b>7922</b> can also detect an unintentional disconnection. For example, in one embodiment, the network module <b>7920</b> of the remote machine <b>30</b> informs the server process <b>7922</b> when a predetermined number of data packets transmitted by the network module <b>7920</b> to a client machine <b>10</b> have not been acknowledged by the client machine <b>10</b>. In another embodiment, the client machine <b>10</b> periodically transmits a signal to the remote machine <b>30</b> to confirm that a connection is still intact. If the server process <b>7922</b> detects that a predetermined number of expected confirmation signals from a client machine <b>10</b> have not arrived, the server process <b>7922</b> determines that the client machine <b>10</b> has disconnected. If the server process <b>7922</b> detects that a user has disconnected from an application session <b>7918</b>, either intentionally, or unintentionally, the entry in the data store <b>7926</b> related to the disconnected application session <b>7918</b> is modified to reflect the disconnection.

1142Referring also to <figref idref="DRAWINGS">FIG. 80</figref>, a method <b>8000</b> of providing remote access to an application session, in one embodiment, begins with the network module <b>7920</b> of the remote machine <b>30</b> receiving authentication information associated with a user (step <b>8002</b>). Authentication information can include a number of types of authentication information, including without limitation user names, client names, client addresses, passwords, PINs, voice samples, one-time passcodes, biometric data, digital certificates, tickets, etc. and combinations thereof. The authentication information could be in the form of a log-on request from a user. As described above, a log-on request can be initiated by a user through the input module <b>7908</b> of a client machine <b>10</b>. The client's network module forwards the request to the server process <b>7922</b>.

1143In one embodiment, upon receiving the request, the server process <b>7922</b> forwards the user-provided authentication information to the authentication module <b>7930</b>, which authenticates the identity of the user. The server's authentication module <b>7930</b> can perform the authentication itself and/or in cooperation with one or other modules or computers, such as a domain server, an authentication service, etc. Successful authentication results in the authentication module transmitting identification information for the user (e.g., a username or ID) to the server process <b>7922</b>.

1144In response to receiving authentication information associated with the user the server process <b>7922</b> identifies any disconnected application sessions <b>7918</b> associated with the user that are executing, stalled on the remote machine <b>30</b>, or suspended to disk (step <b>8004</b>). In one embodiment, the server process <b>7922</b> identifies the application sessions <b>7918</b> upon receiving the authentication information. In another embodiment, the server process identifies the applications in response to receiving the authentication information after the authentication module <b>7930</b> verifies of the user's identity. In one embodiment, server process <b>7922</b> determines whether any such disconnected application sessions <b>7918</b> exist by consulting the data store <b>7926</b> for sessions, which is some embodiments is a persistent data store, related to the user. For example, the disconnected application session <b>7918</b> could have been disconnected by direction of the user of the application session <b>7918</b>, resulting in the server process <b>7922</b> disconnecting the application session <b>7918</b>, for example, by modifying the status of application session <b>7918</b> in the data store <b>7926</b> to “disconnected,” and deleting the identification of the connected client machine <b>10</b> in the data store <b>7926</b> entry for the application session <b>7918</b>. In another embodiment, the disconnection was unintentional. Unintentional disconnection results in the server process <b>7922</b> making the same modifications to the data store <b>7926</b> as would be made as a result of an intentional disconnection.

1145Upon identifying any disconnected application sessions <b>7918</b> (step <b>8004</b>), in one embodiment, the server process <b>7922</b> prompts the user to indicate whether connection is desired. If connection is not desired, the server process <b>7922</b> prompts the user to indicate whether the disconnected applications sessions <b>7918</b> should remain disconnected, or whether the application sessions <b>7918</b> should be suspended to disk, paused, or terminated. In an alternative embodiment, the server process <b>7922</b> consults a rule stored in the rules source <b>7928</b> to determine whether connection and/or connection is permitted and/or required.

1146In an alternative embodiment, the user connects to the remote machine <b>30</b>, the server process <b>7922</b>, and any disconnected application sessions by utilizing a single user interface element, for example clicking an icon labeled “Log-on.” In this embodiment, activating the single user interface will automatically connect the user to any disconnected applications sessions <b>7918</b>.

1147In one embodiment, the client can be configured to automatically send authentication information upon such user connection. If connection is permitted, and is either assented to by user or is automatic, the server process <b>7922</b> connects the user to the disconnected application sessions (step <b>8006</b>). In one embodiment, connection includes modifying the entry in the data store <b>7926</b> to indicate that the user is connected to the application session <b>7918</b> and to indicate from which client machine <b>10</b> the user is connected to the server. Upon connection, the remote machine <b>30</b> resumes transmitting application output data from the application output transmitter <b>7924</b> to the client <b>10</b> (step <b>8008</b>). In another embodiment, the application output transmitter consults the rules source <b>7928</b> before beginning transmitting application output to ensure such transmission is permitted.

1148Application sessions are associated primarily with users instead of the client machine <b>10</b> which the user was operating when the user previously had connected to, (and then been disconnected from) the server. As a result, rules permitting, the user can reconnect to an application session <b>7918</b> from the first client machine <b>10</b>, the second client machine <b>10</b>, or any other client computer. In other embodiments, the user of the client machine <b>10</b> may be given further options, such as “reconnect to all sessions not executing on a virtual machine,” suspend all sessions executing on a virtual machine,” “reconnect all sessions currently hosted,” or “reconnect to all session not suspended,” for example.

1149Referring to <figref idref="DRAWINGS">FIG. 81</figref>, even if a session is not disconnected (i.e., is active) it can be useful to transfer the session from one client to another. For example, it may be that an application session was disconnected, but the server did not yet detect the disconnection. It may be that the user deliberately left a session running, but would now like to access the session from another location.

1150A method <b>8100</b> for transferring active application sessions <b>7918</b> from a first client machine <b>10</b> to a second client machine <b>10</b> typically begins with the network module <b>7920</b> receiving authentication information from a user, for example in the form of a log-on request. In one embodiment, the user submits the authentication information via the input module <b>7908</b>. The authentication information can be transmitted by the network module <b>7912</b> of second client machine <b>10</b> to the remote machine <b>30</b>. The network module <b>7920</b> of the remote machine <b>30</b> can forward the request to the server process <b>7922</b>.

1151The server process <b>7922</b> receives the user-provided authentication information (step <b>8102</b>). In one embodiment, the server process <b>7922</b> forwards the user-provided authentication information to an authentication module <b>7930</b>, which authenticates the identity of the user using, for example, any of the variety of authentication techniques described above. Successful authentication results in the authentication module transmitting for example, identification information for the user to the server process <b>7922</b>.

1152After receiving authentication information (step <b>8102</b>), the server process consults the data store <b>7926</b> to identify any active application sessions <b>7918</b> that are associated with the user, but that are connected to a different client computer, such as the first client machine <b>10</b> as an illustrative example (step <b>8104</b>). In one embodiment, if the server process <b>7922</b> identifies any such active application sessions <b>7918</b>, the server process automatically disconnects the application session(s) <b>118</b> from the first client machine <b>10</b> (step <b>8106</b>) and connects the application session(s) <b>118</b> to the current client machine <b>10</b> (step <b>8108</b>). In one embodiment, the user can trigger the automatic consultation of the data store and subsequent connection with the selection of a single user interface element.

1153In an alternative embodiment, the server process <b>7922</b> prompts the user as to whether the user wants to have the active application session(s) <b>118</b> connected to the current client machine <b>10</b>. If the user declines to transfer one or more of the active application session(s), the server process <b>7922</b> prompts the user to either keep the application session(s) <b>118</b> active, suspend the application session to disk, pause the application session, or to terminate the application session(s) <b>118</b>. In an alternative embodiment, the server process <b>7922</b> consults a rule stored in the rules source <b>7928</b> to determine whether transfer of the active application session(s) <b>118</b> are permitted before transferring the active application session(s) <b>118</b>.

1154If transfer of the application session(s) <b>118</b> are permitted and transfer is automatic or requested by the user, in one embodiment the server process <b>7922</b> carries out the disconnection (step <b>8106</b>) and connection (step <b>8108</b>) by modifying the entry maintained in the data store <b>7926</b> for the application session <b>7918</b> to substitute the identity of the stored client machine <b>10</b> with the identity of the current client computer, i.e. the client machine <b>10</b>. Upon connection with the current client machine <b>10</b>, the application output transmitter <b>7924</b> begins transmitting application output to the current computer (step <b>8110</b>). In another embodiment, the application output transmitter consults the rules source <b>7928</b> before beginning transmitting application output to ensure such transmission is permitted.

1155It should be understood that the methods of <figref idref="DRAWINGS">FIG. 80</figref> and <figref idref="DRAWINGS">FIG. 81</figref> can be combined to allow a client to be connected to disconnected, suspended, paused, and active sessions associated with a user. In addition, prior to transfer or reconnection, the active and/or disconnected sessions could have been connected to the same or several different client machines.

1156Referring to <figref idref="DRAWINGS">FIG. 82</figref>, as mentioned above, the remote machine <b>30</b> can be implemented as a machine farm <b>38</b>. In one embodiment, the machine farm <b>38</b> includes several remote machines <b>30</b>, <b>30</b>′, and <b>30</b>″, which are linked together and which are jointly administered. Several client machines <b>10</b>, <b>10</b>′, and <b>10</b>″ (typically many computers) can connect to the machine farm <b>38</b> over a network <b>150</b>. The servers <b>30</b>, <b>30</b>′, and <b>30</b>″ share the computational load put on the machine farm <b>38</b>. For example, if a user is accessing three application sessions <b>8218</b><i>a</i>, <b>8218</b><i>b</i>, and <b>8218</b><i>c</i>, each application session can be executing on a different server <b>30</b>, <b>30</b>′, or <b>30</b>″. Similarly, if the user is accessing two or more application <b>7916</b> through a single application session <b>8218</b><i>a</i>, <b>8218</b><i>b </i>or <b>8218</b><i>c</i>, the server process <b>7922</b> of the machine farm <b>38</b> can assign one application to execute on one server <b>30</b> and another application to execute on server <b>30</b>′. In a machine farm configuration, the modules of the server <b>120</b>, <b>122</b>, and <b>124</b>, the data store <b>7926</b>, and the rules source <b>7928</b> (<figref idref="DRAWINGS">FIG. 1</figref>), can be stored on a single server <b>30</b>, <b>30</b>′ or <b>30</b>″, or can be distributed among the servers <b>30</b>, <b>30</b>′, and <b>30</b>″.

1157With respect to connecting to the machine farm <b>38</b> after a disconnection or after changing client machines <b>10</b>, <b>10</b>′ and <b>10</b>″ without disconnecting, the server process <b>7922</b> treats the servers <b>30</b>, <b>30</b>′, and <b>30</b>″ as a single server. That is, if a machine farm is executing a user's application sessions <b>8218</b><i>a</i>, <b>8218</b><i>b</i>, and <b>8218</b><i>c </i>on separate servers <b>30</b>, <b>30</b>′, and <b>30</b>″, and the user disconnects from the machine farm <b>38</b> or changes the client computer <b>10</b>, <b>10</b>′, or <b>10</b>″ at which the user is working, upon subsequently connecting to the machine farm <b>38</b>, the server process <b>7922</b> of the machine farm <b>38</b> can automatically connect the user's client computer <b>10</b>, <b>10</b>′, or <b>10</b>″ with all three application sessions <b>8218</b><i>a</i>, <b>8218</b><i>b</i>, and <b>8218</b><i>c </i>executing on all three severs <b>30</b>, <b>30</b>′, and <b>30</b>″.

1158In one embodiment of the system, a user of a first client computer <b>10</b>, which in this example is a mobile handheld computer, logs on to the machine farm <b>38</b> via a wireless modem and requests two application sessions <b>8218</b><i>a </i>and <b>8218</b><i>b</i>. The server process <b>7922</b> of the machine farm <b>38</b> launches a first application session <b>8218</b><i>a </i>on a first server <b>30</b> and a second application session on a second server <b>30</b>′. The wireless modem loses its connection with the machine farm when the user of the first computer <b>10</b> enters an elevator. The server process <b>7922</b> of the machine farm <b>38</b> determines that the user is disconnected, and the server process <b>7922</b> updates the data store <b>7926</b> accordingly.

1159The user then logs on to the machine farm <b>38</b> from a second client computer <b>10</b>′, which in this example is a desktop computer in his office. The server process <b>7922</b> consults the data store <b>7926</b> and determines that two disconnected application sessions <b>8218</b><i>a </i>and <b>8218</b><i>b </i>are associated with the user. The server process <b>7922</b> (assuming no rules to the contrary) automatically connects the second client computer <b>10</b>′ to both application sessions <b>8218</b><i>a </i>and <b>8218</b><i>b </i>executing on servers <b>30</b> and <b>30</b>′, respectively.

1160The user then leaves the second client computer <b>10</b>′ without disconnecting from the machine farm <b>38</b> and logs on to the machine farm <b>38</b> from a third client computer <b>10</b>″, for example a colleague's laptop. Upon logging on from the third client computer <b>10</b>″, the server process consults the data store <b>7926</b> and determines that the user is associated with the two active application sessions <b>8218</b><i>a </i>and <b>8218</b><i>b </i>connected to the second client computer <b>10</b>′. The server process <b>7922</b> (assuming no rules to the contrary) then automatically disconnects both of the application sessions <b>8218</b><i>a </i>and <b>8218</b><i>b </i>from the second client computer <b>10</b>′, and connects both of the application sessions <b>8218</b><i>a </i>and <b>8218</b><i>b </i>to the third client computer <b>10</b>″.

1161The user next selects a disconnect option for each application session <b>8218</b><i>a </i>and <b>8218</b><i>b</i>. The server process <b>7922</b> updates the data store <b>7926</b> to indicate that the application sessions <b>8218</b><i>a </i>and <b>8218</b><i>b </i>have been disconnected. The user then logs on to the machine farm <b>38</b> from the second client computer <b>10</b>′. The server process <b>7922</b> consults the data store <b>7926</b> and determines that two disconnected application sessions <b>8218</b><i>a </i>and <b>8218</b><i>b </i>are associated with the user. The server process <b>7922</b> (assuming no rules to the contrary) automatically connects the disconnected application sessions <b>8218</b><i>a </i>and <b>8218</b><i>b </i>to the second client computer <b>10</b>′.

1162Referring now to <figref idref="DRAWINGS">FIG. 83</figref>, a flow diagram depicts one embodiment of the steps taken in a method for providing remote access to a computing environment provided by a virtualized operating system. In brief overview, authentication information associated with a user of a client machine <b>10</b> is received (step <b>8302</b>). Based on the received authentication information, a computing environment provided by a virtualized operating system and already associated with the user is identified (step <b>8304</b>). A connection is established between the client machine <b>10</b> and the identified computing environment (step <b>8306</b>).

1163In some embodiments the methods and systems described above in connection with <figref idref="DRAWINGS">FIGS. 79-82</figref> may be implemented in systems including virtual machines. In some embodiments, the client machine <b>10</b> has established a connection to a physical machine providing access to a resource requested by the client machine <b>10</b>. In this embodiment, the client machine <b>10</b> may be connected to a disconnected application session and receive application output as described above in connection with <figref idref="DRAWINGS">FIGS. 79-82</figref>.

1164In other embodiments, the client machine <b>10</b> has established a connection to a virtual machine providing access to a resource. In one of these embodiments, the client machine <b>10</b> may be reconnected to an application session executing on the virtual machine. In another of these embodiments, the client machine <b>10</b> may be reconnected to a plurality of application sessions executing within a computing environment provided by a virtual machine. In still another of these embodiments, the client machine <b>10</b> may be reconnected to an application session comprising a plurality of application programs executing within a computing environment provided by a virtual machine. In yet another of these embodiments, the client machine <b>10</b> may be reconnected to an application session comprising a plurality of computing environments provided by a virtual machine.

1165Referring still to <figref idref="DRAWINGS">FIG. 83</figref>, and in greater detail, authentication information associated with a user of a client machine <b>10</b> is received (step <b>8302</b>). In one embodiment, responsive to the received authentication information, a collection agent gathers information about the client machine <b>10</b>. In some embodiments, the user of the client machine <b>10</b> is authenticated responsive to the received authentication information.

1166Based on the received authentication information, a computing environment provided by a virtualized operating system and already associated with the user is identified (step <b>8304</b>). In some embodiments, the authentication information includes an access control decision, generated as described above in connection with <figref idref="DRAWINGS">FIGS. 7A and 7B</figref>. As described above, a client machine <b>10</b> requests access to a resource, a collection agent gathers information about the client machine <b>10</b>, and a policy engine makes an access control decision. In one of these embodiments, the identification of the computing environment already associated with the user is made in response to the received authentication information. In another of these embodiments, a connection is established between the client machine <b>10</b> and the identified computing environment. In still another of these embodiments, a remote machine <b>30</b>, acting as an intermediary server, receives the authentication information including the access control decision, and establishes a connection between the client machine <b>10</b> and a remote machine <b>30</b>′, acting as an execution machine providing the user of the client machine <b>10</b> with access to the requested resource.

1167In one embodiment, based on the received authentication information and gathered client machine information, a computing environment provided by a virtualized operating system and already associated with the user is identified. In another embodiment, stored data associated with at least one computing environment is consulted to identify, based on the received authentication information, a computing environment provided by a virtualized operating system and already associated with the user. In still another embodiment, based on the received authentication information, an identification is made of a first computing environment provided by a first virtualized operating system and a second computing environment provided by a second virtualized operating system, the first and second computing environments already associated with the user. In yet another embodiment, based on the received authentication information, an identification is made of a first computing environment provided by a first virtualized operating system executing on a first server and a second computing environment provided by a second virtualized operating system executing on a second server, the first and second computing environments already associated with the user

1168A connection is established between the client machine <b>10</b> and the identified computing environment (step <b>8306</b>). In one embodiment, the connection is established between the client machine <b>10</b> and the identified computing environment subject to a rule. In another embodiment, a connection is established between the client machine <b>10</b> and the identified computing environment subject to a policy applied to the received authentication information and gathered client machine information.

1169In some embodiments, a request is received to disconnect the client machine from the identified computing environment. In one of these embodiments, the connection between the client machine and the identified computing environment is terminated. In another of these embodiments, a data record associated with the identified computing environment is updated to indicate that the client machine is disconnected. In still another of these embodiments, an execution of the identified computing environment is continued. The execution may continue although the client is disconnected from the identified computing environment.

1170In some embodiments, authentication information associated with the user is received. In one of these embodiments, the user uses a second client machine <b>10</b>′. In another of these embodiments, an identification is made, based on the received authentication information of a computing environment provided by a virtualized operating system and already associated with the user. In still another of these embodiments, a connection is established between the second client machine <b>10</b>′ and the identified computing environment. In yet another of these embodiments, the connection between the first client machine <b>10</b> and the identified computing environment is terminated.

1171Referring now to <figref idref="DRAWINGS">FIG. 84</figref>, a flow diagram depicts an embodiment of the steps taken in a method for providing remote access to a plurality of application sessions. In brief overview, a selection of a single user interface element by a user of a client machine <b>10</b> is received at the client machine <b>10</b> (step <b>8410</b>). In response to the user interface element selection, authentication information associated with the user is transmitted (step <b>8412</b>). Based on the transmitted authentication information, a computing environment provided by a virtualized operating system and already associated with the user is identified (step <b>8414</b>). A connection is established between the client machine and the identified computing environment (step <b>8416</b>).

1172A selection of a single user interface element by a user of a client machine <b>10</b> is received at the client machine <b>10</b> (step <b>8410</b>). In response to the user interface element selection, authentication information associated with the user is transmitted (step <b>8412</b>). In one embodiment, a collection agent gathers information about the client machine in response to the received information. In another embodiment, a policy engine makes an access control decision responsive to the gathered information, as described above in connection with <figref idref="DRAWINGS">FIG. 7A</figref> and <figref idref="DRAWINGS">FIG. 7B</figref>. In some embodiments, based on the received authentication information and on gathered client machine information, an identification is made of a computing environment provided by a virtualized operating system and already associated with the user. In other embodiments, the user is authenticated responsive to the received authentication information.

1173Based on the transmitted authentication information, a computing environment provided by a virtualized operating system and already associated with the user is identified (step <b>8414</b>). In one embodiment, a connection is established between the client machine and the identified computing environment subject to a rule applied to the received authentication information and to gathered client machine information. In another embodiment, based on the received identification, an identification is made of a first computing environment provided by a first virtualized operating system and a second computing environment provided by a second virtualized operating system, the first and second computing environments already associated with the user. In still another embodiment, based on the received authentication information, an identification is made of a first computing environment provided by a first virtualized operating system executing on a first server and a second computing environment provided by a second virtualized operating system executing on a second server, the first and second computing environments already associated with the user. In some embodiments, stored data associated with at least one computing environment is consulted to identify, based on the received authentication information, a computing environment provided by a virtualized operating system and already associated with the user.

1174A connection is established between the client machine and the identified computing environment (step <b>8416</b>). In one embodiment, the connection between the client machine and the identified computing environment is made subject to a rule. In some embodiments, authentication information associated with the client machine <b>10</b> is received including an access control decision, generated as described above in connection with <figref idref="DRAWINGS">FIGS. 7A and 7B</figref>. In one of these embodiments, the identification of the computing environment already associated with the user is made in response to the received authentication information. In another of these embodiments, a remote machine <b>30</b>, acting as an intermediary broker server, receives the authentication information including the access control decision, and establishes a connection between the client machine <b>10</b> and a remote machine <b>30</b>′, acting as an execution machine providing the user of the client machine <b>10</b> with access to the requested resource.

1175In some embodiments, a request is received to disconnect the client machine from the identified computing environment. In one of these embodiments, the connection between the client machine and the identified computing environment is terminated. In another of these embodiments, a data record associated with the identified computing environment is updated to indicate that the client machine is disconnected. In still another of these embodiments, execution of the identified computing environment is continued. The execution may continue although the user has terminated the connection between the client machine and the identified computing environment.

1176In some embodiments, authentication information associated with the user is received, the user using a second client machine <b>10</b>′. In one of these embodiments, based on the received authentication information, an identification is made of a computing environment provided by a virtualized operating system and already associated with the user. In another of these embodiments, a connection is established between the second client machine <b>10</b>′ and the identified computing environment. In yet another of these embodiments, a connection between the first client machine <b>10</b> and the identified computing environment is terminated.

1177Referring now to <figref idref="DRAWINGS">FIG. 85</figref>, a block diagram depicts one embodiment of a server for providing remote access to a computing environment. In brief overview, a remote machine <b>30</b> is a server and includes a network module <b>7920</b>, a data store <b>7926</b>, and a broker process <b>8532</b>. In some embodiments, the remote machine <b>30</b> the components, modules and subsystems described above in connection with <figref idref="DRAWINGS">FIG. 79</figref>.

1178The network module <b>7920</b> receives authentication information associated with a user operating a client machine, such as client machine <b>10</b>. In some embodiments, the network module <b>7920</b> is in communication with an authentication module for authenticating the user in response to the received authentication information. In other embodiments, the network module <b>7920</b> includes the authentication module.

1179The data store <b>7926</b> contains an identifier of a computing environment associated with the user. In one embodiment, the data store <b>7926</b> contains a first identifier of a first computing environment associated with the user and a second identifier of a second computing environment associated with the user. In another embodiment the first computing environment executes on a first remote machine <b>30</b> and the second computing environment executes on a second remote machine <b>30</b>′. In some of these embodiments, the broker process <b>8532</b> transmits the enumeration from the data store to the client machine <b>10</b>.

1180The broker process <b>8532</b> connects the client machine <b>10</b> to the identified computing environment enumerated in the data store <b>7926</b>, in response to the received information. In one embodiment, the broker process <b>8532</b> connects the client machine <b>10</b> to the identified computing environment subject to a rule. In another embodiment, the broker process <b>8532</b> disconnects the client machine <b>10</b> from the identified computing environment in response to a received disconnect signal. In still another embodiment, the broker process <b>8532</b> updates a data record associated with the identified computing environment to indicate the client machine <b>10</b> is disconnected from the identified computing environment.

1181In some embodiments, the remote machine <b>30</b> includes a collection agent and a policy engine. In one of these embodiments, the collection agent gathers information about the client machine <b>10</b>. In another of these embodiments, the collection agent comprises at least one script. In still another of these embodiments, the collection agent comprises bytecode. In yet another of these embodiments, the collection agent gathers the information by running at least one script on the client machine <b>10</b>. In some of these embodiments, the collection agent executes on the client machine <b>10</b>. In others of these embodiments, the collection agent is transmitted to the client machine <b>10</b>. In one of these embodiments, the policy engine transmits the collection agent to the client machine <b>10</b>.

1182In some of these embodiments, the remote machine <b>30</b> includes a policy engine receiving the gathered information and assigning one of a plurality of levels of access responsive to application of a policy to the received information, the broker process <b>8532</b> connecting the client machine to the identified computing environment enumerated in the data store responsive to the assigned access level. In one embodiment, the policy engine further comprises a database storing configurable policies. In another embodiment, the policy engine transmits instructions to the collection agent determining the type of information the collection agent gathers.

1183In others of these embodiments, the policy engine further comprises a logon agent. In one of these embodiments, the logon agent receives the gathered information from the collection agent. In another of these embodiments, the logon agent identifies for the policy engine authentication information received from the collection agent. In still another of these embodiments, the policy engine further comprises a plurality of logon agents. In yet another of these embodiments, at least one of the plurality of logon agents resides on each network domain from which a client machine <b>10</b> may transmit a resource request. In some embodiments, the client machine <b>10</b> transmits the resource request to a particular logon agent. In other embodiments, the logon agent identifies for the policy engine the network domain from which the client machine transmits the resource request.

1184In some embodiments, a virtual machine farm provides functionality for relocating a session from one requesting machine to a second requesting machine. In one of these embodiments, the virtual machine farm provides access to information required for relocating a session. In another of these embodiments, a hypervisor provides functionality for relocating a virtual machine session. In some embodiments, the hypervisor implements well-known techniques, including pre-copying, post-copying, and lazy-copying for moving session information associated with a virtual machine session from one execution machine to a second execution machine.

1185In some embodiments, the virtual machine farm is in communication with a system as described in <figref idref="DRAWINGS">FIG. 86</figref> and <figref idref="DRAWINGS">FIG. 87</figref>, and provides functionality for relocation of an application session within a virtual machine session.

1186Referring to <figref idref="DRAWINGS">FIG. 86</figref>, one embodiment of a network constructed in accordance with the invention is depicted, which includes a client machine <b>10</b>, a collection agent <b>704</b>, a policy engine <b>706</b>, a policy database <b>708</b>, a condition database <b>710</b>, a client machine <b>10</b>′, a session server <b>8620</b>, a stored application database <b>8622</b>, a remote machine <b>30</b>′, a first database <b>8628</b>, a remote machine <b>30</b>″, and a second database <b>8632</b>. In brief overview, when the client machine <b>10</b> transmits to the policy engine <b>706</b> a request <b>206</b> for access to an application program, the collection agent <b>704</b> communicates with client machine <b>10</b>, retrieves information about client machine <b>10</b>, and transmits client machine information <b>714</b> to the policy engine <b>706</b>. The policy engine <b>706</b> makes an access control decision, as discussed above in <figref idref="DRAWINGS">FIG. 7A</figref> and <figref idref="DRAWINGS">FIG. 7B</figref>. The client machine <b>10</b> receives an enumeration of available applications associated with the client machine <b>10</b>.

1187In some embodiments, the session server <b>8620</b> establishes a connection between the client machine <b>10</b> and a plurality of application sessions associated with the client machine <b>10</b>. In one of these embodiments, the connection is established to a virtual machine providing access to a computing environment in which the application sessions execute. In other embodiments, the policy engine <b>706</b> determines that the client machine <b>10</b> has authorization to retrieve a plurality of application files comprising the application and to execute the application program locally. In one of these embodiments, the remote machine <b>30</b>′ stores application session data and a plurality of application files comprising the application program. In another of these embodiments, the client machine <b>10</b> establishes an application streaming session with a remote machine <b>30</b>′ storing the application session data and the plurality of application files comprising the application program.

1188Referring now to <figref idref="DRAWINGS">FIG. 87</figref>, a flow diagram depicts one embodiment of the steps taken by the session server <b>8620</b> to provide access for the client machine <b>10</b> to its associated application sessions. The session server <b>8620</b> receives information about the client machine <b>10</b> from the policy engine <b>706</b> containing the access control decision the policy engine <b>706</b> made (step <b>8780</b>). In one embodiment, the information also includes the client machine information <b>714</b>. In another embodiment, the information includes authorization to execute the application program locally. In still another embodiment, the information includes authorization to provide access to computing environment in which the application program executes.

1189In some embodiments, the policy engine <b>706</b> identifies a plurality of application sessions already associated with the client machine <b>10</b>. In other embodiments, the session server <b>8620</b> identifies stored application sessions associated with the client machine <b>10</b> (step <b>8782</b>). In some of these embodiments, the session server <b>8620</b> automatically identifies the stored application sessions upon receiving the information from the policy engine <b>706</b>. In one embodiment, the stored application database <b>8622</b> resides on the session server <b>8620</b>. In another embodiment, the stored application database <b>8622</b> resides on the policy engine <b>706</b>.

1190The stored application database <b>8622</b> contains data associated with a plurality of machines <b>30</b> in the machine farm <b>38</b> executing application sessions or providing access to application session data and application files comprising application programs, or providing access to computing environments in which application sessions may execute, including virtual machines which may be active, suspended, paused or disconnected. In some embodiments, identifying the application sessions associated with the client machine <b>10</b> requires consulting stored data associated with one or more machines <b>30</b>. In some of these embodiments, the session server <b>8620</b> consults the stored data associated with one or more machines <b>30</b>. In others of these embodiments, the policy engine <b>706</b> consults the stored data associated with one or more machines <b>30</b>. In some embodiments, a first application session runs on a remote machine <b>30</b>′ and a second application session runs on a remote machine <b>30</b>″. In other embodiments, all application sessions run on a single remote machine <b>30</b> within the machine farm <b>38</b>. In still other embodiments one or more application sessions run on a remote machine <b>30</b> executing a virtual machine providing access to a computing environment in which the application sessions execute.

1191The session server <b>8620</b> includes information related to application sessions initiated by users. The session server can be stored in volatile or non-volatile memory or, for example, distributed through multiple servers. Table 4 shows the data included in a portion of an illustrative session server <b>8620</b>:

0000<tables id="TABLE-US-00009" num="00009"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="offset" colwidth="56pt" align="left" /><colspec colname="1" colwidth="161pt" align="center" /><thead><row><entry /><entry namest="offset" nameend="1" rowsep="1">TABLE 4</entry></row></thead><tbody valign="top"><row><entry /><entry namest="offset" nameend="1" align="center" rowsep="1" /></row><row><entry /><entry>Application Session</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="offset" colwidth="56pt" align="left" /><colspec colname="1" colwidth="63pt" align="left" /><colspec colname="2" colwidth="49pt" align="left" /><colspec colname="3" colwidth="49pt" align="left" /><tbody valign="top"><row><entry /><entry>App Session 1</entry><entry>App Session 2</entry><entry>App Session 3</entry></row><row><entry /><entry namest="offset" nameend="3" align="center" rowsep="1" /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="56pt" align="left" /><colspec colname="2" colwidth="63pt" align="left" /><colspec colname="3" colwidth="49pt" align="left" /><colspec colname="4" colwidth="49pt" align="left" /><tbody valign="top"><row><entry>User ID</entry><entry>User 1</entry><entry>User 2</entry><entry>User 1</entry></row><row><entry>Client ID</entry><entry>First Client</entry><entry /><entry>First Client</entry></row><row><entry>Client Address</entry><entry>172.16.0.50</entry><entry /><entry>172.16.0.50</entry></row><row><entry>Status</entry><entry>Active</entry><entry>Disconnected</entry><entry>Active</entry></row><row><entry>Applications</entry><entry>Word Processor</entry><entry>Data Base</entry><entry>Spreadsheet</entry></row><row><entry>Process Number</entry><entry>1</entry><entry>3</entry><entry>2</entry></row><row><entry>Server</entry><entry>Server A</entry><entry>Server A</entry><entry>Server B</entry></row><row><entry>Server Address</entry><entry>172.16.2.55</entry><entry>172.16.2.55</entry><entry>172.16.2.56</entry></row><row><entry>Executing in a</entry><entry>Yes (Instance ID #)</entry><entry>No</entry><entry>no</entry></row><row><entry>Virtual Machine?</entry></row><row><entry namest="1" nameend="4" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

1192The session server <b>8620</b> in Table 4 includes data associating each application session with the user that initiated the application session, an identification of the client machine <b>10</b>, if any, from which the user is currently connected to the remote machine <b>30</b>′, and the IP address of that client computer <b>10</b>. The session server <b>8620</b> also includes the status of each application session. The data may include an identification of a virtual machine providing a computing environment in which the application session executes. An application session status can be, for example, “active” (meaning a user is connected to the application session), or “disconnected” (meaning a user is not connected to the application session). In an alternative embodiment, an application session status can also be set to “executing-disconnected” (meaning the user has disconnected from the application session, but the applications in the application session are still executing), or “stalled-disconnected” (meaning the user is disconnected and the applications in the application session are not executing, but their operational state immediately prior to the disconnection has been stored). The session server <b>8620</b> further stores information indicating the application <b>7916</b> that are executing within each application session and data indicating each application's process on the server. For embodiments in which the session is hypervisor-based, the session server <b>8620</b> may store an identification of a hypervisor domain or a virtual machine instance identifier. In embodiments in which the remote machine <b>30</b>′ is part of the machine farm <b>38</b>, the session server <b>8620</b> is at least a part of the dynamic store in addition to the data in the last three rows of Table 4 that identify a remote machine <b>30</b> in the machine farm <b>38</b> on which each application is/was executing, and the IP address of that remote machine <b>30</b>. In alternative embodiments, the session server <b>8620</b> includes a status indicator for each application in each application session.

1193For example, in the example of Table 4, three application sessions exist, App Session 1, App Session 2, and App Session 3. App Session 1 is associated with User 1, who is currently using terminal <b>1</b>. Terminal one's IP address is 172.16.2.50. The status of App Session 1 is active, and in App Session 1, a word processing program, is being executed. The word processing program is executing on Server A as process number 1. Server A's IP address is 172.16.2.55. App Session 2 in Table 1 is an example of a disconnected application session <b>7918</b>. App Session 2 is associated with User 2, but App Session 2 is not connected to a client machine <b>10</b> or <b>20</b>. App Session 2 includes a database program that is executing on Server A, at IP address 152.16.2.55 as process number 3. App Session 3 is an example of how a user can interact with application sessions operating on different remote machines <b>30</b>. App Session 3 is associated with User 1, as is App Session 1. App Session 3 includes a spreadsheet program that is executing on Server B at IP address 152.16.2.56 as process number 2, whereas the application session included in App Session 1 is executing on Server A. Although only one App Session 1 is described in the application session, the application session may comprise a plurality of executing resources, including application sessions executing in computing environments and computing environments executing in a virtual machine.

1194In another example, a user may access a first application program through an application session executing on a remote machine <b>30</b>′, such as Server A, while communicating across an application streaming session with a second remote machine <b>30</b>″, such as Server B, to retrieve a second application program from the second remote machine <b>30</b>″ for local execution. The user of the client machine <b>10</b> may have acquired authorization to execute the second application program locally while failing to satisfy the local execution pre-requisites of the first application program.

1195In one embodiment, the session server <b>8620</b> is configured to receive a disconnect request to disconnect the application sessions associated with the client machine <b>10</b> and disconnects the application sessions in response to the request. The session server <b>8620</b> continues to execute an application session after disconnecting the client machine <b>10</b> from the application session. In this embodiment, the session server <b>8620</b> accesses the stored application database <b>8622</b> and updates a data record associated with each disconnected application session so that the record indicates that the application session associated with the client machine <b>10</b> is disconnected.

1196After receiving authentication information associated with a client machine <b>10</b> connecting to the network, the session server <b>8620</b> consults the stored applications database <b>8622</b> to identify any active application sessions that are associated with a user of the client machine <b>10</b>, but that are connected to a different client machine <b>10</b>, such as the client machine <b>10</b> if the authentication information is associated with client machine <b>10</b>′, for example. In one embodiment, if the session server <b>8620</b> identifies any such active application sessions, the session server <b>8620</b> automatically disconnects the application session(s) from the client machine <b>10</b> and connects the application session(s) to the current client machine <b>10</b>′ (step <b>8784</b>). In some embodiments, the received authentication information will restrict the application sessions to which the client machine <b>10</b> may reconnect. In other embodiments, the received authentication information authorizes execution of an application program on the client machine <b>10</b>′, where the authorization may have been denied to client machine <b>10</b>. In one of these embodiments, the session server <b>8620</b> may provide the client machine <b>10</b> access information for retrieving the application program for second execution. In still other embodiments, the received authentication information authorizes execution of an application program in a computing environment provided by a virtual machine.

1197Referring now to <figref idref="DRAWINGS">FIG. 88</figref>, a block diagram depicts one particular embodiment of a system for providing, by a virtual machine access to a computing environment. A client agent <b>8802</b> on a client machine <b>10</b> connects to a remote machine <b>30</b>. In some embodiments, the client agent <b>8802</b> establishes a connection with a session management component <b>1300</b>. In other embodiments, the session management component <b>1300</b> is executed by the remote machine <b>30</b> to which the client machine <b>10</b> connects. In one embodiment, the session management component <b>1300</b> queries a virtual machine management component <b>1200</b>, for the location of the configuration and virtual disk files of a virtual machine to run for the current user and a hypervisor in which the virtual machine may execute. In some embodiments, the identified hypervisor and virtual machine execute on remote machine <b>30</b>. In other embodiments, the identified hypervisor and virtual machine execute on a remote machine <b>30</b>′. In one embodiment, the session management component launches the virtual machine within the specified hypervisor in full screen mode. In another embodiment, a previously-executing virtual machine is allocated to the client machine <b>10</b>.

1198In some embodiments, a virtual machine service component <b>8804</b> executes within a computing environment provided by a virtual machine on a remote machine <b>30</b>. In one of these embodiments, the virtual machine service component <b>8804</b> receives an IP address and a port with which to establish a communication channel between the session management component <b>1300</b> and the virtual machine service component <b>8804</b>. In one embodiment, this communication channel is used to pass session related configuration information from the client agent session into the virtual machine session. In some embodiments, the configuration information includes display settings and changes, client drive information and authentication data with which to enable single sign-on for a user of the client machine <b>10</b>.

1199In some embodiments, once the communications channel is established and the initial session related information is passed to the virtual machine service component <b>8804</b>, the virtual machine service component <b>8804</b> automatically connects the user to a computing environment, such as a guest operating system, using the same credentials as were provided to the client agent <b>8802</b> by the user (if any). In one of these embodiments, the virtual machine service component <b>8804</b> automatically reconfigures the display settings of the guest operating system to match those of the client <b>8802</b>. The virtual machine produces graphics and sound output to virtual devices that redirect that output, directly or indirectly, to the client agent <b>8802</b> on the client machine <b>10</b>. The virtual machine receives audio input, mouse and keyboard device data redirected from the client machine <b>10</b>. When the virtual machine is shutdown or suspended the session management component <b>1300</b> terminates the client agent session.

1200Referring now to <figref idref="DRAWINGS">FIG. 95</figref>, a block diagram depicts one embodiment of a system for providing to a first client agent, via a second client agent on a first remote machine, output data generated by a resource executing in a virtual machine provided by a second remote machine. A client agent <b>8802</b> on a client machine <b>10</b> connects to a remote machine <b>30</b> and requests access to a resource. In one embodiment, the remote machine <b>30</b> is an intermediate machine. In another embodiment, the remote machine <b>30</b> determines to provide access to the requested resource via a virtual machine. In still another embodiment, the remote machine <b>30</b> identifies a remote machine <b>30</b>′ to provide access to the requested resource via a virtual machine executing on the remote machine <b>30</b>′. The remote machine <b>30</b>′ may be referred to as an execution machine <b>30</b>′.

1201In one embodiment, the client machine <b>10</b> communicates with the remote machine <b>30</b> using a presentation layer protocol, such as ICA, RDP, VNC, or X11. In some embodiments, protocol stacks are implemented to enable communications between the client machine <b>10</b> and remote machines <b>30</b>, as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>, step <b>816</b> and with <figref idref="DRAWINGS">FIG. 24</figref>.

1202In one embodiment, an agent <b>8802</b>′ on the remote machine <b>30</b> establishes a connection to the remote machine <b>30</b>′. In another embodiment, the remote machine <b>30</b> communicates with the remote machine <b>30</b>′ using a presentation layer protocol, such as ICA, RDP, VNC, or X11. In still another embodiment, the remote machine <b>30</b> establishes a connection with the remote machine <b>30</b>′ and communicates with the remote machine <b>30</b>′ using a presentation layer protocol, such as RDP, from within a terminal services session executing on the remote machine <b>30</b>. In some embodiments, protocol stacks are implemented to enable communications between the agent <b>8802</b>′ on the remote machine <b>30</b> and the remote machine <b>30</b>′, as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>, step <b>816</b> and with <figref idref="DRAWINGS">FIG. 24</figref>.

1203In one embodiment, as depicted by <figref idref="DRAWINGS">FIG. 95</figref>, the remote machine <b>30</b>′ provides access to the requested resource by providing access to a virtualized environment or by providing access to an application streaming service, as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>. In another embodiment, the remote machine <b>30</b>′ executes the resource in a virtual machine executing on the remote machine <b>30</b>′. In still another embodiment, the remote machine <b>30</b>′ transmits output data generated by the execution of the resource to the remote machine <b>30</b> using a presentation layer protocol. In another embodiment, the remote machine <b>30</b> forwards the output data received from the remote machine <b>30</b>′ to the client machine <b>10</b> using a presentation layer protocol. In some embodiments, the virtual machine executes on the remote machine <b>30</b>′. In other embodiments, the virtual machines execute on a remote machine <b>30</b>″.

1204In one embodiment, the remote machine <b>30</b>′ provides access to a published desktop computing environment. In another embodiment, the remote machine <b>30</b>′ provides access to a published desktop computing environment selected from an enumeration of a plurality of published desktop computing environments available to the client machine <b>10</b>. In some embodiments, as described above in connection with the description of the virtual machine management component <b>1200</b>, virtual machines may provide access to standard operating environments.

1205Referring now to <figref idref="DRAWINGS">FIG. 96</figref>, a block diagram depicts an embodiment of a system for providing to a first client agent, via a second client agent on a first remote machine, output data generated by a resource executing in a virtual machine provided by a second remote machine. A client agent <b>8802</b> on a client machine <b>10</b> connects to a remote machine <b>30</b> and requests access to a resource. In one embodiment, the remote machine <b>30</b> is an intermediate machine. In another embodiment, the remote machine <b>30</b> determines to provide access to the requested resource via a virtual machine. In still another embodiment, the remote machine <b>30</b> identifies a remote machine <b>30</b>′ to provide access to the requested resource via a virtual machine executing on the remote machine <b>30</b>′. The remote machine <b>30</b>′ may be referred to as an execution machine <b>30</b>′.

1206In one embodiment, the client machine <b>10</b> communicates with the remote machine <b>30</b> using a presentation layer protocol, such as ICA, RDP, VNC, or X11. In some embodiments, protocol stacks are implemented to enable communications between the client machine <b>10</b> and remote machines <b>30</b>, as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>, step <b>816</b> and with <figref idref="DRAWINGS">FIG. 24</figref>.

1207In one embodiment, an agent <b>8802</b>′ on the remote machine <b>30</b> establishes a connection to the remote machine <b>30</b>′. In another embodiment, the remote machine <b>30</b> communicates with the remote machine <b>30</b>′ using a presentation layer protocol, such as ICA, RDP, VNC, or X11. In still another embodiment, the remote machine <b>30</b> establishes a connection with the remote machine <b>30</b>′ and communicates with the remote machine <b>30</b>′ using a presentation layer protocol, such as ICA. In some embodiments, protocol stacks are implemented to enable communications between the agent <b>8802</b>′ on the remote machine <b>30</b> and the remote machine <b>30</b>′, as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>, step <b>816</b> and with <figref idref="DRAWINGS">FIG. 24</figref>.

1208In one embodiment, as depicted by <figref idref="DRAWINGS">FIG. 96</figref>, the remote machine <b>30</b>′ provides access to the requested resource by providing access to a virtualized environment or by providing access to an application streaming service, as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>. In another embodiment, the remote machine <b>30</b>′ executes the resource in a virtual machine executing on the remote machine <b>30</b>′. In still another embodiment, the remote machine <b>30</b>′ transmits output data generated by the execution of the resource to the remote machine <b>30</b> using a presentation layer protocol. In another embodiment, the remote machine <b>30</b> forwards the output data received from the remote machine <b>30</b>′ to the client machine <b>10</b> using a presentation layer protocol. In some embodiments, the virtual machine executes on the remote machine <b>30</b>′. In other embodiments, the virtual machines execute on a remote machine <b>30</b>″.

1209Referring now to <figref idref="DRAWINGS">FIG. 97</figref>, a block diagram depicts one embodiment of a system for identifying, by a coordinator machine, a worker machine providing, via a virtual machine, access to a computing environment. A client agent <b>8802</b> on a client machine <b>10</b> connects to a remote machine <b>30</b> and requests access to a resource. In one embodiment, the remote machine <b>30</b> is a coordinator machine, providing the functionality of an intermediate broker machine. In another embodiment, the remote machine <b>30</b> identifies a remote machine <b>30</b>′ to provide access to the requested resource.

1210In some embodiments, the remote machine <b>30</b> is a remote machine in a plurality of remote machines functioning as intermediate broker machines. In one of these embodiments, the coordinator machines receive requests and identify other remote machines <b>30</b>′ from a second plurality of remote machines, the identified machines responding to the requests. In another of these embodiments, the identified remote machines <b>30</b>′ are referred to as worker machines. In still another of these embodiments, the client machine <b>10</b> communicates with the coordinator machine <b>30</b> using a presentation layer protocol, such as ICA, RDP, VNC, or X11.

1211In one embodiment, the coordinator machine <b>30</b> identifies a pool of worker machines <b>30</b>′ each capable of providing access to the requested resource. In some embodiments, the coordinator machine <b>30</b> identifies a worker machine <b>30</b>′ from the pool of worker machines <b>30</b>′ capable of providing access to the requested resource. In other embodiments, the coordinator machine <b>30</b> identifies a worker machine <b>30</b>′ and transmits information for accessing the worker machine <b>30</b>′ to the client machine <b>10</b>. In still other embodiments, the coordinator machine <b>30</b> transmits information for accessing the client machine <b>10</b> to the worker machine <b>30</b>′. In one of these embodiments, the coordinator machine <b>30</b> provides no additional information or communication to the client machine <b>10</b> after transmitting the access information associated with the worker machine <b>30</b>′. In yet other embodiments, the coordinator machine <b>30</b> establishes a connection between the client machine <b>10</b> and a worker machine <b>30</b>′.

1212In one embodiment, the client agent <b>8802</b> of the client machine <b>10</b> establishes a connection to the worker machine <b>30</b>′. In another embodiment, the client machine <b>10</b> communicates with the worker machine <b>30</b>′ using a presentation layer protocol, such as ICA, RDP, VNC, or X11.

1213In some embodiments, the worker machine <b>30</b>′ provides access to the requested resource by executing an application on the worker machine <b>30</b>′ and transmitting application-output data generated by the execution of the application to the client <b>10</b>. In other embodiments, as depicted by <figref idref="DRAWINGS">FIG. 97</figref>, the worker machine <b>30</b>′ provides access to the requested resource by providing access to a virtualized environment or by providing access to an application streaming service, as described above in connection with <figref idref="DRAWINGS">FIG. 8</figref>.

1214In some embodiments, upon identification of a worker machine <b>30</b>′, the client agent <b>8802</b> of the client machine <b>10</b> establishes a connection with a session management component <b>1300</b> associated with or residing on the worker machine <b>30</b>′. In other embodiments, the worker machine <b>30</b>′ executes the session management component <b>1300</b> to which the client machine <b>10</b> connects. In one embodiment, the session management component <b>1300</b> queries a virtual machine management component <b>1200</b>, for the location of the configuration and virtual disk files of a virtual machine to run for the current user and a hypervisor in which the virtual machine may execute. In still other embodiments, the client machine <b>10</b> connects directly to the worker machine <b>30</b>′.

1215In some embodiments, the identified hypervisor and virtual machine execute on the worker machine <b>30</b>′. In other embodiments, the identified hypervisor and virtual machine execute on a remote machine <b>30</b>″. In one of these embodiments, the worker machine <b>30</b>′ communicates with the remote machine <b>30</b>″ using a presentation layer protocol to receive output data generated by a resource executed by the virtual machine.

1216In one embodiment, the session management component launches the virtual machine within the specified hypervisor in full screen mode. In another embodiment, a previously-executing virtual machine is allocated to the client machine <b>10</b>.

1217In some embodiments, a virtual machine service component <b>8804</b> executes within a computing environment provided by a virtual machine on a worker machine <b>30</b>′. In one of these embodiments, the virtual machine service component <b>8804</b> receives an IP address and a port with which to establish a communication channel between the session management component <b>1300</b> and the virtual machine service component <b>8804</b>. In one embodiment, this communication channel is used to pass session related configuration information from the client agent session into the virtual machine session. In some embodiments, the configuration information includes display settings and changes, client drive information and authentication data with which to enable single sign-on for a user of the client machine <b>10</b>.

1218In some embodiments, once the communications channel is established and the initial session related information is passed to the virtual machine service component <b>8804</b>, the virtual machine service component <b>8804</b> automatically connects the user to a computing environment, such as a guest operating system, using the same credentials as were provided to the client agent <b>8802</b> by the user (if any). In one of these embodiments, the virtual machine service component <b>8804</b> automatically reconfigures the display settings of the guest operating system to match those of the client <b>10</b>. The virtual machine produces graphics and sound output to virtual devices that redirect that output, directly or indirectly, to the client agent <b>8802</b> on the client machine <b>10</b>. The virtual machine receives audio input, mouse and keyboard device data redirected from the client machine <b>10</b>. When the virtual machine is shutdown or suspended the session management component <b>1300</b> terminates the client agent session.

1219In some embodiments, the coordinator machine <b>30</b> provides functionality for managing a pool of worker machines <b>30</b>′. In one of these embodiments, for example, the coordinator machine <b>30</b> receives information identifying the worker machines <b>30</b>′ as physical machines providing access to particular resources, or as virtual machines providing access to particular resources. In another of these embodiments, the coordinator machine <b>30</b> receives information identifying a plurality of types of resources provided by the pool of worker machines <b>30</b>′. For example, the coordinator machine <b>30</b> may receive information identifying a pool of worker machines <b>30</b>′ as providing access to a type of computing environment, such as a desktop or application. In still another of these embodiments, the coordinator machine <b>30</b> communicates with a virtual machine management component <b>1200</b> to receive information about virtual machines in the pool of worker machines <b>30</b>′.

1220In other embodiments, the coordinator machine <b>30</b> monitors one or more worker machines <b>30</b>′ in the pool of worker machines <b>30</b>′. In one of these embodiments, the coordinator machine <b>30</b> identifies a worker machine <b>30</b>′ to provide access to a resource for a client machine <b>10</b> and identifies a worker machine <b>30</b>″ to provide access to the resource upon a failure of the worker machine <b>30</b>′. In another of these embodiments, the coordinator machine <b>30</b> identifies a worker machine <b>30</b>″ to provide access to the resource responsive to a load balancing technique. In still another of these embodiments, the coordinator machine <b>30</b> identifies a worker machine <b>30</b>″ to provide access to the resource responsive to a change associated with the client machine <b>10</b>. For example, the coordinator machine <b>30</b> may identify a first worker machine <b>30</b>′ to provide access to the resource for the client machine <b>10</b> and the receive a second request for access by the client machine <b>10</b>, after the client machine <b>10</b> has established a connected via a different network, or has lost a first network connection and reestablished a second network connection.

1221In some embodiments, the coordinator machine <b>30</b> identifies a worker machine <b>30</b> that provides access to a resource for a client machine <b>10</b> according to a method chosen responsive to an evaluation of the client machine <b>10</b>, an application of a policy to the client machine <b>10</b> and to the worker machine <b>30</b>′, and an evaluation of the capabilities and requirements of the resource, the client machine <b>10</b> and the worker machine <b>30</b>′.

1222The previously described embodiments may be implemented as a method, apparatus or article of manufacture using programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term “article of manufacture” as used herein is intended to encompass code or logic accessible from and embedded in one or more computer-readable devices, firmware, programmable logic, memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, SRAMs, etc.), hardware (e.g., integrated circuit chip, Field Programmable Gate Array (FPGA), Application Specific Integrated Circuit (ASIC), etc.), electronic devices, a computer readable non-volatile storage unit (e.g., CD-ROM, floppy disk, hard disk drive, etc.), a file server providing access to the programs via a network transmission line, wireless transmission media, signals propagating through space, radio waves, infrared signals, etc. The article of manufacture includes hardware logic as well as software or programmable code embedded in a computer readable medium that is executed by a processor. Of course, those skilled in the art will recognize that many modifications may be made to this configuration without departing from the scope of the present invention.

1223Having described certain embodiments of methods and systems for providing access to a computing environment, it will now become apparent to one of skill in the art that other embodiments incorporating the concepts of the invention may be used. Therefore, the invention should not be limited to certain embodiments, but rather should be limited only by the spirit and scope of the following claims.