Panel definition language for computer display.

Technical Field

This invention relates to describing, retrieving, modifying, handling and presenting information for a plurality of programs to a display device, and specifically to a screen management system which frees the individual application programmers from the routine programming associated with screens and help messages related thereto.

In the development of a new computing system, many programming tasks, particularly those associated with application programs, must proceed in parallel. At the time of announcement of a new computing system, it is essential that sufficient application programs be available to satisfy customer needs. Potential customers would be unwilling to purchase a new system that, in effect, they are unable to use because of the lack of application programs. It is therefore necessary to develop a variety of application programs at the same time the computing system is under development. Traditionally, application programs for a new system are written by the same programming groups who wrote the previous programs of the same type. This means that each of the application programs for a given system are written by different groups. In the past, this has led to each of the application programs having a different "look" in that the screens have different formats, use different colors for particular classes of information, place the command lines and messages in different locations and generally present a different appearance to the operator. Furthermore, the traditional approach of duplicating display functions in each application program has led to inefficiencies and complexities outside of the display itself. For example, data used by more than one program may be stored by each of the using programs. This occupies additional storage space and requires that each location be updated when a change is made.

The lack of screen uniformity among application software programs developed for a new computing system presents problems in testing the programs. Since each application program has its own code for presenting the information to the display device, this code must be tested for each program, even though its purpose and function is largely redundant. Further, the help messages generated in response to an operator request for assistance with respect to specific fields, etc., must be individually written and tested for each application program.

The difficulties with development and testing are but a part of the problem. The problem is well known even to those who use personal computers for nothing more than hobby or home use. Such systems typically use a variety of application programs from different software sources. When a switch is made from one program to another, the screen format also changes. But the problem may also exist with programs supplied by the same vendor because of the difficulties in simultaneously developing the application programs.

The lack of uniformity in screens is more than just an inconvenience. The situation leads to lower operator productivity, higher error rates, discontented computer operators, and ultimately, to a dissatisfied computer customer.

Background Art

The prior art has been more concerned with the problems relating to accommodation of different display devices on the same system than the lack of uniformity of screens between application programs. The prior art has also addressed the problems which arise when new displays are added to an old system.

Exemplary of the prior art is U.S. Patent 4,586,158 which describes a mapping service which effects the interface between the application program and the physical presentation of the information on the display screen. Simply stated, the program logic of the mapping service transforms the data represented in the format of the application program into another format based on a specified set of rules. There is no suggestion as to how displayed data common to more than one application program could be shared. This system operates to change the stored data in accordance with a set of predetermined rules, and there is no suggestion as to how the data can be specified so as to be uniformly usable by all the display devices and screens without the need for reformatting.

Disclosure of the Invention

A primary object of this invention is to provide a common interface between data shared by a plurality of application programs and a system display.

Another object of the invention is to provide a display-application program interface in which the elements which make up a display, i.e., objects, are specified in generic fashion to allow their use by a plurality of displays and application programs.

It is another object of this invention to provide a display-application program interface which accommodates the use of operator help messages common to more than one application program and display.

Still another object of this invention is to provide a display-application program interface in which the specification of the objects in a given panel provides the basis for the selection of appropriate operator help messages.

These and other objects, features and advantages are realized by an application program-display interface which utilizes tags to reference all objects, which, for example, may be a panel, i.e., a panel title, a single screen of data, instruction lines, data entry areas, menu areas or command lines. Each tag includes a tag name and one or more attributes.

Brief Description of the Drawings

<ul id="ul0001" list-style="none"><li>Fig. 1 is a block diagram representation of the operation of the invention.</li><li>Fig. 2 is an example of a sample list screen developed and managed with this invention.</li><li>Figs. 3a-3f are block diagram representations of the programming aspects of this invention.</li></ul>

Description of the Invention

A screen oriented, high level language is used to define and manage a display screen as shown in Fig. 1. In a data processing system which utilizes a number of application programs, the system programmer will define the screens for a given application program using the high level language as depicted in block 1. This program is then compiled by the compiler 2 which creates the panel group objects 3. The application program 4 interacts with the panel group objects by means of the panel application execution support 5, which accesses the variable pool 6 and interfaces with the device support 7. The display device 8 is operated under the control of device support 7.

"Objects", which are the items placed on the display screen, are designated by means of tags. Each tag may have attributes which further define the nature of the object. Objects which need to be referenced either in the source or at run time by an application program, possess a name attribute. Many objects will also have associated text which immediately follows the tag.

The syntax of a tag follows the format:<img file="EP0333619A2_D0001.tif" />

Text associated with the object.

The fundamental object in the language is the "panel" described by the ":panel" tag. Each panel consists of its text, which is a title, followed by the tagged descriptions of the objects, which make up the particular panel. Such objects include instruction lines, data entry areas, menu areas and command lines. These object may, in turn, be made up of other objects, all described with the same syntax.

Panel definitions are grouped together in source file to form a "panel group". All panels in a group are capable of sharing definitions of other named objects defined in the panel group. All objects which can be shared among several panels, such as function key lists, are used by specifying their names on the appropriate attributes of the panel tag as shown in the following illustration.<img file="EP0333619A2_D0002.tif" />

In addition to panels, other objects are declared in the panel group. These facilitate the definition of panels by providing an encapsulation of some sort of shared characteristic.

"Classes" are used to define a set of common attributes for the data to be displayed on a panel or used for control purposes. They provide a very simple means of data abstraction that can be applied to this data. Characteristics include: - The base type of the values, i.e., packed, binary, etc. - Shift characteristics for input fields for variables of this class. - Number of character positions a value of this class should occupy on a display. - Translation to/from internal value from/to display value. - Checking of values entered on the display to meet certain criteria, i.e., range or specific value checks.

"Variables" define the actual data used by an application in this panel group. Variables are given a name and reference a class. All variables declared in this panel group are collected into a data structure called a "variable pool", manipulated by the application program.

"Conditions" are objects which influence the inclusion of other objects when that panel is displayed. A condition is specified in a "mini-­language" attribute of the condition tag. That condition is then evaluated during application program execution to control the inclusion of panel elements.

"List Objects" provide an object which consists of rows of like columns of data. An application execution interface allows the contents of a particular row to be exchanged with a set of variables from the variable pool. A "List Area" is an object found in the panel which provides the viewing characteristics of this underlying data object.

"Truth Tables" are objects which control the mutual exclusion of conditional items in a panel object. Application program developers use truth tables to provide information to the compile time formatter concerning which of the panel elements are never coexistent on the same panel.

"Key Lists" can be shared among panel objects to define actions which take place on that panel when keys, in particular, function keys, are pressed.

"Panels" at the object that maps to the actual display surface. Panels use, either directly or indirectly, all of the above objects.

The following is an outline for the source describing a set of interactive panels:<img file="EP0333619A2_D0003.tif" />

Fig. 2 shows a sample list panel. The first step in implementing this panel is to define the screen using the tag language. The following tag source produces the desired screen.

The first step in implementing the panel of Fig. 2 is to define the screen using the following tag source producing the desired screen.<img file="EP0333619A2_D0004.tif" /><img file="EP0333619A2_D0005.tif" /><img file="EP0333619A2_D0006.tif" /><img file="EP0333619A2_D0007.tif" /><img file="EP0333619A2_D0008.tif" />

The following describes skeleton help text necessary to support the panel of Fig. 2. It would be stored in a panel group named E1HLPGRP. The help could also be stored in the same panel group object, manufactured supplied help should normally be stored in separate panel group objects so it can be loaded onto the system or not at the user's option.<img file="EP0333619A2_D0009.tif" /><img file="EP0333619A2_D0010.tif" /><img file="EP0333619A2_D0011.tif" /><img file="EP0333619A2_D0012.tif" /><img file="EP0333619A2_D0013.tif" />

The following describes the code necessary to support the previously defined panel. The first thing to be done is to build a structure used to communicate with the variable pool. Space must be allocated by the program for each dialog variable value that will be referenced in the program. This space will be used to specify where to put retrieved values of dialog variables on GETVAR operations and where to get values to update dialog variables on PUTVAR operations.<img file="EP0333619A2_D0014.tif" />

The next step is to invoke the VARLST and VARLSTE macros to build and initialize the variable list data structure(s) required by the GETVAR and PUTVAR functions. To simplify coding later on, two different structures are built. The first structure will be used to communicate with just the INFO variables. The second structure will be used to communicate with the LIST variables.

The following describes the code necessary to build and initialize the INFO variable list data structure.<img file="EP0333619A2_D0015.tif" />

The following describes the code to build and initialize the LIST variable list data structure.<img file="EP0333619A2_D0016.tif" />

The following line will pull in the declaration of constants.<img file="EP0333619A2_D0017.tif" />

After all declarations are completed, the UIM is invoked to start a new application. To do this, the program must code an invocation of macro OPENAPP.

The OPENAPP macro requires two parameters: PNLGRP and APPID. The panel group we wish to open is EXAMPLE1. The OPENAPP macro returns an application identifier into the variable specified for the APPID keyword. The APPID value must be used throughout the program to tell the UIM which open application to use for all requests.<img file="EP0333619A2_D0018.tif" />

Now that the application is open, dialog variables and insert list entries that will appear on panels in the open application can be set.

On the example panel, there are two variables that appear in the information area at the top of the panel. The following code segment shows how to give those variables correct values (before the panel is displayed).<img file="EP0333619A2_D0019.tif" />

The next segment of code shows how the list on the sample panel could be build. The loop control would be conditioned on the number of entries available to insert into the list.<img file="EP0333619A2_D0020.tif" />

If the list is complete, when the workstation operator attempts to scroll past the end of the list, a message is displayed indicating the end of the list has been reached.

If the SETLSTA macro has been invoked using CONTENTS(*TOP), the operator would be allowed to scroll beyond the end of the entries in the list. To accomplish this, the UIM would have returned to the program indicating that more entries were required in the list. At this time, the program would add more rows to the list and redisplay the panel. See 1.5, "Example 5 - A Mixed Panel (Data and List)" on page 52 for an example of incomplete list processing.

For this example, it is assumed that all entries have been added to the list. Since the UIM has now been given all information necessary to present the panel, we need only invoke the DSPPNL macro to display the panel to the work station operator. In this example all scrolling, action list processing, help displays, and command prompting and execution are handled by the UIM. Control only returns to the program when the operator presses a function key to PREVIOUS, EXIT, or REFRESH the display, or when the operator presses ENTER and there are no action list items or commands to process.

The FUNCTION parameter on the DSPPNL macro returns an indication of what function was requested that terminated the display. The program variable on this parameter is set with a value that indicates what function (PREVIOUS, EXIT, REFRESH etc.) is expected of the program.<img file="EP0333619A2_D0021.tif" />

After the panel has been displayed, and control has returned to the calling program, the variable specified for the FUNCTION parameter can be checked to see what caused the return to the program.<img file="EP0333619A2_D0022.tif" />

From the example panel, a typical user may select the CHGSPLFA command (option 2) for one of the list entries to change the attributes of a spooled output file in the list. After the command is executed, the list needs to be updated to reflect the change.

To change the list entry, an exit program could be invoked. The name of the exit program is provided on the LISTACT tag with the USREXIT parm. The following is the code the EXIT program would probably run to reflect the change in the attributes. The exit program assumes that the list is already positioned at the appropriate entry and the dialog variables already contain values for this list entry because the UIM positions the list and reads the entry before it invokes the action routine and exit program.<img file="EP0333619A2_D0023.tif" />

After all processing is done for the list (the user may have pressed the PREVIOUS key) the application should be CLOSED. The code necessary to close the application is as follows.<img file="EP0333619A2_D0024.tif" />

With reference to the programming data flow charge of Figs. 3a-3d, which show the sequence of functional operations effected by the program instructions, operation of the program begins block 500 when the application program opens the panel group. The application program has to be told which set of panels is going to be used, in other words, a name is given to the panel group to be handled. The application then goes into the main loop via block 501, where it sets the value of the variables in the variable pool. The variables are a set of values that are identified by their names and they can hold values which are data that the application can use. The values are set by referring to data in the application program and copying this data into the variable pool.

The display panel service of block 503 is that which actually performs the display of the panel. The following decision block 505 is actually in the display manager itself. The function of this block is to validate the request and make certain that the panel requested is the panel group.

In block 503 the application retrieves values that the user has altered on the display and does this by accessing the variable pool again and pulling these values out. This process is repeated by the decision made in block 504, which returns the program to block 501, until all variables have been retrieved.

When the application is complete, the decision in block 504 passes the program to block 506, where the application closes the panel group.

The display leg of the program begins with block 510, in which the conditions being used on the panel are checked. This step gathers up the conditions which are to be evaluated for the panel under consideration. Each panel has a distinct set of conditions. The panel language has a separate language inside of it for defining conditions that can be used to exclude or include elements onto a panel for display. Examples include function key definitions, which may be excluded from the screen, and thereby hold the function key in the inoperative state. The help text relating to the excluded function key is also blocked from display. Thus, when an object has been excluded, there is no remnant of that object.

In block 511, the conditions are evaluated, referencing the values that are in the variable field as well as system objects. An example of the latter category would be an item on the main menu of the system. It might be desirable to exclude certain menu items if the user does not belong to a class which, for example, is allowed to write into a particular field.

In block 512 the actual elements to be displayed are examined, and, in block 513, the decision is made as to whether the object is to be displayed. Each object may be conditioned or not. If it is not conditioned, it is displayed. If it is conditioned, the value of the condition is checked and, if it is true, the object is included for display.

Objects are assigned their appropriate positions on the display in block 514. The tentative position is assigned at compile time. The final position is subject to verification in this block.

Appropriate attributes are assigned to each object in the operation of block 515. Highlights, color and things of that nature are mapped to the display in accordance with the type of object, such as an instruction line.

The decision in 516 relates to determination of whether a variable value is involved for the particular object under consideration. Some objects, such as menu items, do not have a variable value and therefore do not require anything to be retrieved. Other objects, for example, data items, have displayed values which are given through the variable pool, necessitating an access to the pool, as shown in block 517, to retrieve the object for display. Any required conversion is also performed in this block. For example, a value may be stored in binary form and must be converted to decimal for display.

After this process has been completed for all objects on the display, as determined by block 518, a data stream is constructed from the developed list of objects and positions as shown in block 519. If all objects have not been considered, the program loops back from block 518 to the input of block 512, considering all objects in turn.

Therefore, at point A there has been established a new data structure which is essentially a list of all objects to be displayed with their attributes. The data stream is sent out to the display device in block 520. The data stream is interpreted and presented to the user by the display device. At block 521, the user views the screen, fills in the appropriate information and presses a function key to send the entered data, in the form of a data stream, back to the system, at block 522.

The data stream, as before, consists of locations and values. The operation at block 523 requires an examination of the function key pressed in block 521. If the function key related to a variable which is to be updated, the test at block 523 leads to block 524, which correlates the screen location with a particular object. Having identified the object involved, the object is examined in block 525 to see which of the variables in the variable pool is involved. The variable class is then checked to block 526 to see if there is any validity checking involved for the particular variable under consideration. If checking is involved, block 527 is entered and the appropriate checks are performed.

Block 528 operates in the result of the check. If the check failed, the process passes to block 529 where the entered value is tagged as an error. The data tagged as an error is then reshown on the display, block 530, and the work station user is given the opportunity, in block 531, to reenter the data correctly. Since the user may have made another error, the program returns to block 522 and the checking process is repeated to ensure that the new data is correct.

When the entered data passes the validity check, the operation of block 532 causes the variable value to be updated and the program loops back to the test in block 523 to see if all the variables have been updated. Eventually, the variable updating process is completed and the test in block 523 indicates that there are no remaining variables to be considered. The program then proceeds to block 540, where the function keys are examined to determine what dialog action is to take place. This is accomplished by mapping the function keys to the appropriate dialog action.

If the dialog action implies a return to the application, the test in block 541 passes to block 542 which effects the return to the application as shown. If other dialog action is indicated, the test performed in block 543 is performed to see if the dialog action is help. If the help action is requested, the block 544 begins the determination of what help was requested by determining the cursor position and correlating it to a specific object. Next, the display object identified in block 544 is tested to see what sort of object it is. The test in block 545 determines whether or not the object being evaluated was a command line.

If this test indicates that the object under consideration is a command line, the test in block 546 determines whether or not a command has been entered. If there is an entered command, block 547 serves to invoke run time support and display the help message for the specific command. If no command has been entered, the test of block 548 determines whether the command line had a menu option. If so, the block 549 selects the menu item as the object for the purposes of determining which help message should be displayed.

If the selected object is not a command line, as determined in block 545, or is not a command line with a menu option, as determined by block 548, the action in block 550 serves to display help for the selected object.

At block 560, a help list is constructed corresponding to all the objects on the panel, excluding those objects which were conditioned out. The first and last items on the list for which help is to be displayed first are so marked. In the usual case, this will be a single item corresponding to the selected object.

In block 561, the help application is invoked to display the help panels which are needed to get the help panel for the particular user panel. If, at this point, the user presses a function key requesting extended help, block 562 transfers operation to block 563 which presents extended help to the user. This will generally be all the help messages relating to all the objects identified. The user than takes appropriate action, for example, indicates that the use of the help message has been completed, as depicted in block 564, and the program returns to point A.

Returning now to block 543, if the test indicates that the dialog action is not help, block 570 tests to see if the dialog action was something which can be handled directly by the display manager, such as rollup, rolldown, or change view. If it is, runtime support performs the function and the program returns to point B as shown in block 571.

If the test in block 570 indicates that it is not a dialog action which can be handled directly by the display manager, block 580 looks to see if it is a command request. If it is, the request is submitted to the system in block 581 and the program returns to point A. If it is not, block 582 is entered and either a return to the application occurs or the panel is reshown, depending on how the user coded the panel to handle a null situation.