Method and apparatus for activity-based collaboration by a computer system equipped with a communications manager

(57) In summary book invention, a communication manager provides the communications service for a collaboration system with which the data changing demand including a delta communicates through a network between the devices in which network connection is possible. A communication manager transmits the delta which operated on the local device in which network connection is possible, and was generated at the local place through a network to the remote device in which at least one network connection is possible, Moreover, the delta generated through the network at the remote place from the remote device in which at least one network connection is possible is received. The communication manager can transmit a delta with unicast technology, multicasting technology, or broadcasting technology. A communication manager transmits directly the delta generated at the local place in response to the network connection state information which shows that the remote device in which network connection is possible is connected to a network to the address of the remote device in which network connection is possible. A presence mechanism maintains and distributes the network connection state information acquired from each of the device in which network connection is possible according to a demand. A communication manager transmits the delta generated at the local place according to the network connection state information which shows that the remote device in which network connection is still more possible is cut from the network to the address of a relay. The relay saves the delta and transmits a delta to the remote device to which re connection of the relay was carried out and in which network connection is possible until a relay is notified that re connection of the remote device in which network connection is possible was carried out to the network.