Peer-to-peer messaging system

Abstract

In one embodiment, a distributed environment for supporting on-line collaborative meetings among a plurality of users includes a plurality of applications executing on different client machines. A sequence of messages is transmitted from a first application of the distributed environment to a second application of the distributed environment, using a multicast form of delivery. A request for re-transmission is received from the second application specifying at least one message of the sequence that was not received by the second application. In response to the request, the specified at least one message of the sequence is retransmitted from the first application to the second application using a reliable unicast form of delivery.

1 - 26 . (canceled) 
   
   
       27 . A method comprising:
 establishing a distributed environment for supporting on-line collaborative meetings among a plurality of users, the distributed environment including a plurality of applications executing on different client machines;   transmitting a sequence of messages from a first application of the distributed environment for supporting on-line collaborative meetings to a second application of the distributed environment for supporting on-line collaborative meetings, using a multicast form of delivery;   receiving a request for re-transmission from the second application specifying at least one message of the sequence that was not received by the second application; and   in response to the request, retransmitting the specified at least one message of the sequence from the first application to the second application using a reliable unicast form of delivery.   
   
   
       28 . The method of  claim 27  wherein the plurality of applications include one or more meeting manager applications and one or more collaboration server applications. 
   
   
       29 . The method of  claim 27  further comprising:
 assigning a respective sequence number to each message of the sequence of messages, and   wherein the request for retransmission specifies the at least one message of the sequence that was not received by sequence number.   
   
   
       30 . The method of  claim 27  wherein the multicast form of delivery is a connectionless multicast protocol. 
   
   
       31 . The method of  claim 30  wherein the connectionless multicast protocol is User Datagram Protocol (UDP) multicast. 
   
   
       32 . The method of  claim 27  wherein the reliable unicast form of delivery is a reliable connectionless unicast protocol. 
   
   
       33 . The method of  claim 32  wherein the reliable connectionless unicast protocol is User Datagram Protocol (UDP) reliable unicast. 
   
   
       34 . The method of  claim 27  wherein the sequence of messages is associated with a subject, and the method further comprises:
 receiving a request from the second application indicating the second application subscribes to the subject.   
   
   
       35 . The method of  claim 27  wherein the establishing further comprises:
 coupling the different client machines with a local area network (LAN).   
   
   
       36 . An apparatus comprising:
 a memory storage device operable to store a first application of a distributed environment for supporting on-line collaborative meetings among a plurality of users; and   a processing device operable to execute the first application, the first application when executed to transmit a sequence of messages to a second application of the distributed environment for supporting on-line collaborative meetings using a multicast form of delivery, to receive a request for re-transmission from the second application that specifies at least one message of the sequence that was not received by the second application, and in response to the request, to retransmit the specified at least one message of the sequence to the second application using a reliable unicast form of delivery.   
   
   
       37 . The apparatus of  claim 36  wherein the first application is a meeting manager application or a collaboration server application. 
   
   
       38 . The apparatus of  claim 36  wherein the first application comprises:
 a sequence number generator operable to assign a respective sequence number to each message of the sequence of messages, and   wherein the request for retransmission specifies the at least one message of the sequence that was not received by sequence number.   
   
   
       39 . The apparatus of  claim 36  wherein the multicast form of delivery is a connectionless multicast protocol. 
   
   
       40 . The apparatus of  claim 39  wherein the connectionless multicast protocol is User Datagram Protocol (UDP) multicast. 
   
   
       41 . The apparatus of  claim 36  wherein the reliable unicast form of delivery is a reliable connectionless unicast protocol. 
   
   
       42 . The apparatus of  claim 41  wherein the reliable connectionless unicast protocol is User Datagram Protocol (UDP) reliable unicast. 
   
   
       43 . The apparatus of  claim 36  wherein the sequence of messages is associated with a subject and the first application comprises:
 a receiver list operable to indicate the second application subscribes to the subject.   
   
   
       44 . The apparatus of  claim 36  further comprising:
 a local area network (LAN) operable to pass the sequence of messages.   
   
   
       45 . An apparatus comprising:
 means for transmitting a sequence of messages from a first application of a distributed environment for supporting on-line collaborative meetings to a second application of the distributed environment for supporting on-line collaborative meetings using a multicast form of delivery, the distributed environment including a plurality of applications executing on different client machines;   means for receiving a request for re-transmission from the second application that specifies at least one message of the sequence that was not received by the second application; and   means for retransmitting, in response to the request, the specified at least one message of the sequence from the first application to the second application using a reliable unicast form of delivery.   
   
   
       46 . The apparatus of  claim 45  wherein the plurality of applications include one or more meeting manger applications and one or more collaboration server applications.