Netscape Communications Corporation

John Richard Stracke, Jr

A distributed locking apparatus for a collaborative computing system permits members of a collaborative session to obtain and transfer a lock without the use of a central lock server. Each member of the collaborative session has a lock engine, which transitions among four states depending on the location of the lock. An Available state indicates that the lock is available. A Pending state indicates that the member has requested the lock. A Held state indicates that the member currently holds the lock. A Locked state indicates that another member currently holds the lock. A message structure permits the members to obtain and release the lock and to resolve conflicts over the lock between members of the session.

Method and apparatus for a distributed locking system for a collaborative computer system

A unifying push framework in a computer network environment uses a plumbing approach wherein a 'pipe' (producer) is created to interpret a specified push protocol. Push Universal Resource Locators (PURLs) (the streams) are delivered from a server across the computer network to each pipe that handles the specific protocol which interprets the protocol and delivers the stream to the subscribing client (consumer). Several pipes can be combined and clients can subscribe to several different protocols. These pipes are capable of delivering streams to multiple clients and are created dynamically as each client subscribes to different protocols. Filters are easily added and removed dynamically to or from the system to filter streams. A filter can be added to the output side of a pipe before distribution to the clients and/or added before the client to filter the incoming stream, allowing for a flexible system with multiple filtering schemes.

Multiple push protocol unifying system

A router discovery system for virtual routers automatically builds a multicast virtual network over an existing network topology. The virtual routers send out 'heartbeats' across the Internet Protocol (IP) multicast network marked with a Time to Live (TTL) value containing the number of hops that the packet can take through the network before it gets discarded. The originating router gets an estimate of how far away the receiving router is when it receives the response packet from the receiving router (i.e. the receiving router is less than TTL hops away from the originating router). The invention uses the TTL values to find the closest routers. It balances the efficiency of the IP network connections with the distance of the routers to create a balanced network topology and establishes connections with the routers that meet these criteria. When a router comes alive, it sends out multicast packets across the network. Any routers that pick up the packets wait for a random amount of time and after the waiting period, if a router does not hear from any of the other routers that a connection was made, it establishes a connection with the new router. Ping messages are periodically sent between the routers that have established connections between themselves, testing the connection between the routers. The invention automatically and dynamically adapts to changes in the network topology. If a virtual router finds a more efficient connection to another router, it drops the less efficient connection. When a router goes down, the router's neighbors opens up connections to their next-nearest neighbors until the connectivity of the virtual network is restored.

Virtual router discovery system

A collaborative computing system includes a plurality of collaborative computing participants, connected over a network. Each collaborative computing participant has a workstation that includes a conference engine, which provides a network interface between applications and the network. The applications are organized into application modules, each of which provides a collaborative computing function. Either the conference engine or the application modules fragment a data packet to be sent to other participants into a set of equally-sized cells. The cells are transmitted individually over the network via switching entities, which can be other participants in the collaborative session. Each switching entity maintains a list of connections from itself to other switching entities.

Growing community of inventors

Santa Clara, CA, United States of America

John Richard Stracke, Jr