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Group communication systems are proven tools upon which to build fault-tolerant systems. As the demands for fault-tolerance increase and more applications require reliable distributed computing over wide area networks, wide area group communication systems are becoming very useful. However, building a wide area group communication system is a challenge.(More)
Fault-tolerant distributed systems are becoming more important, but in existing systems, maintaining the consistency of replicated data is quite expensive. The Totem single-ring protocol supports consistent concurrent operations by placing a total order on broadcast messages. This total order is derived from the sequence number in a token that circulates(More)
Permission is hereby granted to make and distribute verbatim copies of this document without royalty or fee. Permission is granted to quote excerpts from this documented provided the original source is properly cited. ii Abstract When separately written programs are composed so that they may cooperate, they may instead destructively interfere in(More)
This paper presents the architecture and protocols of SMesh, a completely transparent wireless mesh system that offers seamless, fast handoff, supporting VoIP and other real-time application traffic for any unmodified 802.11 device. In SMesh, the entire mesh network is seen by the mobile clients as a single, omnipresent access point.Fast handoff is achieved(More)
This paper describes Transis, a communication subsystem for high availability. Transis is a transport layer that supports reliable multicast services. The main novelty is in the eecient implementation using broadcast. The basis of Transis is automatic maintenance of dynamic membership. The membership algorithm is symmetrical, operates within the regular ow(More)
We formulate a model of extended virtual synchrony that deenes a group communication transport service for multicast and broadcast communication in a distributed system. The model extends the virtual synchrony model of the Isis system to support continued operation in all components of a partitioned network. The signiicance of extended virtual synchrony is(More)
—Contributory group key agreement protocols generate group keys based on contributions of all group members. Particularly appropriate for relatively small collaborative peer groups, these protocols are resilient to many types of attacks. Unlike most group key distribution protocols, contributory group key agreement protocols offer strong security properties(More)
The Spread toolkit is a group communication system available from www.spread.org. Spread provides a range of reliability, ordering and stability guarantees for message delivery. Spread supports a rich fault model that includes process crashes and recoveries and network partitions and merges under the extended virtual synchrony semantics. The standard(More)
Most of the machines that are connected to the Internet are idle a significant fraction of the time. This paper presents the Java Market, a system that allows organizations and Internet users to make use of this wasted computational power. Using the Java programming language and the Web technology, the Java Market is the first metacomputing system that can(More)