Group Communication Support for Distributed Multimedia and CSCW Systems


The Collaborative Computing Transport Layer (CCTL) is a communication substrate consisting of a suite of multiparty protocols, providing varying service qualities among process groups. We have designed CCTL explicitly to support the needs of distributed collaborative and multimedia applications. CCTL is based on a two-level group hierarchy. Logical interconnections among entities, called channels, define an efficient and lightweight group mechanism. Channels support a variety of service qualities such as reliability and message ordering. Related channels can also be combined to form sessions, heavy-weight groups which provide a default atomic multicast service. The CCTL architecture supports various membership protocols, including a relaxed form of virtual synchrony, tailored to the quality of service offered by a particular channel. Our two-level architecture allows simple and efficient implementation of the membership protocols. In this paper, we present implementations of CCTL and compare and relate our implementations to alternative approaches.

Index: Distributed Systems Architecture, Group Communication, CSCW, Multimedia, Membership Protocols, Virtual Synchrony.
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