A Semi-Distributed Platform for the Support of CSCW Applications

This paper describes the communication platform that was implemented for the European BETEUS (Broadband Exchange for Trans-European Usage) project. The BETEUS communication platform supports the fast implementation of networked multimedia applications with conference character and CSCW (Computer Supported Collaborative Work) features. The platform exhibits the notion of a site as one of its main abstractions. A site is a collection of workstations, media input and output devices and switching devices that are, in terms of control, tightly coupled. The available equipment within a site is logically mapped onto nodes, where the definition of a node is application dependent. Connection control in a site is centralized within a connection management entity. A site management entity residing on top of the connection management provides high level connection and session abstractions to applications. Applications can run within a site as well as span multiple sites, in which case application and connection control is distributed among the involved sites. So far, two applications have been implemented on top of the platform: a telemeeting application and a tele-tutoring application. The ease with which these applications could be implemented justifies the extra-effort that went into the development of a platform.