Using the Java Media Framework to build Adaptive Groupware Applications

Realtime audio and video conferencing has not yet been satisfactorily integrated into web-based groupware environments. Conferencing tools are at best only loosely linked to other parts of a shared working environment, and this is in part due to their implications for resource allocation and management. The Java Media Framework offers a promising means of redressing this situation. This paper describes an architecture for integrating the management of video and audio conferences into the resource allocation mechanism of an existing web-based groupware framework. The issue of adaptation is discussed and a means of initialising multimedia session parameters based on predicted QoS is described

The ISIS project: Fault-tolerance in large distributed systems

The semi-annual status report covers activities of the ISIS project during the second half of 1989. The project had several independent objectives: (1) At the level of the ISIS Toolkit, ISIS release V2.0 was completed, containing bypass communication protocols. Performance of the system is greatly enhanced by this change, but the initial software release is limited in some respects. (2) The Meta project focused on the definition of the Lomita programming language for specifying rules that monitor sensors for conditions of interest and triggering appropriate reactions. This design was completed, and implementation of Lomita is underway on the Meta 2.0 platform. (3) The Deceit file system effort completed a prototype. It is planned to make Deceit available for use in two hospital information systems. (4) A long-haul communication subsystem project was completed and can be used as part of ISIS. This effort resulted in tools for linking ISIS systems on different LANs together over long-haul communications lines. (5) Magic Lantern, a graphical tool for building application monitoring and control interfaces, is included as part of the general ISIS releases

A framework for the development of tolerant real time applications

This work presents a framework architecture for the development of distributed real-time applications to be integrated into WWW clients. It assumes a WWW environment over networks providing a best-effort delivery service like the internets based on the IP protocol. The framework is that of an application programming interface (API) providing the program developer with the services needed by tolerant realtime applications. Once developed, an application is bundled together with the API to form a WWW plug-in which can subsequently be called from a WWW client interface or browser. The application is then perceived as being integrated into the WWW environment. The design aims to provide real-time applications with a transport service layer assuring near end-to-end isochronism despite the weak guaranties of the underlying network service. The implementation of the mechanisms that allow multistream real-time communications to adapt to the operational conditions of these networks are discussed. In this work, the RTP and RTCP protocols were also implemented as part of the API. Experience with this framework reports the development of a prototype real-time application for multimedia group communication and the analysis of the behaviour of RTP sessions in a real operational situation. The analysis uses protocol state data logged during their operation