A Framework for the Development of Tolerant Real Time Applications

Pedro Sousa and Vasco Freitas

Universidade do Minho
Departamento de Informática
P-4700-320 Braga, Portugal

Tel.: +351 253 604475
Fax.: +351 253 604471
E-mail: {pns,vf} (at) uminho.pt


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 real-time 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.

Keywords: RTP, RTCP, WWW, Plug-ins, Best effort services.

Terena Networking Conference '98 (TNC'98), Dresden, Germany, Oct 5-8, 1998
Computer Networks and ISDN Systems (30)16, pp 1531-1549, Elsevier Science Pub BV, Sep 1998