SOLIDOR - Publications

Title:	A proposal for ensuring high availability of distributed multimedia applications
Authors:	Manuel Billot, Valérie Issarny, Isabelle Puaut, Michel Banâtre.
Authors' address:	IRISA, Campus de Beaulieu, 35042 Rennes Cedex, FRANCE

Abstract: Recent advances in computing, like high-speed networks and data-compression, make extensible distributed multimedia applications a challenging application-domain of distributed systems. Such applications like VoD (Video on Demand) or real-time conferencing are characterized by QoS (quality of service) requirements which depend on:

the quality of video and sound transmitted to the client;
the respect of time constraints associated to video and audio data.

Much work has been done in order to provide system support aimed at meeting these requirements. However, existing proposals do not integrate the consequence of failure occurrence on the guaranteed QoS. To deal with this issue, we propose a resource reservation model that integrates availability requirements of multimedia services in addition to the QoS constraints introduced above. Our design goals for this model are:

to bring a flexible and simple resource management method: this method should allow application programmers to reserve resources with respect to various requirements including both QoS and availability;
to preserve the transparency of mechanisms used for availability;
to provide a model that allows to meet time-constraints during failure occurrences: mechanisms used for availability usually reduce the application performances, which can lead to miss time-constraints in the case of multimedia applications.

Our paper details the resulting model together with its integration in a distributed system. In particular, we show how the model implementation can be customized in the case of a VoD server.

Paper available in postscript form (121K).