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INTRODUCTION

In a distributed multimedia information system (see figure 1) there is a set of Web-based applications where each application is allocated on a different node of the network and can require the access of media servers for continuous media data retrieval. These continuous media servers can be used by any application running in parallel on a different node of the network. Consequently, the most critical components in the design and implementation of any distributed multimedia information system (using the Internet or any Intranet) are:

1.
advanced authoring and runtime environments provided to create/play multimedia applications.
2.
multimedia storage servers that support continuous media storage and retrieval, and
3.
network subsystems and protocols that deliver media information to the client sites on time according to pre-specified real-time rates.


  
Figure: A Distributed Multimedia Information System
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This paper presents a new set of language constructs as well as a runtime environment that provides low-level support to these constructs during execution. At the language level, this set of language primitives is suitable for the definition of the required QoS and the real-time dimension of the media that participate in a multimedia application. The runtime part is mainly focused on the maintenance of real-time constraints accross continuous media streams and can ensure for example that audio is presented with the required throughput, jitter and latency characteristics, often reffered to as quality of service parameters of the media stream. Thus, it is an approach for deterministic guarantees and provides predictable distributed multimedia applications [1]. The theory behind the runtime part refers only to networks that guarantee end-to-end bandwidth allocation. More precisely, the underlying network must go beyond the best-effort service model and allow flows or streams to reserve network resources. Since the current state of public networks does not provide this service, the work of this paper focuses on high-speed local area networks and Intranets where end-to-end bandwidth allocation can be supported.


next up previous
Next: A TYPICAL DISTRIBUTED MULTIMEDIA Up: A Framework for Creating Previous: A Framework for Creating
Costas Mourlas
1999-12-02