The integration of distributed multimedia systems around the unifying theme of quality of service (QOS) is addressed. A set of key QOS requirements is presented and mapped onto a provisional QOS architecture (QOS-A) that has emerged from a experimental system designed and implemented at Lancaster. The scope of the discussion is limited to aspects of a QOS-A for the support of continuous media communications. Also, the focus is on asynchronous transfer mode (ATM) at the network layer rather than the full range of multiservice networks. Functions and mechanisms for QOS support are examined and placed within the evolving QOS-A. >

Integrated quality of service for multimedia communications

The desire to transfer continuous media such as digital audio and video across packet switched networks imposes a number of new requirements on transport level communication services. This paper identifies a number of these requirements in the context of an experimental distributed multimedia infrastructure, and reports on research which addresses some of the associated issues. Particular attention is paid to two areas: (i) extended Quality of Service (QoS) provision; and (ii) support for the co-ordination of multiple related connections. We then describe an application level service, known as an orchestrator, which performs synchronisation functions over multiple related transport connections. We also outline the design and implementation of a continuous media transport service which meets the identified requirements. Finally, we outline the way in which the orchestrator and transport services are integrated into an object-based distributed multimedia application platform.

https://www.cs.dartmouth.edu/~campbell/papers/sigcomm92.pdf

A continuous media transport and orchestration service

Distributed systems has been an area of intense activity over the past ten years. The subject is entering a stage of maturity with work now focussing on standards for Open Distributed Processing (ODP). However, it is important that standardisation is responsive to new demands on the technology. This is especially true with the emergence of high speed networks in general and multimedia computing in particular. This paper describes research into handling multimedia in the Advanced Networked Systems Architecture (ANSA), a state of the art distributed platform. It is shown that ANSA, although comprehensive in scope, fails to explicitly address multimedia requirements. A number of specific extensions are proposed to remedy these omissions. These include streams, as an abstraction over multimedia protocols, and chains, as a generic control interface to multimedia devices (including storage servers). Importantly, the proposed extensions do not affect the core ANSA architecture, but instead add the necessary functionality in terms of additional services.

E. Zurich

Papers

A multimedia network interface