Client-server computing requirements of networked multimedia services

The client-server programming model has traditionally supported numerous data applications which can tolerate delay and jitter bounds. The quality of service (QoS) concept is mandatory for multimedia associations since it expresses the application requirements towards the communication subsystem. The application developer should be provided with a mechanism to select and control those QoS parameters that are applicable to the context of continuous media information transfer. As a consequence, the application programmer can easily express his requirement for a multimedia multiparty call. At the user perception level, diverse QoS parameters are issued, which should be interpreted on specific performance parameters by the communication subsystem. Dynamic management of QoS parameters should be provided either at the association establishment phase or at the data transfer phase. The QoS parameter tuple identifies the entire multimedia association in space (i.e. end-to-end) as well as in time (i.e. during the lifetime of the association). This paper discusses the main weaknesses of existing client-server programming interfaces and proposes enhancements that should take place to achieve appropriate computing for the development of multimedia networked services in view of new high-speed network technologies. Furthermore, the attractive features of new multimedia multiparty programming interfaces are presented and analysed.