AN ARCHITECTURE FOR REAL-TIME MULTIMEDIA COMMUNICATION-SYSTEMS

A multimedia communication system includes both the communication protocols used to transport the real-time data and also the distributed computing system (DCS) within which any applications using these protocols must execute. The architecture presented attempts to integrate these communications protocols with the DCS in a smooth fashion in order to ease the writing of multimedia applications. Two issues are identified as being essential to the success of this integration: namely the synchronization of related real-time data streams, and the management of heterogeneous multimedia hardware. The synchronization problem is tackled by defining explicit synchronization properties at the presentation level and by providing control and synchronization operations within the DCS which operate in terms of these properties. The heterogeneity problems are addressed by separating the data transport semantics (protocols themselves) from the control semantics (protocol interfaces). The control semantics are implemented using a distributed, typed interface, scheme within the DCS (i.e., above the presentation layer), whilst the protocols themselves are implemented within the communication subsystem. The interface between the DCS and communications subsystem is referred to as the Orchestration interface and can be considered to lie in the presentation and session layers. A prototype implementation conforming to this architecture is currently under construction. © 1990 IEEE