Event-based Programming Structures for Multimedia Information Flows

In this paper, we propose a programming model based on ‘timed event dissemination’ for structuring a distributed real-time multimedia presentation. In this model, event notifications capture program-generated actions and/or user-level object accesses on a multimedia window. A coherent effect of these actions requires enforcing deadlines on the event processing over prescribed time intervals. To meet this requirement, the paper advocates an integration of the ‘flow of time’ as part of the semantics of data presentation on a multimedia window. The paper explores a programming paradigm for event processing: causal ordering of timed messages, to realize multimedia data presentations. This yields simplicity and uniformity in the programming structure of multimedia applications. The presentation specifications in our model can be easily and accurately mapped onto system-level QOS parameters (such as network delays and play-out buffer delays) for scheduling purposes. This in turn may lead to an optimal use of the system resources by a multimedia presentation protocol. The generality of our event-oriented programming interface also allows reducing the multimedia system development costs through software reuse.