Distributed Video Presentations

In this paper, we consider a distributed video server environment where video movies need not be stored entirely in one server. Blocks of a video movie are allowed to be distributed and replicated over multiple video servers. Customers are served by one video server. This video server, termed originating server, might have to interact with other servers for downloading missing blocks of the requested movie. We present three types of presentation plans that an originating server can possibly construct for satisfying a customer's request. A presentation plan can be considered as a detailed (temporally synchronized) sequence of steps carried out by the originating server for presenting the requested movie to the customer. Creation of presentation plans involves obtaining commitments from other video servers and the network service provider, as well as making commitments of local resources, within the limitations of available bandwidth, available bu er, and customer consumption rates. For evaluating the goodness of a presentation plan, we introduce two measures of optimality for presentation plans : minimizing wait time for a customer, and minimizing access bandwidth. We present algorithms for computing optimal presentation plans, and compare experimentally their performance. We have also mathematically proved certain results for the presentation plans.