A generic platform for scalable access to multimedia-on-demandsystems

摘要

Access to multimedia servers is commonly done according to anclient/server model where the end user at the client host retrievesnmultimedia objects from a multimedia server. In a distributednenvironment, a number of end users may need to access a number ofnmultimedia servers through one or several communication networks. Such anscenario reveals the requirement for a distributed access platform. Innaddition, the demand for multimedia information is increasing beyond thencapabilities of high performance storage devices. Therefore, loadndistribution and scalability issues must be addressed while designingnand implementing the distributed access platform. This paper introducesna scalable access platform (SAP) for managing user access tonmultimedia-on-demand systems while optimizing resource utilization. Thenplatform is generic and capable of integrating heterogeneous multimedianservers. SAP operation combines static replication and dynamic loadndistribution policies. It provides run time redirecting of clientnrequests to multimedia servers according to the workload informationndynamically collected in the system. To support multimedia-on-demandnsystems with differing quality-of-service (QoS) requirements, thenplatform also takes into account, as part of the access process, usernQoS requirements and cost constraints. This paper also presents annapplication of the generic platform implementing a scalablenmovie-on-demand system, called SMoD. Performance evaluation based onnsimulation shows that in many cases SMoD can reduce the blockingnprobability of user requests, and thus can support more users thannclassical video-on-demand (VoD) systems. It also shows that the load isnbetter distributed across the video servers of the system