A generic platform for scalable access to multimedia-on-demand systems

Access to multimedia servers is commonly done according to a client/server model where the end user at the client host retrieves multimedia objects fr om a multimedia server. In a distributed environment, a number of end users mag need to access to a number of multimedia servers through one or severa l communication networks. Such a scenario reveals the requirement for a dis tributed access platform. In addition, the demand for multimedia informatio n is increasing beyond the capabilities of high performance storage devices . Therefore, load distribution and scalability issues must be addressed whi le designing and implementing the distributed access platform. This paper i ntroduces a scalable access platform (SAP) for managing user access to mult imedia-on-demand systems while optimizing resource utilization. The platfor m is generic and capable of integrating heterogeneous multimedia servers. S AP operation combines static replication and dynamic load distribution poli cies. It provides run time redirecting of client requests to multimedia ser vers according to the workload information dynamically collected in the sys tem. To support multimedia-on-demand systems with differing quality-of-serv ice (QoS) requirements, the platform also takes into account, as part of th e access process, user QoS requirements and cost constraints, This paper al so presents an application of the generic platform implementing a scalable movie-on-demand system, called SMoD. Performance evaluation based on simula tion shows that in many cases SMoD can reduce the blocking probability of u ser requests, and thus can support more users than classical video-on-deman d (VoD) systems, It also shows that the load is better distributed across t he video servers of the system.