A Java Middleware for the Development of Actor-based Multimedia Systems over Internet MBone

This paper describes an architectural framework for the development of Internet-based multimedia systems such as interactive and collaborative media on-demand applications. The programming in-the-small level centres on Java and a variant of the Actor model especially designed for time-dependent distributed systems. The programming in-the-large level can be tuned to exploit current real-time and control protocols proposed for the Internet MBone. A multimedia application is modelled as a collection of autonomous and (possibly) mobile media actors interacting one to another to achieve a common goal. Multiple stream synchronisation is based on reflective actors (QoS synchronizers) which filter message transmissions and apply to them application-dependent QoS constraints. Admission control of multiple sessions is delegated to a system Broker. The paper describes the actor framework and discusses its application to the construction of Java Multimedia Studio on-Demand, a multimedia system designed to support playback, recording and editing of multimedia presentations.