Formalizing Multimedia QoS Constraints Using Actors

The vision of future information systems is that diierent forms of information are potentially accessible at anytime through the Internet. We describe challenges in the modeling and speciication of timing related multimedia (MM) services in open distributed systems. Management of multimediaservices in an open system is complicated by the heterogeneity of application requirements, multimedia information, and system components. Services and systems in this environment evolve dynamically and their components interact with an environment that is not under their control. We propose a formal speciication of timing related Quality-of-Service (QoS) attributes in an actor-based distributed system and describe some techniques for informally reasoning about quantitative QoS properties. 1 MOTIVATION Services and systems in a global information environment like the WWW evolve dynamically and their components interact with an environment that is not under their control. Many multimedia (MM) applications can tolerate relatively minor and infrequent violations of their performance requirements; the extent to which such violations are permissible is speciied as a quality-of-service (QoS) parameter. In this paper, we discuss preliminary work on the speciication and semantics of timing based Quality-of-Service (QoS) parameters in multimedia applications. Our goal is to provide formal speciications of QoS in a distributed MM system and thereby reason about the formal val