An Event Service Framework for Distributed Real-Time Systems

Many distributed systems use events for asynchronous communication. Although the CORBA Event Service provides a flexible model for event-based communication among objects, further work is needed to support the important features required by real-time applications such as network management, avionics, etc. where timely delivery of events and more complex event correlation are desirable. In this work, we identify a set of real-time event service requirements that are found in a distributed environment, i.e., event registration, composite event specification, event timing constraint specification and timely composite event detection and event dispatching. We propose the design of a Real-Time Event Service Center object as a top-level architecture for event services. We then focus on one of the key issues in this architecture: the specification, compilation and detection of composite events. A specification language for composite events is proposed in this paper and the problem of how to efficiently detect the occurrence of these composite events as early as possible is investigated in [13, 19]. To justify the practicality of our approach, a Java package is being developed to specify, compile and detect various composite events. We outline the architecture of this pack-