Event Correlation: Language and Semantics

Abstract

Event correlation is a service provided by middleware platforms that allows components in a publish/subscribe architecture to subscribe to patterns of events rather than individual events. Event correlation improves the scalability and performance of distributed systems, increases their analyzability, while reducing their complexity by moving functionality to the middleware. To ensure that event correlation is provided as a standard and reliable service, it must possess well-defined and unambiguous semantics. In this paper we present a language and formal model for event correlation with operational semantics defined in terms of transducers. The language has been motivated by an avionics application and includes constructs for modes in addition to the more common constructs such as selection, accumulation and sequential composition. Prototype event processing engines for this language have been implemented in both C++ and Java and are now being integrated with third-party event channels.