Formal semantics of composite events for distributed environments

Abstract

Languages for event specification in centralized systems and their semantics have received considerable attention in the literature. In contrast, very little work exists on extending the semantics of event specification languages to distributed environments. The paper provides a well-defined notion of distributed composite time stamps and their least restricted strict ordering are defined. The ordering is carefully chosen based on mathematical reasoning to ensure the best semantics. The concurrence and weaker-less-than-or-equal temporal relations are also introduced for the expressiveness of ECA rules. Furthermore, a Max operator is introduced for propagating the composite event time stamps. Based on this partial ordering and the Max operator on the time stamps, the semantics of Sentinel composite events is described for distributed event detection.