Making a database system active entails developing an expressive event specification language with well-defined semantics, algorithms for the detection of composite events, and an architecture for an event detector along with its implementation. Thii paper presents the semantics of composite events using the notion of a global event history (or a global event-log). Parameter contexts are introduced and precisely defined to facilitate efficient management and detection of composite events. Finally, an architecture and the implementation of a compositeevent,detector is analyzed in the context of an object-oriented active DBMS.
Sharma Chakravarthy, V. Krishnaprasad, Eman Anwar,