Applications are now highly distributed, heterogeneous and scalable. They comprise autonomous, loosely coupled components, some of them being database management systems, web servers, etc. Considering such a framework, database technology has to evolve towards cooperation and integration. We propose open and distributed active services that can be used for specifying and generating event and rule managers that support cooperation and interaction between distributed database software (i.e., applications, systems). Event managers are brokers supporting anonymous event passing communication. Rule managers are able to support global (business) rules and execute them using different policies adapted to specific application needs. Both managers can reconfigure and adapt themselves with respect to applications requirements and to their environment. 1

This paper proposes an approach to building event services for active database applications. It introduces dimensions to characterize distributed event definition, detection, production and notification.

This paper presents an architecture of a component based active mechanism suitable for federated database systems (FDBMS), i.e., a collection of autonomous DBMS with a common understanding of their universe of discourse. The main components of the mechanism are flexible event and rule services that cooperate to execute active rules. The event service allows the specification and generation of event managers that detect, produce and notify events using an event management model. The rule service manages Event-Condition-Action rules global to federated database systems. Rules are triggered by events notified by event managers. Conditions and actions can concern multiple DBMS. The execution model of a rule is adaptable to the different component DBMS characteristics.