A configurable event service for distributed systems

Event services are needed for control systems, implementing management of networks and distributed and event based applications. In all these applications it is necessary to filter out unwanted events and combine low-level event sequences into a higher level, more abstract event to trigger an action. In this paper we present a flexible and powerful distributed event service which can be used to process and disseminate events for many different applications. The service can be configured dynamically at two levels. Composite events can be defined as rules in terms of event sequences using the GEM notation. These rules can be loaded, removed, enabled and disabled dynamically within event monitoring interpreters. Interpreters and event disseminator components can then be dynamically configured onto physical nodes within the system using the Darwin configuration environment to distribute the monitoring close to where events are generated. This reduces network traffic caused by event generation in large systems.