A framework for event composition in distributed systems

1 Introduction Event-based communication has become a new paradigm for building large-scaledistributed systems. It has the advantages of loosely coupling communication partners, being extremely scalable, and providing a simple application program-ming model. In event-based systems, events are the basic communication mechanism. An event can be seen as a notification that something of interest hasoccurred within the system. Components either act as event sources and publish new events, or event sinks and subscribe to events by providing a specificationof events that are of interest to them. A publish/subscribe (pub/sub) communication layer 1 is then responsible for disseminating events; for efficiency, it canoften also filter events by topic or content, according to client specifications.