Eventlets: Components for the integration of event streams with SOA

Cyber physical systems (CPS) react to changes in the environment and have become widely adopted in many domains. One key functionality to achieve this reactivity is the processing of event streams. To profit from this reactive behavior in service-oriented architectures (SOA), event stream processing needs to be encapsulated in a service-like manner. We thus introduce the concept of event applets, in short Eventlets, to provide developers and architects alike with a generic and reusable component model for encapsulating event stream processing logic. Eventlets have a managed lifecycle and are activated automatically upon arrival of appropriate events. We introduce our distributed Eventlet middleware architecture and implementation based on industry-strength message-oriented middleware. Our evaluation shows that Eventlets simplify the development of reactive components and that they can compete with traditional event processing approaches in terms of performance. Eventlets enable easy distribution of event stream processing components and are a suitable foundation for scalable applications that combine SOA with CPS.