WSDL and BPEL extensions for Event Driven Architecture

ContextService Oriented Architecture (SOA) and Event Driven Architecture (EDA) are two acknowledged architectures for the development of business applications and information systems, which have evolved separately over the years.ObjectiveThis paper proposes a solution for extending the SOA/Web Services Platform Architecture (WSPA) with support for business events and EDA concepts. Our solution enables services to act as event producers and event consumers. It also enables event-driven service orchestrations in business processes.MethodBased on a comparison of SOA and EDA, we have identified and designed the required extensions to enable support for events and event-driven process orchestration in WSPA.ResultsWe propose specific extensions to WSDL and BPEL, and a flexible XML representation of the event payload data. We introduce event sinks, sources, and triggers to WSDL. We extend BPEL with new activities to trigger and catch events, and extend fault and event handlers, variables, and correlation properties to accommodate events.ConclusionAs a proof-of-concept, we have developed a prototype implementation and assessed the extensions on three pilot projects. We have shown that our proposed extensions work on real projects and that combining event-driven and service-oriented semantics makes sense in many business applications and can considerably reduce the development effort.