Service and Event Design

Events

For our purposes, an "event" is a message that carries a particular type of business data. An "event" is therefore a message that indicates that a real-world business event has occurred. Events may be high-level, without application dependencies, such as "request customer billing address"; or they may be low-level and application specific, such as "update billing address in SAP". They may be requests for which responses are expected (as is typically thought of in service-oriented architecture), or fire-and-forget notifications that a business event has occurred. They may be delivered synchronously or asynchronously.

Perhaps most importantly, they can be delivered over any communication mechanism, with any enveloping of information. SOAP, EDIINT, ebXML, HTTP, FTP, and many other communication mechanisms may carry any number of different events.

Services

For our purposes, a "service" is a process associated with an event. People often think of services as request-reply, but events need not be: in that sense, service-oriented architecture is a special case of event-driven architecture, and all iWay technology applies to request-reply service-oriented integration as well as event-driven integration. "Composite services" are a special type of service that builds on other, lower-level services. Much of the effort in service-oriented integration is creating composite services that can be reused by a variety of other applications.