When Gartner started talking about EDA there were numerous debates whether Event Driven Architecture (EDA) was an implementation style of SOA or whether it was a distinct architecture apart from SOA. I originally considered it to be the former, but have now been convinced of the latter. You can implement EDA without SOA, and you can certainly implement as request-reply style of SOA without EDA.
However, surveys done by ebizQ and others have consistently shown that the number one reason for companies adopting SOA is to increase business agility. Reuse is second by a good margin. For this reason Gartner has launched a new Event Processing Summit. A few weeks ago Roy Schulte did an ebizQ webinar on "Event Processing: Competitive Advantage Through Situational Awareness, ", but the title could just as easily been an EDA Primer. If you want to know more about EDA, definitely check it out.
The general idea is that while the communication paradigm for Web services is primarily request/reply, an event drive architecture pushes information out to stakeholders as they occur. In the webinar Roy discusses Complex Event Processing (CEP) and Event-stream Processing (ESP). CEP correlates multiple events in one or a few event streams, and provides "sophisticated pattern detection of event relationships, causality, event hierarchies, multiple layers of abstraction".
Brenda Michelson, ebizQ blogger and founder of Elemental Links implemented an EDA when she was the Enterprise Architect at L.L. Bean. Brenda is another EDA expert I listen to a lot. She defines 3 styles of EDA. There is simple event notification, where something happened and someone is notified, event stream processing where events are filtered and only noteworthy events trigger notification; and complex event processing which applies analytics to detect patterns and even predict behavior. Different types of technologies are used to implement these different styles of EDA.
The business agility SOA delivers is directly tied to loose coupling. EDA maximizes the agility of SOA. On the flip side, using SOA to implement EDA solutions also creates greater technology independence increasing both agility and reuse. Organizations embarking upon their SOA paths should definitely pay attention to EDA.
What is your organization doing about EDA? ebizQ is conducting a research survey on EDA. Take the survey and be entered for a chance to win an iPhone.
To learn more about EDA check out these articles:
"Understanding Event-Driven Architecture", Roy Schulte, Vice President and Distinguished Analyst, Gartner, Inc. and Dr. K. Mani Chandy, Simon Ramo Professor of Computer Science, California Institute of Technology.
"The Role of Event Processing in Modern Business", Dr. K. Mani Chandy, Simon Ramo Professor of Computer Science, California Institute of Technology and Roy Schulte, Vice President and Distinguished Analyst, Gartner, Inc.