Event-Driven Architecture – Thoughts from Practitioners

I’ve been meaning to point out a couple of good posts by practitioners related to my EDA overview post.

In the first post, MarkG over at darth.net excerpted a whitepaper he wrote on real-time integration challenges:

Real time integration brings forth a host of challenges driven by the need to consume business events as they happen. These challenges can be categorized into the following topics: Event Notification, Event Delivery, Event Persistence, Event Recovery, Event Consumption, and Event Monitoring.

Mark brings up some important design considerations. I found myself nodding my head and recalling design sessions with my (at the time) lead architect about how to find lost events. The biggest gap is between the event generator and the initial event persistence. Adding to our challenge, we used the event architecture for system events.

So, what happens when the event code (generator, persistence, processing engine) fails? How would we be informed if we couldn’t generate, persist, or process a system event? Good stuff to think about. There are always answers (bypasses), but the key is to make the right trade-offs. How much are you willing to spend (time, money, overhead) for perfection? What is the risk (business) if you don’t?

In the second post, an anonymous consultant over at Controlled Agility, points out the criticality of traceability in an event system – specifically in a chain of events (parent-child).

To enable traceability you need two more fields in each event header, you need an array of ParentEventIds and an array of SibblingEventIds.

This makes sense. I only caution that event relationships should reflect business relationships (order caused low inventory) rather than technical implementation (order is also high value order).

On a related note, I was pleased to see Joe McKendrick’s supporting post; particularly his agreement

“…that SOA is part of a constellation of strategies she calls the ‘business-driven architecture’.”

The traffic generated by Joe’s post and the strong response to my IT Linchpin post, is a slap in the head for me, it’s time to post more about business-driven architecture. In a perfect world, my BDA book would be done by now, but I got distracted working with Patty…