What is SOA?

I've been spending the week at a "peer" retreat on Enterprise Architecture in Crested Butte (Colorado). The small event (there are 16 people this year) is organized by Martin Fowler and Bruce Eckel and has been running for several years now.

The participants have historically been J2EE oriented, but more recently there have been some .NET-centric participants. This is the first real opportunity I've had to sit down and talk at length with people from the "other" camp, and it's been tremendously useful for me. Not only that, but guys from Sun and IBM picked up my lunch tab at Brick Oven Pizza yesterday. <grin>

The "sessions" are basically BOFs (birds-of-a-feather) lead by one of the participants, and might include anywhere from 3 to as many as a dozen of us. One interesting breakout the first day was on the topic "What is SOA" and was lead by Bobby Woolf, who co-authored the recent book Enterprise Integration Patterns with another retreat participant Gregor Hohpe. The highlight of that session was Sean Neville breaking everyone up with the line "It's SOAP without the P" (which sounds much funnier when spoken aloud). There were a number of stabs at a real definition of SOA - including one "it's basically an API" that pretty much nobody agreed with. And others by people from a couple of the major players in this area who said "Web Services" which, again, everyone else said was too narrowly focused. One thing that everyone seemed to agree on, though, was that SOA included workflow - and probably BPEL. Hmm...maybe those BizTalk guys are onto something after all. <grin>