In the latest post on the MEST thread, Chris Ferris says:

IMO, the semantics of messages in pub/sub aren't ProcessMessage, they are (or should be) more along the lines of SomethingInterestingHappened. Note the past tense. I think that is the key to achieving a loosely coupled enterprise.

I think the proposed name SomethingInterestingHappened (intentionally) leaves out the imperative and that's wrong. I'm not aware of any MustUnderstand semantics in the traditional message passing systems, and that's perhaps exactly what SOA(P) gives us. In other words, ProcessMessage represents a way for a sender of a message to be sure the recipient will do what the sender says (given compliant SOAP processors).

Provoked by a comment, Chris introduces pub/sub into the MEST debate of what the SOA interface is/should be. While I agree pub/sub is often very useful, it's just one thing that could be done with what people call ProcessMessage semantics. Others include providing a wxf:Get operation on services.

Posted at 1825 on Tue, Feb 1, 2005 in category Ideas | TrackBack | Comments feed

Hi Jacek. So far I haven't seen anything that backs up your statement that "ProcessMessage represents a way for a sender of a message to be sure the recipient wil do what the sender says". All it says is that a receiver gets a message; what it does with that message is implementation specific. OK, you'd kinda hope it would do something based on the content, but it could just junk it, perform some internal transformation on it, or anything. ProcessMessage doesn't say what the implementation does at all.

Posted by: Dave Corne at February 2, 2005 12:38 AM

ProcessMessage isn't a useful architectural approach. It's too low level in one manner and too darn obvious in another - everything is based on messages. Hey, why don't we retrofit this to COM, DCE, CORBA and even J2EE?! They'll all map afterall. It just doesn't say anything about loose-coupling that it couldn't easily say for close-coupling too. But pub-sub is different; it's a naturally understood paradigm that's worked well for decades.

Posted by: anon at February 2, 2005 12:44 AM