[UNCLASSIFIED]RE: [clug] Web services / SOA reference

Richard richard_c at tpg.com.au
Fri Dec 16 11:26:25 GMT 2005

Antti.Roppola at brs.gov.au wrote:

>I recently saw a few SOA presentations that were a hommage to the theory that all
>programming problems can be solved by adding another layer of abstraction. The devil
>would seem to be in the detail (boundaries), otherwise all an "Enterprise Services Bus"
>would do is to provide a black-box in which to hide the spaghetti the "before" diagram.
Well, that's sort of true. I tend to think it's a way of slicing up a 
system that you're about to build, rather than explicitly adding cruft. 
The thing for me is that you accept a few principles in your development 
beforehand (if any of these aren't true, then you can very comfortably 
put SOA to one side without further consideration):
a) whatever you build, it will end up as a distributed system of some kind.
b) all distributed systems require IPC.
c) Once we're breaking this problem up into different pieces, we should 
make sure we can reuse the pieces when we're done by tightly regulating 
the IPC interface, and keeping the calling conventions vendor/language 

SOA is all about the interface. All other implications of SOA flow from 
the idea of a strictly defined, open interface, to generally useful 
systems. That's about it. The usual corrollary of "if anyone tries to 
make it more complex then they're trying to sell you something" applies 
here. There are implications at all stages of the software/project 
lifecycle once you start trying to reuse complete systems at a macro level.

For mine, ESB is one of those buzzwords that instantly brands the user 
as a poor imitation of a professional. As you've noted, the ESB concept 
doesn't bear close scrutiny. I feel ESB's just used by vendors who want 
to be a part of the marketing buzz that did surround EAI, and now 
surrounds SOA.

For the record, any EAI, that isn't/wasn't SOA is probably crap. IMO ESB 
vendors are the try hards from the EAI space. Only BEA /might/ have 
claim to something like an "Enterprise Service Bus" - just as soon as 
they nail down what it is (and isn't).

Waaaaaaaayyyyyy too many TLAs in here...


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