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On Tue, 30 Nov 2004 12:21:08 -0600, Bullard, Claude L (Len)
> Are services responses to events?
> That is likely at least one level higher
> in the organizational architecture if call
> and response is the lowest level of description,
I don't think I get the distinction you're making here. Aren't these
orthogonal concerns? That is, one models the Time dimension
independently of the Function dimension  and shouldn't be tightly
coupling the implementation of either to each other?
> but if we are to speak of a 'services oriented
> architecture' that is meaningful beyond the
> most primitive descriptions, it can be useful
> to think in terms of event types over
> messages. Otherwise, a service and a method
> are indistinguishable. I'm not sure the fact
> of using XML to send and return the request or
> the opacity at the boundary are enough to
> distinguish a service from a method invocation,
> remote or otherwise.
Well if they are indistinguishable that sort of makes sense from a
high level architectural perspective. Aren't you starting to tread
into detail design and implementation once you start to try and draw
this boundary? Certainly the physical design enters into the
architecture, but if one is talking about SOA then I don't think one
is specifying the architecture down to the physical level. Rather
you're hitting some of the Data, Function and maybe Time and Network
dimensions at the conceptual and logical levels at best?
IOW, what this thread is circling around is that, currently, SOA is
not a complete "Enterprise Architecture" nor a best practice for
physical or detail design. As an architecture it's incomplete and
thus Tim's initial complaint.
 - http://www.zifa.com/framework.html
(There used to be a cleaner version of this on the site, but it's
still a useful framework for this type of discussion)