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Re: Definition of Choreography

From: Mark Baker <distobj@acm.org>
Date: Thu, 17 Oct 2002 09:06:14 -0400
To: "Champion, Mike" <Mike.Champion@SoftwareAG-USA.com>
Cc: www-ws-arch@w3.org
Message-ID: <20021017090613.D27626@www.markbaker.ca>

On Wed, Oct 16, 2002 at 09:50:12PM -0400, Champion, Mike wrote:
> I think of "Choreography" sortof like a policy, not a program.

I agree.

But David said something that suggested that it was defining the *how*,
not just the *what*; "specification of ordering of messages".  If it
were to define the *what*, I would expect it to say something like;
"The specification of potential state changes".

In most cases, there are multiple possible sequences of messages
that could result in a desired state change.  As a trivial example,
any sequence that included an HTTP GET message, could include an
arbitrary number of HTTP GETs.  i.e. POST-GET-POST is equivalent to
POST-GET-GET-GET-GET-POST.

Also, the mention of turing completeness suggests *how*, rather than
*what*, though I'm a bit unclear about its intent due to the use of the
term "message exchange pattern" (which presumably means something
different than a SOAP MEP - perhaps "message exchange sequence"?)

On the plus side, I like that it's short. 8-)

MB
-- 
Mark Baker, CTO, Idokorro Mobile.  Ottawa, Ontario, CANADA.
http://www.markbaker.ca             http://www.idokorro.com
Received on Thursday, 17 October 2002 09:04:39 GMT

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