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RE: Definition of Choreography

From: David Orchard <dorchard@bea.com>
Date: Thu, 17 Oct 2002 13:26:02 -0700
To: "'Mark Baker'" <distobj@acm.org>, "'Champion, Mike'" <Mike.Champion@softwareag-usa.com>
Cc: <www-ws-arch@w3.org>
Message-ID: <013001c2761b$6a15bfc0$0100007f@beasys.com>

When i said Turing complete, I mean distinguising between two styles of
choreography.  A choreography can specify an order between two nodes.
Imagine that a node sends Messages M1 or M2 depending upon some particular
variable.  In a non-turing complete, the choreography would say M1 or M2.  A
turing complete choreography language would say something like If C1 then
send M1 else send M2.


> -----Original Message-----
> From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]On
> Behalf Of Mark Baker
> Sent: Thursday, October 17, 2002 6:06 AM
> To: Champion, Mike
> Cc: www-ws-arch@w3.org
> Subject: Re: Definition of Choreography
> 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
> 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 16:30:29 UTC

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