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RE: Definition of Choreography

From: Mathews, Walden <walden.mathews@tfn.com>
Date: Thu, 17 Oct 2002 16:34:25 -0400
Message-ID: <1373D6342FA1D4119A5100E029437F64045EEE14@clifford.devo.ilx.com>
To: "'David Orchard'" <dorchard@bea.com>, "'Mark Baker'" <distobj@acm.org>, "'Champion, Mike'" <Mike.Champion@softwareag-usa.com>
Cc: www-ws-arch@w3.org

'Determinate' might be a good word there, instead of 
or in addition to 'turing complete'.

WM

> -----Original Message-----
> From: David Orchard [mailto:dorchard@bea.com]
> Sent: Thursday, October 17, 2002 4:26 PM
> To: 'Mark Baker'; 'Champion, Mike'
> Cc: www-ws-arch@w3.org
> Subject: RE: Definition of Choreography
> 
> 
> 
> 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.
> 
> Cheers,
> Dave
> 
> > -----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
> > 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 16:35:05 GMT

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