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RE: Web Service Definition [Was "Some Thoughts ..."]

From: Cutler, Roger (RogerCutler) <RogerCutler@chevrontexaco.com>
Date: Mon, 25 Feb 2002 07:54:50 -0800
Message-ID: <3B286631A9CFD1118D0700805F6F9F5A066F8648@hou281-msx1.chevron.com>
To: "'Mark Baker'" <distobj@acm.org>, "Cutler, Roger (RogerCutler)" <RogerCutler@chevrontexaco.com>
cc: steve.vinoski@iona.com, Mike.Champion@softwareag-usa.com, www-ws-arch@w3.org
I don't see your voting service as having multiple responders.  It seems to
me that you have one web service to which you say, "Please send out a vote
request" and it sends a vote request to multiple recipients.  Now, if the
voting itself is handled as a web service, each of those recipients now
becomes a responder, sending the vote back as a single web service.  The
entire process being a "voting orchestration", I guess.

I wouldn't personally mind making orchestrations web services, but the drift
I have heard from most people is that they don't want to -- although I also
hear that we should consider them architecturally as part of the environment
in which web services live.  That's fine with me, but I'd like to make sure
that it is cleanly one way or the other.  And I think that once you allow
multiple responders you inevitably go down the slippery slope to the whole
orchestra enchilada. 

-----Original Message-----
From: Mark Baker [mailto:distobj@acm.org] 
Sent: Monday, February 25, 2002 9:50 AM
To: RogerCutler@chevrontexaco.com
Cc: steve.vinoski@iona.com; Mike.Champion@softwareag-usa.com;
www-ws-arch@w3.org
Subject: Re: Web Service Definition [Was "Some Thoughts ..."]


Roger,

> I like the way that this definition is going, too, but I think that as 
> it stands it is too broad because I think it will include 
> orchestrations and the sense of the group seemed to be that 
> orchestrations are a higher level construction than web services.  In 
> order to fix this I suggest that we define a web service as having the 
> following participants, all identified by
> URI's:
> 
> 1) A single "requestor".
> 
> 2) A single "responder".
> 
> 3) Zero or more "recipients".
> 
> A web service is initiated by a communication from the requestor to 
> the responder and the responder sends any number of communications to 
> the recipients.  All these commmunications are via web protocols.

I think you're too narrow now. 8-O  SOAP 1.2 explicitly supports an
extensible array of message exchange patterns[1].  Defining a web service in
these terms would unnecessarily restrict our scope, IMO.

For example, consider a voting service where I can ask a set of people to
vote for or against something.  In this case, there are multiple responders.

I'm not sure how what Steve or I suggested relates to orchestrations. I see
orchestrations (as I understand the term) to be Composites[2], that is, that
they are themselves Web services.

 [1] http://www.w3.org/TR/soap12-part2/#soaptmep
 [2] http://c2.com/cgi/wiki?CompositePattern

MB
-- 
Mark Baker, Chief Science Officer, Planetfred, Inc.
Ottawa, Ontario, CANADA.      mbaker@planetfred.com
http://www.markbaker.ca   http://www.planetfred.com
Received on Monday, 25 February 2002 10:58:36 GMT

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