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Re: Definition for a Web Service

From: Francis McCabe <fgm@fla.fujitsu.com>
Date: Mon, 11 Aug 2003 12:58:47 -0700
Cc: "Cutler, Roger \(RogerCutler\)" <RogerCutler@chevrontexaco.com>, "Jean-Jacques Moreau" <jean-jacques.moreau@crf.canon.fr>, <www-ws-arch@w3.org>
To: "Anne Thomas Manes" <anne@manes.net>
Message-Id: <388A474C-CC36-11D7-8496-000393A3327C@fla.fujitsu.com>


However, I don't think the omission was deliberate.

There are some issues with associating a URI with a service:

	IMO the primary purpose of a Web service URI is for *inference* -- we 
can use the same identifier in two different places/times in order to 
*assert* that the service being used is the same service.
    This is different to the Web service's endpoint information, and it 
is also different to the targetResource.

    Where is can probably *not* be used is in any messages to/from the 
service!!!! Or at least, not without considerable consequences:
a. If a message to a service mentions the Service URI, and the agent is 
expecting a different URI what gives? In any case, presumably, a 
Service agent already knows its URI and doesn't need telling.
b. In a composite service, where a reply may come from a different 
agent than the requested agent, none of the entities may be aware of 
the service URI


On Monday, August 11, 2003, at 11:02  AM, Anne Thomas Manes wrote:

> I raised a discussion on the WS-Desc list suggesting that they really 
> should
> identify a Web service by a URI rather than just a Qname. I was a 
> little
> surprised by the resistence to such a concept. I got the sense that a 
> lot of
> people didn't understand what in fact the URI was meant to identify.
> I don't know what the end decision on the discussion was. I believe it 
> was
> discussed at the last meeting.
> But I do think that the architecture group should have some influence 
> on the
> discussion. If the architecture group believes that a Web service 
> should be
> named by a URI, then the WS-Desc team should provide a means to 
> capture that
> name in the WSDL description.
> From my perspective, a Web service is an "important" resource, and as 
> the
> Web Architecture says, all "important" resources should have a URI. I 
> also
> expect that a Web service may be described by a variety of description
> languages (WSDL, DAML, text documents, etc.) and so there ought to be a
> means of referring to the Web service that doesn't depend on just one
> description language (a URI derived from the wsdl:service Qname).
> Anne
> ----- Original Message -----
> From: "Cutler, Roger (RogerCutler)" <RogerCutler@chevrontexaco.com>
> To: "Jean-Jacques Moreau" <jean-jacques.moreau@crf.canon.fr>;
> <www-ws-arch@w3.org>
> Sent: Monday, August 11, 2003 10:47 AM
> Subject: RE: Definition for a Web Service
>> I think that this happened because of all the confusion about URI's 
>> and
>> QNames.  As I understand it (and I am very willing to admit that I
>> understand this imperfectly), just about everyone concerned would be
>> VERY happy to say that Web services are identified by URI's -- except
>> that currently in WSDL they are identified by a Qname -- which is not
>> exactly a URI but can be mapped to a URI.  This, at the least, adds a
>> layer of confusion to any conversation on this subject.  I think that
>> the basic thinking was that the "Web-related standards" would lead one
>> sort of inevitably to URI's, and that the detailed issues could be 
>> dealt
>> with ... in the detailed sections, I guess.
>> -----Original Message-----
>> From: Jean-Jacques Moreau [mailto:jean-jacques.moreau@crf.canon.fr]
>> Sent: Monday, August 11, 2003 3:45 AM
>> To: www-ws-arch@w3.org
>> Subject: Definition for a Web Service
>> Thanks for the new draft; obviously, this is the result of a lot of
>> efforts!
>> Regarding the new definition for a Web Service: apart from being more
>> specific (WSDL, SOAP, HTTP), which I like, the other major difference
>> seems to be that a Web Service is no longer identified by a URI. Is 
>> this
>> intentional? Shouldn't this be added back?
>> <previousDefinition>
>> A Web service is a software system identified by a URI [...].
>> </previousDefinition>
>> Comments?
>> Jean-Jacques.
>> Champion, Mike wrote:
>>> Update from the W3C publication team:
>>> New WD of "Web Services Architecture" Document is available at :
>>> http://www.w3.org/TR/2003/WD-ws-arch-20030808/
Received on Monday, 11 August 2003 15:59:02 UTC

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