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Re: Fw: Naming a Web service resource

From: Paul Denning <pauld@mitre.org>
Date: Mon, 07 Jul 2003 15:24:19 -0400
Message-Id: <5.2.0.9.0.20030707133323.03672eb8@mailsrv1.mitre.org>
To: www-ws-arch@w3.org

At 12:55 PM 2003-07-07, Francis McCabe wrote:

>Anne:
>   This topic has been discussed a little in WSA.

See
http://www.w3.org/2002/ws/arch/3/05/2003-05-15-ws-arch.htm

>I can give you my personal view on this; it is not one that is necessarily 
>shared ;-)
>
>1. The targetResource concept is, IMO, a brain-dead idea. The principal 
>reasons being:
>
>a. The resource that a service manipulates may not be identifiable in any 
>obvious way
>b. A service may be inherently `about' a dynamic set of resources, and 
>therefore it becomes onerous to identify them in the service description
>c. The action-oriented level of description implicit in a service 
>description is not the appropriate level to discuss resources.

I respectfully disagree with Frank's view.

"Resources" are abstractions anyway, not necessarily a physical 
resource.  I for one am not comfortable with the notion that a web service 
is not associated with a resource ( a view that has been discussed a 
little).  That would deviate too much from the TAG's web architecture, 
where a Resource is a fundamental concept.

The dynamic set of resources can be viewed as just another abstract 
resource, not necessarily a superset (or having sub-resources).
The targetResource for a choreography (transparently-composed composite 
service) is an abstraction (with perhaps some interesting relationships to 
other more or less abstract resources).

What is the resource for the URI http://www.w3.org?  for 
http://www.w3.org/TR?  They are abstractions.

I can see us having a discussion similar to
http://www.w3.org/2001/tag/ilist#namespaceDocument-8

That is, given only a targetResource URI, I will try to dereference it 
(like a namespace URI) to see if I can find out something more about 
it.  TAG is leaning toward RDDL as "an" acceptable namespace document 
(there may be others).  What is an acceptable "targetResource 
document"?  RDDL probably is also a good candidate.


>However, who am I to say what WSD gets up to?
>
>2. Web services *do* have identity; and hence can be expected to have a 
>URI. However, that does not imply that a Web service has a meaningful 
>representation:
>a. For a simple, atomic, service, one might assert that the binding 
>address of a service is a good candidate for the service identity. 
>However, that seems too low-level and too transport specific.
>b. The service description of a service is a potential candidate for the 
>service representation, but different descriptions of the same service are 
>likely.
>c. A composite service, in the sense of a transparently composed service, 
>is different to its component services and yet essentially unknown to the 
>component parts. A simple example: a service composing a weather service 
>with a language translation service to give weather reports in foreign 
>languages. Ideally, one should be able to build such a service with no 
>programming: simply by hooking together the weather service and the 
>translation service. The service description amounts to a particular 
>choreography over existing services. The foreign language weather service 
>is still a service, and still had an identity (it may be composed further, 
>by linking with an import-export service to predictively order umbrellas say).
>
>So, the upshot seems to be that a Web service has an identity, but that 
>that identity is closer in spirit to the namespace uri than a web page uri.

The namespace URI does not hack it for me.  I liked the idea of the 
targetResource.

For example, the public UDDI business Registry (UBR) could have a single 
targetResource URI whether you access the "resource" through IBM, MS, SAP, 
or NTT.  And it would differ from private UDDI registries, which would have 
a different targetResource URI.  Both UBR and private UDDI registries would 
use the same UDDI namespace and WSDL (interface, not implementation) 
description, i.e., 
http://www-3.ibm.com/services/uddi/uddiget?tModelKey=UUID:AC104DCC-D623-452F-88A7-F8ACD94D9B2B

I don't want to be forced to use OWL just to distinguish between UBR and a 
private UDDI registry.



>>>>Frank
>>>>
>>>>On Friday, July 4, 2003, at 07:10  AM, Anne Thomas Manes wrote:
<snip/>

Paul 
Received on Monday, 7 July 2003 15:24:26 GMT

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