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RE: Web Service Description and stateful services

From: Cutler, Roger (RogerCutler) <RogerCutler@chevrontexaco.com>
Date: Tue, 20 May 2003 06:41:22 -0500
Message-ID: <7FCB5A9F010AAE419A79A54B44F3718E01817E4A@bocnte2k3.boc.chevrontexaco.net>
To: "Sergio Andreozzi" <sergio.andreozzi@cnaf.infn.it>, www-ws-arch@w3.org

This strikes me as an EXTREMELY interesting question.

<disclaimer>Personal opinion follows -- I have no sense whatsoever
whether this would be the opinion of anyone else in the
group</disclaimer>

The WSDL document seems to me a strange place to put this sort of thing.
I would be interested in what motivated people to do so.  Is it that
there are tools available in the WSDL context that are useful for this
purpose?  Or is it because the nature of the information that specifies
this state is related to other information in the WSDL file?  Or
something else?

I think that this is a subject that we have not worked very much and
that we should do so.  Understanding why people are doing things this
way might be a good start.

Does this lead in the direction of thinking that there is a need outside
the scope of current activities that is sort of artificially being
crammed into this one?  If so, is another activity indicated?

-----Original Message-----
From: Sergio Andreozzi [mailto:sergio.andreozzi@cnaf.infn.it] 
Sent: Tuesday, May 20, 2003 6:03 AM
To: www-ws-arch@w3.org
Subject: Web Service Description and stateful services



Dear WS-ARCH group members,

the Web Services description is currently defined in the latest Web 
Service Architecture document (1.5.3) as:

"The service description is a machine processable specification of the 
message formats, datatypes and protocols that should be used between the

requester agent and the provider agent. It also specifies the network 
location of the provider agent, and may provide some information about 
the message exchange pattern that is expected"

In the research community, I've seen some attempt at representing the 
service state by using WSDL extensions, i.e. by extending the web 
service description with attributes that carry the information related 
to the current state of a service. This means that, for each service 
instance, a WSDL document should be created.

I would like to receive your point of view on the following issue. From 
the definition you give, I understand that the service state is a 
concept more related to the service representation (def. 2.2.29), while 
the service description (def. 2.2.32) should describe service interface 
and semantics.

Extending a WSDL document with service representation related data is 
somewhat merging service description with service representation. This 
solution might be handy when you want, for instance, advertise the 
quality related attributes in order to make a QoS based discovery.

 From a Web Service Architecture point of view, how do you deal with 
this issue and the above solution?

Any clarification is appreciated.

Thanks,

Sergio A.



-- 
Sergio Andreozzi

Istituto Nazionale di Fisica Nucleare - CNAF
Viale Berti Pichat, 6/2
40127 BOLOGNA
ITALY

E-mail : sergio.andreozzi@cnaf.infn.it
Website: www.cnaf.infn.it/~sergio
Received on Tuesday, 20 May 2003 07:42:23 GMT

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