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RE: Web Service Description and stateful services - (on the 'www-ws@w3.org' list) Debating on a) Stateful Web Service Instances b) Stateful Interaction - OGSI

From: Ugo Corda <UCorda@SeeBeyond.com>
Date: Fri, 20 Jun 2003 19:50:38 -0700
Message-ID: <EDDE2977F3D216428E903370E3EBDDC908120A@MAIL01.stc.com>
To: "Assaf Arkin" <arkin@intalio.com>
Cc: "Christopher B Ferris" <chrisfer@us.ibm.com>, <www-ws-arch@w3.org>

> According to Chris's definition BPEL would fall in the stateless 
> interaction category.
> The process instance is the "maintained state". The service routes the 
> message to the proper instance by looking at the message contents (the 
> correlation). The correlation can identify the client (e.g. by including 
> it's endpoint), but typically it does not (e.g. using a PO number). 
> Clients and servers can come and go, the stateful interaction occurs 
> between stateful (state maintaining) processes.

That's not the way I read it. The process instance can very well be keeping track of previous requests from that particular client (e.g. by storing previous messages in internal variables) and be basing future actions on those previous requests. This would be equivalent in Chris' example to the case where "the server were implemented such that it *had* to remember which map the client had previously retrieved to make sense of the invocation to get more information about some coordinates on the map".

> If I am thinking in terms of the business service being offered then it 
> is stateful. The service being offered is the process, the process has a 
> maintained state and interaction with the process is often (not always, 
> but often enough) a stateful interaction. So the service for which WSDL 
> has a service definition is actually a stateful service.

That's exactly what I was referring to, i.e. the BPEL process offered as a Web service.

Received on Friday, 20 June 2003 22:50:52 UTC

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