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RE: What does WSDL describe?

From: <paul.downey@bt.com>
Date: Wed, 29 Oct 2003 09:58:32 -0000
Message-ID: <2B7789AAED12954AAD214AEAC13ACCEF0FFF1CE6@i2km02-ukbr.domain1.systemhost.net>
To: <Savas.Parastatidis@newcastle.ac.uk>, <www-ws-desc@w3.org>
Cc: <jimwebber@hotmail.com>, <distobj@acm.org>

Savas

AIUI the order form can implicitly contain data that results in radically different processing: 'buy motorcycle', 'update order' or 'cancel order' and the action taken may not be obvious from the GED or header fields. 

This effectively puts management as routing, access control and QOS out of the platform and into the domain of the thing that ultimately understands the message - the application. Also a change in the 'update order' part of the document has impact on every client, even those just interested in cancelling orders.

For me this issues boils down to a choice in service design and I don't think WSDL shouldn't enshrine or disallow either view: exposed methods or exchange of documents.

What I don't grasp is how 'messageExchanges' are essential to a SOA - i'd say reusable, coarse grained /operations/ are essential to a SOA, but i'll have to go away and think about that one now!

Paul

-----Original Message-----
From: Downey,PS,Paul,XSJ67A C 
Sent: 24 October 2003 12:06
To: 'Savas Parastatidis'; www-ws-desc@w3.org
Cc: Jim Webber; distobj@acm.org
Subject: RE: What does WSDL describe?


Savas

> I see from many messages in this and other discussion lists that many
people make the association between a WSDL "operation" and a method on
an object at the other end. Again, that's because the current tooling
out there has forced us to think of web services as objects with
methods, 

Forced is a bit strong. There are toolkits which use WSDL to generate code but there are other platforms which use documents as their native format. I think both models have equal merit and Web Services has proved to be an way of enabling these two universes to communicate.   

> We didn't send a document called "Buy a car" or "Buy a motorcycle". We
just sent a document called "OrderForm1". 

I guess in this example i'd choose an operation name of "SubmitOrder" or "BuyVehicle", and let the content (partNumber or whatever) provide the constriction, but maybe i'm missing the point - I'll re-read the post and think some more about this!

Paul

-- 
Paul Sumner Downey
Web Services Integration
BT Exact
Received on Wednesday, 29 October 2003 05:02:50 GMT

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