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RE: What WSDL defines - the diagram!

From: David Booth <dbooth@w3.org>
Date: Mon, 10 Nov 2003 17:19:36 -0500
Message-Id: <5.1.0.14.2.20031110164532.02e844a0@localhost>
To: "Savas Parastatidis" <Savas.Parastatidis@newcastle.ac.uk>
Cc: <www-ws-desc@w3.org>, "Anne Thomas Manes" <anne@manes.net>

Savas,

Your modified diagram[1] differs from mine[2] in three ways.  I agree with 
2 out of 3 of your changes:

1. AGREED: Your diagram indicates that a WSDL document "Defines *syntactic* 
conformance" of a message.  Yes, that was what I meant.  (Some may argue 
XML Schema allows you to constrain slightly more than syntax, but I don't 
think there's any point in nit picking about that.)

2. AGREED: Your diagram indicates that a WSDL document defines "MEPs and 
protocols" of a service, whereas my diagram said it (partially) defines 
"behavior" of the service.  Yes, that was what I meant.

3. DISAGREED: Your diagram seems to indicate that a WSDL document does NOT 
define the behavior of the client, and I disagree with this.  A WSDL 
document certainly DOES (partially) define the behavior of the client, in 
the same way that it (partially) defines the behavior of the 
service.  That's what MEPs are all about.  An MEP constrains the behavior 
of BOTH parties.  If the client violates what the MEP requires, then that 
client is not behaving in accordance with the WSDL document.  The same is 
true of the service.

A WSDL document inherently represents an agreement (or "contract") between 
*two* parties: an (unnamed) client and the service.  It is written from the 
perspective of the service, but it constrains both.

References
1. http://lists.w3.org/Archives/Public/www-ws-desc/2003Nov/0034.html
2. http://lists.w3.org/Archives/Public/www-archive/2003Nov/0002.html

At 07:42 PM 11/4/2003 +0000, Savas Parastatidis wrote:
>My +1 to Anne's +1 comes with annotations to the original diagram :-)
>(Apologies to Paul for the modifications to his diagram)
>
> > -----Original Message-----
> > From: Anne Thomas Manes [mailto:anne@manes.net]
> > Sent: Tuesday, November 04, 2003 6:34 PM
> > To: Mark Baker; paul.downey@bt.com
> > Cc: www-ws-desc@w3.org
> > Subject: Re: What WSDL defines - the diagram!
> >
> >
> > +1.
> >
> > WSDL explicitly does not define client or service behaviour. It
>describes
> > syntax of messages and protocols used to exchange those messages.
> >
> > Anne
> >
> > At 10:41 AM 11/4/2003, Mark Baker wrote:
> >
> > >Cool, thanks for tackling that at the f2f.
> > >
> > >But I disagree with the diagram.  As it was explained to me, a WSDL
>2.0
> > >document could be said to "describe the syntax" of client and service
> > >("schema in, schema out"), rather than "define the behaviour", which
> > >would require defining what in/out means in relation to any requested
> > >semantics (aka the protocol).
> > >
> > >WSDL 1.1 describes the protocol in that it suggests that a successful
> > >response to a message means that the requested operation in the
>message
> > >was successfully invoked.  WSDL 2.0 is ambiguous.
> > >
> > >Mark.
> > >--
> > >Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
> >
>
>

-- 
David Booth
W3C Fellow / Hewlett-Packard
Telephone: +1.617.253.1273
Received on Monday, 10 November 2003 17:19:48 GMT

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