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Re: pls review text added for what "required" means

From: David Booth <dbooth@w3.org>
Date: Wed, 28 Jul 2004 17:09:54 -0400
Message-Id: <>
To: "Sanjiva Weerawarana" <sanjiva@watson.ibm.com>, <www-ws-desc@w3.org>


Actually, since the processor conformance section only pertains to the 
requester  agent rather than the provider agent, and this material pertains 
to the provider agent, I think it may make more sense to put it in section 
6 (Language Extensibility).

In section 6, I suggest modifying the first sentence of the opening 
paragraph as follows:
In addition to extensibility implied by the Feature and Property components 
described above, the schema for WSDL has a two-part extensibility model 
based on namespace-qualified elements and attributes.

Then in section 6.1.1 (Mandatory extensions) I suggest changing the second 
paragraph to:
An extension that is NOT marked as mandatory MUST NOT invalidate the 
meaning of any part of the WSDL document. Thus, a NON-mandatory extension 
merely provides additional description of capabilities of the 
service.   This specification does not provide a mechanism to mark 
extension attributes as being required.  Thereore, all extension attributes 
are NON-mandatory.
(The sentence about "Furthermore, any extension that is NOT marked as 
mandatory and which is NOT understood, MUST be ignored" was unnecessary 
here, as that is covered in section 8 Conformance .)

Then after the Note, add:
If a WSDL document declares an extension, Feature or Property as optional 
(i.e., NON-mandatory), then the provider agent MUST NOT assume that the 
requester agent supports that extension, Feature or Property, _unless_ the 
provider agent knows (through some other means) that the requester agent 
has in fact elected to engage and support that extension, Feature or 

On the other hand, a requester agent MAY engage an extension, Feature or 
Property that is declared as optional in the WSDL document.  Therefore, the 
provider agent MUST support every extension, Feature or Property that is 
declared as optional in the WSDL document, in addition to supporting every 
extension, Feature or Property that is declared as mandatory.

If finer-grain, direction-sensitive control of extensions, Features or 
Properties is desired, then such extensions, Features or Properties may be 
designed in a direction-sensitive manner (from requester or from provider) 
so that either direction may be separately marked required or 
optional.  For example, instead of defining a single extension that governs 
both directions, two extensions could be defined -- one for each direction.

At 02:58 AM 7/27/2004 +0600, Sanjiva Weerawarana wrote:

>In fullfilling the following editorial action item:
> > ?ED       2004-06-17: Editors to incorporate David Booth's clarification
> >                       in section 8.3 about what required means on MTOM
> >                       feature.
>I put the following into section 8.3 (of part1):
>           <note><p>If a WSDL document declares an extension or feature
>           as optional, then if that extension or feature could apply
>           to messages sent by the provider agent as well, then the
>           provider agent MUST NOT send any messages that requires the
>           requester agent to support that extension or feature. The
>           requestor, on the othe hand, MAY engage that extension or
>           feature in messages it sends to the provider.</p>
>           <p>If finer-grain control of extensions and features is
>           desired then such extensions and features must be designed
>           in a direction (from requestor or from provider) sensitive
>           manner so that any direction may be marked required or
>           optional.</p></note>
>I didn't make that MTOM specific because that doesn't make sense in
>part1 IMO.
>Comments please.

David Booth
W3C Fellow / Hewlett-Packard
Telephone: +1.617.253.1273
Received on Wednesday, 28 July 2004 17:09:57 UTC

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