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Re: Message Reference, Message|element encore

From: FABLET Youenn <youenn.fablet@crf.canon.fr>
Date: Thu, 19 Feb 2004 11:22:38 +0100
Message-ID: <40348E6E.7000901@crf.canon.fr>
To: Bijan Parsia <bparsia@isr.umd.edu>
Cc: www-ws-desc@w3.org

As suggested by Bijan, there are many HTTP messages exchanged on the web 
that have simple types data in them, for instace text/plain messages. 
This leads to some questions:
    1) Do we want to allow WSDL to describe non-xml message exchanges?
    2) If yes, do we want to support the description of non-xml message 
exchanges within the HTTP binding?
If so, there might be a need to retrieve from a WSDL description the 
mime type of a particular wsdl message, either at the abstract or 
concrete level. WSDL cannot describe non-xml HTTP exchanges with the 
current HTTP binding because the content-type of HTTP requests and 
responses is currently specified statically in the HTTP binding spec.

Bijan Parsia wrote:

> So, mulling over section 2.4  
> (http://dev.w3.org/cvsweb/~checkout~/2002/ws/desc/wsdl20/ 
> wsdl20.html#MessageReference) yet again:
> 1) At the F2F, did we agree to change the name of the component  
> property {message} to "element", or only the attribute?
> 2) At the F2F, Roberto (I believe) assuaged my worries by pointing to  
> the mapping in 2.4.3:
>     """{message}     The element declaration resolved to by the value 
> of the  message attribute information item if present, otherwise a 
> similar  construct in some type system as referred to by some other 
> attribute  information item if present, otherwise empty."""
>     This suggests that the {message} *component* can refer to types 
> in  arbitrary type systems. However:
>     a) The text in 2.4.1 reads:
>     """ {message} A reference to an XML element declaration. This 
> element  represents the content or "payload" of     the message"""
>     Which pretty much *states* that the value of a {message} 
> component  property is an element declaration     *only*. This seems 
> to be a tension  in the text.
>     b) I don't see any way to tell *which* type system the {message}  
> component property refers too
> 3) In section 3.1.3:
>  """A named, global xs:element declaration may be referenced from the  
> message attribute information item of an input or output element  
> information item. The QName is constructed from the targetNamespace 
> of  the schema and the content of the name attribute information item 
> of  the xs:element element information item. A message attribute  
> information item may not refer to an xs:simpleType or an 
> xs:complexType  element information item."""
> I don't understand why there is a restriction against referencing  
> xs:simpleTypes. It seems to me that there are plenty of messages 
> (HTTP  reponses with text/plain bodies?) that are properly described 
> by  xs:simpleTypes (maybe UPnP as well?) If at all possible, I'd like 
> to  see the restriction removed.
> All this suggests (to me) that having to add an attribute for each 
> type  system is, well, annoying :) Why not have a pair of component  
> properties, {typeSystem} and {type}. And better, let there be two  
> attributes in the XML as well. For XML Schema element declarations, 
> we  can make that omitting the type system attribute defaulst to XML 
> Schema  element declarations.
> Cheers,
> Bijan Parsia.
Received on Thursday, 19 February 2004 05:23:09 UTC

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