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Re: issue: optional parts in <message>?

From: David Martin <martin@ai.sri.com>
Date: Wed, 08 May 2002 21:47:17 -0700
Message-ID: <3CD9FF55.B5C05642@ai.sri.com>
To: Sanjiva Weerawarana <sanjiva@watson.ibm.com>
CC: Jeffrey Schlimmer <jeffsch@windows.microsoft.com>, www-ws-desc@w3.org
Sanjiva Weerawarana wrote:

> "Jeffrey Schlimmer" <jeffsch@windows.microsoft.com> writes:
> > >
> > >On #2, I agree with many of the points made below. I think it is
> > helpful
> > >and clean to be able model at the abstract level  input /output to
> > >operations comprising 'n' distinct parts irrespective their fundamental
> > >type and nature.
> >
> > Reasoning about parts of a message without reasoning about their
> > representational type is an intriguing point, but I don't (yet) see how
> > this is used by bindings, development-time tools, or automatically
> > generated proxies that de/serialize.
> >
> > >IMO, XML Schema is too XML centric and using it model
> > >non-XML types is very unnatural.
> >
> > I see XML Schema as _the_ interoperable standard for representational
> > types, and it would be great if we could (someday) leverage it fully to
> > simplify WSDL.
>
> WSDL 1.1 uses XSD as an abstract type description language and not
> only a representational language. This is what all the use=literal,
> encoded stuff is about.
>
> We cannot drop that. If we do, we lose the ability to map a WSDL
> description to a non-XML binding.

I agree -- and, as I mentioned in a previous message, I can illustrate this
from our work on DAML-S.  That is, it made perfect sense to use DAML-S as the
abstract type description language in our WSDL declarations (instead of XSD).
(Our documents on this approach aren't quite ready yet, but once they are,
I'll inform this list.)

>
>
> > >Additionally you want to be able to just
> > >drop in existing Schemas (RosettaNet, OAG etc.) rather than having to
> > >define XML-Schema wrappers for them and any associated entities such as
> > >attachments etc.
> >
> > I don't buy this. I don't see how defining an XML Schema wrapper for
> > various entities is worse than defining a WSDL message wrapper for the
> > same.
>
> The point is that the "message" is what the user needs to define at
> that time. Another "type" is not the logical thing that the person is
> defining when they indicate that an operation takes a PO and a signature
> document say.

Right.  Again drawing on our recent DAML-S experience, there is a natural
mapping, from the inputs of a DAML-S process, to the parts of a WSDL message.
Certainly, for our use of WSDL, distinguishing these inputs, and mapping them
onto message parts, is logically distinct from defining their types.

Regards,
David Martin

>
>
> Syntactically, its not very different as Mike Deem carefully illustrated.
> I still believe that semantically its very different, so we're knowingly
> trading off some semantic clarity with syntactic convenience.
>
> Sanjiva.
Received on Thursday, 9 May 2002 00:45:37 GMT

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