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RE: Importing schemata into WSDL

From: Jacek Kopecky <jacek@systinet.com>
Date: 17 Oct 2002 17:19:02 +0200
To: Don Mullen <donmullen@tibco.com>
Cc: "'Sanjiva Weerawarana'" <sanjiva@watson.ibm.com>, WS Description WG <www-ws-desc@w3.org>
Message-Id: <1034867943.1795.219.camel@krava>

Don,

I disagree with points 1 and 3 from my experience of having implemented
(or cooperated on) a set of WSDL tools.

4 should not be a problem because published schemas should seldom or
never change; also many WSDL use unique namespaces so schema management
is mostly a schema replacement anyway. 8-)

6: well we want to say something about message parts. I think you have
nothing against importing external schemata, so really the analogy to
XSLT doesn't work because it isn't used in WSDL at all at the moment. So
I feel point 6 is pretty much void.

I agree completely with point 7. 8-)

XML syntax, especially namespaces, was explicitly designed for easy
vocabulary combinations, and this is directly against your point 8.

To conclude, I disagree with most of your points and I prefer we keep
the ability to embed schemata (because in some applications it really
simplifies distribution or processing) together with the ability to
refer to external schema documents.

Best regards,

                   Jacek Kopecky

                   Senior Architect, Systinet Corporation
                   http://www.systinet.com/



On Thu, 2002-10-17 at 16:50, Don Mullen wrote:
> 
> Sanjiva:
> 
> Some reasons not to include embedded schemas within WSDL files:
> 
> 1) Schema inclusion makes life difficult for tool builders.  Although the
> difficulties can be overcome, it is sometimes difficult to get interoperable
> results with tools that don't get this right.
> 
> 2) No identifiable location... some XML validators will be hard pressed to
> make use of the embedded schemas without having a physical location URI.
> XML instance documents cannot reference embedded schemas via schemaLocation.
> This could be dealt with using some sort of "inside of" or fragment URI
> convention, but again there isn't a clear interoperable way to do this.  
> 
> 3) Embedding a shared (or 3rd party) schema into several WSDLs, just for the
> simplicity aspect, can trip up systems that expect only one schema per
> namespace... now you have to pick one, or compare them, or something.
> 
> 4) Schema management across the organiziation becomes more difficult when
> you have schemas both in stand-alone documents and embedded within WSDLs.
> The embedded schemas would rarely be reused.
> 
> 5) In some sense (perhaps niave), it creates an expectation that WSDL
> defines types (is a schema language).
> 
> 6) If we are going to include schemas, why don't we also include XSLT
> operations, since it might be desirable to describe a transformation of the
> service request or result.  That is more obviously a silly idea.
> 
> 8) The only reason that these two were combined to begin with stems from
> both WSDL and XML Schema both being in XML syntax, and is convenient in
> simple stand-alone cases.  If, instead a non-XML metadata file was
> referenced, everyone would know from the get-go that the two needed to be in
> separate files.
> 
> Don
> 
> -----Original Message-----
> From: Sanjiva Weerawarana [mailto:sanjiva@watson.ibm.com]
> Sent: Friday, October 11, 2002 7:25 PM
> To: Don Mullen; 'Jacek Kopecky'; WS Description WG
> Cc: Amy Lewis
> Subject: Re: Importing schemata into WSDL
> 
> 
> "Don Mullen" <donmullen@tibco.com> writes:
> >
> > I would argue that WSDL 1.1 made a mistake in adding embedded schemas
> using
> > <types> -- WSDL should get out of types definitions space and drop <types>
> > completing -- just allow <import> of schemas.
> 
> I disagree - without the ability to inline schemas life becomes
> a pain. Why is it a mistake to allow one to inline schema
> documents??
> 
> WSDL is *not* in the type definitions space: It says to use
> XSD and allows one to place XSD definitions in the same XML document.
> That to me is just XML convenience, but obviously you have some
> other concern that I'm not grokking.
> 
> Sanjiva.
> 
Received on Thursday, 17 October 2002 11:19:08 GMT

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