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RE: Importing schemata into WSDL

From: Don Mullen <donmullen@tibco.com>
Date: Thu, 17 Oct 2002 10:50:46 -0400
Message-ID: <339902DC0E58D411986A00B0D03D843201B24673@extmail.rtp.tibco.com>
To: "'Sanjiva Weerawarana'" <sanjiva@watson.ibm.com>, WS Description WG <www-ws-desc@w3.org>


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.


-----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
> <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

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.

Received on Thursday, 17 October 2002 10:52:43 UTC

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