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RE: Examples of substitution group extending WSDL.

From: David Orchard <dorchard@bea.com>
Date: Fri, 11 Jul 2003 13:04:49 -0700
To: "'Jonathan Marsh'" <jmarsh@microsoft.com>, "'Dale Moberg'" <dmoberg@cyclonecommerce.com>, "'Roberto Chinnici'" <Roberto.Chinnici@Sun.COM>
Cc: <www-ws-desc@w3.org>
Message-ID: <035001c347e7$afbafab0$fefb000a@beasys.com>
Seems like the various solutions, wildcards/substitution groups, are having
difficulties because of the design of XML Schema.

I think that what you want to be able to say is "in schema foo(wsdl) with
bar type(definitions) that is extensible, bar containing a baz
extension(dsig) type must be validatable".  If I understand correctly,
wildcards are limited in the ability for extensions to be validated, which
can be solved in substitution groups.

Is this similar to "in schema foo(soap) with a bar type(header) that is
extensible, bar must contain baz extension element(ws-security)"?  

It seems to me that a good chunk of WSDL designed to overcome the XML Schema
inability to deal with specifying schemas for extensions for message
content, and the same problem is cropping up in specifying validation of
extensions in wsdl schema itself.

Is there a consistent architectural problem that is being observed?

Dave

> -----Original Message-----
> From: www-ws-desc-request@w3.org [mailto:www-ws-desc-request@w3.org]On
> Behalf Of Jonathan Marsh
> Sent: Tuesday, July 01, 2003 3:24 PM
> To: Dale Moberg; Roberto Chinnici
> Cc: www-ws-desc@w3.org
> Subject: RE: Examples of substitution group extending WSDL.
> 
> 
> 
> A wrapper, while largely aesthetic, represents specific 
> knowledge of how
> WSDL and the extension work together.  In general I prefer to allow
> direct embedding to avoid a combinatorial explosion of special-case
> interactions between vocabularies.  If I have a process that takes XML
> and inserts a digital signature, why should that process have to treat
> WSDL as a special case?
> 
> It is aesthetically offensive to add a wrapper if it's only 
> an artifact
> of the schema language we're considering.  It limits the power of the
> language (in this case XML) to fit the failings of the description (in
> this case schema) language.
> 
> > -----Original Message-----
> > From: Dale Moberg [mailto:dmoberg@cyclonecommerce.com]
> > Sent: Friday, June 27, 2003 6:20 AM
> > To: Roberto Chinnici; Jonathan Marsh
> > Cc: www-ws-desc@w3.org
> > Subject: RE: Examples of substitution group extending WSDL.
> > 
> > 
> > 
> >  Roberto Chinnici wrote
> > >Jonathan Marsh wrote:
> > >> Results of my tinkering
> > 
> > >> Then I attempted the holy grail, a simple wrapper schema 
> that would
> > >> have the effect of the schema above, while importing the DSig
> schema
> > >> without modification.  I failed in this because:
> > >> - Element declarations in an imported schema cannot be 
> overridden.
> > >> - Redefine does not work on element declarations.
> > >> - There is no other way to add elements to a substitution group.
> > 
> > >This is bad news.
> > 
> > >> I rejected modifications to the instance document that 
> would enable
> a
> > 
> > >> wrapper schema:
> > >> - Changing the namespace of the top level element.
> > >> - Introducing a wrapper element.
> > >
> > >Given the issue with xsi:schemaLocation described earlier, 
> I find the
> > >wrapper solution more acceptable than the one above, no matter how
> > >unaesthetical and inconvenient.
> > 
> > I also don't sense that there is a lot of inconvenience in using a
> > "wrapper" element;
> > I would expect to find new tags for elements that are 
> introduced with
> > reference
> > to a substitution group head element. {Maybe I have low expectations
> > when it comes to
> >  using schema tips and tricks, though.)
> > 
> > And, my aesthetic sense favors having these new wrapper element in a
> > distinct namespace
> > (in terms of the example, neither in wsdl12 or DSIG namespace) that
> > packages up the extension(s).
> > Is there something other than aesthetics or a Ockhamistic fetish
> > at work in disparaging the lowly wrapper element?
> > Are we going to start littering the schema with "any*" constructs
> > instead?
> 
> 
> 


Received on Friday, 11 July 2003 16:05:27 GMT

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