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Re: Can one inline schema import definitions from a second inline schema?

From: Arthur Ryman <ryman@ca.ibm.com>
Date: Fri, 17 Oct 2003 14:18:45 -0400
To: www-ws-desc@w3.org
Message-ID: <OF7E05C7C8.ABEA8900-ON85256DC2.00636661@ca.ibm.com>
The consensus seems to be that multiple <schema> elements are OK. The 
schemaLocation attribute is not required and is in any case only a hint 
where to find the schema. I therefore suggest that we include this example 
of two mutually referiing inline <schema> elements in the Primer to clear 
up any potential misunderstanding.

Although this interpretation seems to be a consequence of the WSDL and XSD 
specs, it is not "obvious" to at least some of us...

It's worth recalling the story of the very famous mathematician, G.H. 
Hardy, who in a lecture said about some detail in a proof: "This is 
obvious." After a pause, he went on: "Hmm, is it really obvious?" After 
another pause he left the room to consider the point, returning 20 minutes 
later with the verdict: "Yes, I was right, it is obvious."

Arthur Ryman




"Amelia A. Lewis" <alewis@tibco.com>
Sent by: www-ws-desc-request@w3.org
10/17/2003 12:03 PM

 
        To:     paul.downey@bt.com
        cc:     mgudgin@microsoft.com, sanjiva@watson.ibm.com, Arthur 
Ryman/Toronto/IBM@IBMCA, Lawrence Mandel/Toronto/IBM@IBMCA, 
www-ws-desc@w3.org, www-ws-desc-request@w3.org
        Subject:        Re: Can one inline schema import definitions from a second inline  schema?




Do we need to do so?

The current language of the specification seems fairly straightforward. 
We permit, as immediate children of types, when W3C XML Schema is used
(and it is the only schema language required to be supported by all WSDL
processors), both xs:schema and xs:import.  We *do not* constrain the
semantics of these child elements, except to change @targetNamespace to
REQUIRED (for embedded and imported schemata both).

We should not, in my opinion, overconstrain W3C XML Schema.  We have
already forbidden the use of chameleon schemata, which removes an
enormous burden on processors; support for that [mis?]feature would have
placed an unacceptable burden on the WSDL processor, since we would have
had to define the semantics of chameleon schemata in a context never
anticipated (the idea that a WSDL targetNamespace could apply to an
imported/embedded schema makes for all sorts of really interesting and
sometimes quite surprising interactions).

In so far as is possible, we should *not* change semantics of W3C XML
Schema, in my opinion.  The value of requiring it as a supported schema
language lies in the re-use of existing schema processors.  If we begin
to place further constraints upon it, it stops being the language
supported by existing processors, and requires a whole new generation of
processors customized for schema-in-WSDL-context.

The idea behind embedding and importing schema, as I understand it, is
to rule that whole complex area *out of scope* for the WSD WG.  Writing
a schema language is *hard*, we need to reuse, not reinvent, and not
revise.  This allows us to focus on what we [should?] do best.

Amy!
On Fri, 17 Oct 2003 16:39:32 +0100
paul.downey@bt.com wrote:

> 
> isn't this an issue about how multiple inline schemas reference each
> other in a   single WSDL document ?
> 
> AIUI it's just a matter of formally stating what appears to be a
> common practice.
> 
> Paul
> 
> -----Original Message-----
> From: Martin Gudgin [mailto:mgudgin@microsoft.com]
> Sent: 17 October 2003 16:36
> To: Downey,PS,Paul,XSJ67A C; sanjiva@watson.ibm.com; ryman@ca.ibm.com
> Cc: lmandel@ca.ibm.com; www-ws-desc@w3.org; www-ws-desc-request@w3.org
> Subject: RE: Can one inline schema import definitions from a second
> inline schema?
> 
> 
> Given that xs:import is defined by XML Schema and NOT WSDL, I don't
> see how WSDL can really constrain it in any way.
> 
> Gudge
> 
> > -----Original Message-----
> > From: paul.downey@bt.com [mailto:paul.downey@bt.com] 
> > Sent: 17 October 2003 16:35
> > To: sanjiva@watson.ibm.com; Martin Gudgin; ryman@ca.ibm.com
> > Cc: lmandel@ca.ibm.com; www-ws-desc@w3.org;
> > www-ws-desc-request@w3.org Subject: RE: Can one inline schema import
> > definitions from a second inline schema?
> > 
> > i don't think the BP doesn't preclude more than 1 schema 
> > within the types section - though i couldn't see anything 
> > about referencing between inline schemas.
> > 
> > FWIW, quite a few existing kits (including .NET) will 
> > generate WSDL 1.1 with multiple inline schemas which 
> > reference each other using <import namespace="blah"> - with a 
> > missing schemaLocation ..
> > 
> > maybe the anonymous schemaLocation should be 
> > supported/precluded explicitly in WSDL 1.2 ?
> > 
> > 
> > --
> > Paul Sumner Downey
> > Web Services Integration
> > BT Exact
> > 
> > 
> > 
> > 
> > -----Original Message-----
> > From: Sanjiva Weerawarana [mailto:sanjiva@watson.ibm.com]
> > Sent: 17 October 2003 16:02
> > To: Martin Gudgin; Arthur Ryman
> > Cc: Lawrence Mandel; www-ws-desc@w3.org; www-ws-desc-request@w3.org
> > Subject: Re: Can one inline schema import definitions from a second
> > inline schema?
> > 
> > 
> > 
> > Didn't we discuss this a while back and say only *1* schema within
> > <types>?? Or maybe that WSI BP that does that?
> > 
> > Sanjiva.
> > 
> > ----- Original Message -----
> > From: "Arthur Ryman" <ryman@ca.ibm.com>
> > To: "Martin Gudgin" <mgudgin@microsoft.com>
> > Cc: "Lawrence Mandel" <lmandel@ca.ibm.com>; <www-ws-desc@w3.org>;
> > <www-ws-desc-request@w3.org>
> > Sent: Friday, October 17, 2003 7:56 PM
> > Subject: RE: Can one inline schema import definitions from a 
> > second inline
> > schema?
> > 
> > 
> > > Gudge,
> > >
> > > I agree to some extent, but AFAIK, WSDL is the only application
> > > that inlines <schema>. I think the XSD spec assumes you have a 
> > single <schema>
> > > per document, i.e. <schema> is the root element. So 
> > processing not one,
> > > but two or more inline schemas is a bit of a shock for your 
> > typical XSD
> > > processor. So probably the "reasonable" behavior you describe is
> > > undefined.
> > >
> > > I think it would promote interoperability if the WSDL 1.2 
> > was clear on
> > > this point, one way or the other. From your response, I 
> > assume you would
> > > support the use of more than one inline <schema> in the 
> > <types> element.
> > >
> > > Arthur Ryman
> > >
> > >
> > >
> > >
> > > "Martin Gudgin" <mgudgin@microsoft.com>
> > > Sent by: www-ws-desc-request@w3.org
> > > 10/17/2003 06:17 AM
> > >
> > >
> > >         To:     Lawrence Mandel/Toronto/IBM@IBMCA, 
> > <www-ws-desc@w3.org>
> > >         cc:
> > >         Subject:        RE: Can one inline schema import 
> > definitions from
> > a second inline schema?
> > >
> > >
> > >
> > >
> > > To be frank, I think this has very little to do with WSDL. It is
> > > perfectly coherent for a schema processor, on encountering 
> > <xsd:import
> > > namespace='http://namespace1' /> to say to itself, ah, I 
> > have a schema
> > > for that namespace, I'll use that here. Likewise, when it
> > > encounters<xsd:import namespace='http://namespace2' /> it would
> > > say, 
> > ah, not seen
> > > that namespace yet, I'll wait and see what happens.
> > >
> > > Gudge
> > >
> > > > -----Original Message-----
> > > > From: www-ws-desc-request@w3.org
> > > > [mailto:www-ws-desc-request@w3.org] On Behalf Of Lawrence Mandel
> > > > Sent: 16 October 2003 23:19
> > > > To: www-ws-desc@w3.org
> > > > Subject: Can one inline schema import definitions from a
> > > > second inline schema?
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Hello,
> > > >
> > > > We have customers that do the following in WSDL 1.1:
> > > >
> > > > <types>
> > > >  <schema targetNamespace="http://namespace1" xmlns=
> > > > "http://www.w3.org/2001/XMLSchema"
> > > > xmlns:two="http://namespace2">
> > > >    <import namespace="http://namespace2"/>
> > > >    <complexType name="myComplexType">
> > > >     <sequence>
> > > >      <element name="myElement" type="two:B"/>
> > > >     </sequence>
> > > >    </complexType>
> > > >    <complexType name="A">
> > > >     <sequence>
> > > >      <element name="elementA" type="xsd:string"/>
> > > >     </sequence>
> > > >    </complexType>
> > > >   </schema>
> > > >   <schema targetNamespace="http://namespace2" xmlns=
> > > > "http://www.w3.org/2001/XMLSchema"
> > > > xmlns:one="http://namespace1">
> > > >    <import namespace="http://namespace1"/>
> > > >    <complexType name="myComplexType">
> > > >     <sequence>
> > > >      <element name="myElement" type="one:A"/>
> > > >     </sequence>
> > > >    </complexType>
> > > >    <complexType name="B">
> > > >     <sequence>
> > > >      <element name="elementB" type="xsd:string"/>
> > > >     </sequence>
> > > >    </complexType>
> > > >   </schema>
> > > > </types>
> > > >
> > > > The customers say that this is not explicitly forbidden by
> > > > the WSDL 1.1 specification and I can't find anything that
> > > > forbids this in the WSDL 1.1 specification.  However, there
> > > > is nothing in the WSDL 1.1 specification that states how to
> > > > import a schema defined in the same types section but with a
> > > > different namespace.
> > > >
> > > > Is this allowed according to the WSDL 1.2 specification?  If
> > > > so, what is the correct way to import one inline schema 
> > into another?
> > > >
> > > > Thanks,
> > > >
> > > > Lawrence Mandel
> > > >
> > > > Software Developer
> > > > WebSphere Studio Application Developer - XML Tools
> > > > Phone: 905 - 413 - 3814   Fax: 905 - 413 - 4920
> > > > lmandel@ca.ibm.com
> > > >
> > > >
> > > >
> > >
> > >
> > >
> > >
> > 
> > 
> > 
> 
> 


-- 
Amelia A. Lewis
Architect, TIBCO/Extensibility, Inc.
alewis@tibco.com
Received on Friday, 17 October 2003 14:18:55 GMT

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