W3C home > Mailing lists > Public > www-ws-desc@w3.org > October 2003

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

From: Amelia A. Lewis <alewis@tibco.com>
Date: Wed, 22 Oct 2003 15:01:37 -0400
To: Jonathan Marsh <jmarsh@microsoft.com>
Cc: www-ws-desc@w3.org
Message-id: <20031022150137.674499f2.alewis@tibco.com>

But as Paul Downey pointed out in response to my reference to schema's
constraints, schema *itself* forbids importing a schema from any
document whose root is not <schema>.  Strictly speaking, that includes
wsdl:definitions.  The only way around that would be to special-case it
*in the WSDL specification*, to basically say that the embedded schemas
MAY be treated as roots of separate documents.

Amy!
On Wed, 22 Oct 2003 11:54:12 -0700
Jonathan Marsh <jmarsh@microsoft.com> wrote:

> I've raised a question on the intent of R2004 in the BP - I had
> assumed it was focused on ensuring the right version of Schema was
> used, and it may be that disallowing imports between multiple inline
> schemas is an unintended side-effect of the language.
> 
>  
> 
> ________________________________
> 
> From: www-ws-desc-request@w3.org [mailto:www-ws-desc-request@w3.org]
> On Behalf Of Anne Thomas Manes
> Sent: Saturday, October 18, 2003 5:46 AM
> To: Martin Gudgin; www-ws-desc@w3.org
> Subject: RE: Can one inline schema import definitions from a second
> inline schema?
> 
>  
> 
> Regarding xs:import location pointing to a file with <schema> root
> element:
> 
> I don't believe that the schema spec requires that, but the WS-I BP
> does. R2004:
> 
> 
> 5.1.2 WSDL and Schema Import
> 
> 
> Some examples in WSDL 1.1 incorrectly show the WSDL import statement
> being used to import XML Schema definitions. The Profile clarifies use
> of the import mechanisms to keep them consistent and confined to their
> respective domains. Imported schema documents are also constrained by
> XML version and encoding requirements consistent to those of the
> importing WSDL documents. 
> 
> R2001 A DESCRIPTION MUST only use the WSDL "import" statement to
> import another WSDL description. 
> 
> R2002 To import XML Schema Definitions, a DESCRIPTION MUST use the XML
> Schema "import" statement. 
> 
> R2003 A DESCRIPTION MUST use the XML Schema "import" statement only
> within the xsd:schema element of the types section. 
> 
> R2004 A DESCRIPTION MUST NOT use the XML Schema "import" statement to
> import a Schema from any document whose root element is not "schema"
> from the namespace "http://www.w3.org/2001/XMLSchema". 
> 
> Anne
> 
> At 06:10 AM 10/18/2003, you wrote:
> 
> 
> 
> 
>  
> 
> > -----Original Message-----
> > From: Lawrence Mandel [mailto:lmandel@ca.ibm.com] 
> > Sent: 17 October 2003 19:08
> > To: Amelia A. Lewis
> > Cc: Arthur Ryman; Martin Gudgin; paul.downey@bt.com; 
> > sanjiva@watson.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 agree that using the schema language as intended is the best
> > option. However, the xs:import element was not designed with the
> > idea of importing a schema that is located in the same physical 
> > file as the schema that is importing it. Existing schema 
> > processors do not know how to resolve inline schemas by 
> > default and will have to be configured to do so. 
> 
> Why? If I were a WSDL processor, I'd just load up my favorite schema
> processor and pass it the two schema elements.
> 
> 
> > Not 
> > clarifying the correct way to import an inline schema will 
> > result in different takes on how to import an inline schema. 
> 
> XML Schema already deals with this by allowing xs:import with no
> schemaLocation.
> 
> > This is a potential interoperability problem that can be 
> > addressed at the WSDL specification level (rather then 
> > leaving this for the WS-I Basic Profile). If this is not 
> > clarified, what will it mean if someone has an import 
> > statement such as
> > 
> > <xs:import namespace="http://mynamespace" 
> > schemaLocation="mywsdl.wsdl"/>
> 
> I seem to remember the schema spec saying something about a
> schemaLocation resolving to something with <xs:schema> as its
> top-level element. Anyone else have a similar recollection?
> 
> > 
> > Will that resolve http://mynamespace <http://mynamespace/>  to
> > another
> inline 
> > schema? Will the following be valid?
> > 
> > <xs:import namespace="http://mynamespace"
> > schemaLocation="http://mynamespace <http://mynamespace/> "/>
> 
> A schema processor is at liberty to ignore schemaLocation on import,
> so this could resolve locally.
> 
> > 
> > Or is the correct way
> > 
> > <xs:import namespace="http://mynamespace <http://mynamespace/> "/>
> 
> All the above are legal. Only the latter would resolve to 'a schema
> the schema processor got by some unknown mechanism' ( i.e. another
> inline schema )
> 
> > 
> > I tend to think that not including a schemaLocation is the 
> > correct way but there is currently nothing that will prevent 
> > others from using one of the other two import statements.  
> > Because WSDL is using XML Schema in a way that it was not 
> > intended to be used 
> 
> Who says? I think this was absolutely one of the ways schema was
> intended to be used.
> 
> > the WSDL specification should make 
> > clarifications to XML Schema where needed.
> > 
> > Alternatively, if the goal is to use XML Schema as it was 
> > designed, 
> 
> XML Schema was designed to allow a schema processor to construct a
> schema in any way it saw fit. External documents, element nodes from a
> DOM etc.
> 
> > inline schemas should not be allowed at all and all 
> > schemas should be defined in external documents and imported 
> > into WSDL documents. This approach will maintain the 
> > independence and integrity of XML Schema and reduce the 
> > amount of clarifications the WSDL specification needs to make 
> > as a result of using XML Schema internally in WSDL documents.
> 
> I'm still not convinced any such clarification is necessary
> 
> Gudge
> 
> > 
> > Comments?
> > 
> > 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"                                
> >              
> >              <alewis@tibco.com                                
> >              
> >              >                                                
> >           To 
> >                                        paul.downey@bt.com     
> >              
> >              10/17/2003 12:03                                 
> >           cc 
> >              PM                        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
> <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 <http://namespace2/> ">
> > > > > >    <import namespace="http://namespace2 <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
> <http://namespace2/> " xmlns= 
> > > > > > "http://www.w3.org/2001/XMLSchema"
> > > > > > xmlns:one="http://namespace1 <http://namespace1/> ">
> > > > > >    <import namespace="http://namespace1 <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
> > 
> > 
> > 
> > 
> 
> 
> 


-- 
Amelia A. Lewis
Architect, TIBCO/Extensibility, Inc.
alewis@tibco.com
Received on Wednesday, 22 October 2003 15:01:36 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:58:27 GMT