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Re: Clarify 'scope' of {element declarations} and {type definitions} re SparqlQuerySimplified-1G

From: John Kaputin (gmail) <jakaputin@gmail.com>
Date: Thu, 11 Jan 2007 14:43:39 +0000
Message-ID: <4c2ae8f80701110643w1372cdb6jb0b69b16f380c4c6@mail.gmail.com>
To: www-ws-desc@w3.org
Cc: "Roberto Chinnici" <Roberto.Chinnici@sun.com>, "Arthur Ryman" <ryman@ca.ibm.com>, "Jonathan Marsh" <jonathan@wso2.com>, "John Kaputin" <KAPUTIN@uk.ibm.com>, woden-dev@ws.apache.org, www-ws-desc-request@w3.org
I like Roberto's suggestion that the component model should contain only the
element declarations and type definitions that are *referenceable* in the
component model - that is, only those from schemas inlined, or whose
namespace is imported, within a wsdl:types element in the root description
or in a wsdl:imported description.

The only assertion that deals with schema referencability is Schema-0016 but
this is a document assertion, not a component model assertion. This can be
used to validate references to schema components within the WSDL infoset,
but note that this checks the validity of the reference, not the
referenceability of the schema components themselves.

Let's suppose Schema-0016 is violated because the 'element' attribute of a
<wsdl:fault> refers to an element declaration in a schema that is not
inlined or imported within a wsdl:types element, then let's examine what
this means for the component model.

1)  If the Description's {element declarations} property contains *all* of
the schema elements:

then the InterfaceFault {element declaration} property will resolve to an
ElementDeclaration, albeit to one that is not referenceable by the
WSDL 2.0document. For a read-only use case that parses a WSDL document
into a
component model, an implementation can probably just infer from the
Schema-0016 violation that there is a problem in the component model (e.g.
by tying the underlying infoset to the component model, it can map the
wsdl:fault's element reference error to the InterfaceFault component).  But
for a component model authoring use case where an InterfaceFault component
is changed to refer to an ElementDeclaration that is not referenceable, it
is not clear how to detect this problem because the spec is silent on the
possibility of non-referenceable ElementDeclarations. The only way to
re-validate the component model is to go back to the underlying infoset and
check assertion Schema-0016.

There's a usability problem too - the WSDL author might modify the
InterfaceFault to refer to an ElementDeclaration that was available in the
Description's {element declarations} property, only to find out when the
component model is re-validated that the chosen Element Declaration is not
referenceable. It might still seem odd to the WSDL author that they are
offered element declarations that they cannot use.

It might be better if the spec included a boolean property of
ElementDeclaration indicating whether it is referenceable or some suitable
component model assertion that an application can use to decide how to
handle non-referenceable ElementDeclarations (e.g. suppress them or display
them disabled/greyed-out).

2) If the Description's {element declarations} property contains only the
*referenceable* schema elements:

then this eliminates the possibility of modifying a component reference to
an ElementDeclaration that is not referenceable and it eliminates the need
for the boolean property or component model assertion described above, but
it does mean that theInterfaceFault's {element declaration} property will be
empty if in the infoset the wsdl:fault violated Schema-0016. So the
InterfaceFault will have a dangling reference and assertion
QName-resolution-1219000 will be violated.

I prefer option 2).  This applies to {type definitions} too.

regards,
John Kaputin.


On 1/10/07, Roberto Chinnici <Roberto.Chinnici@sun.com > wrote:
>
>
> Arthur,
>
> I wasn't arguing that we should keep in the model only *referenced*
> components. My proposal was to add only *referenceable* components, i.e.
> all schema components whose namespace is the target of a xs:schema or
> xs:import element under wsdl:types (in the root WSDL document or in any
> imported one). There is no pruning step involved in doing so.
> Referenceable components satisfy the tools requirements you mention
> quite nicely, because they are precisely the components that you may
> reference from a WSDL component while authoring a WSDL document. In the
> case of built-in schema types, since they are always referenceable,
> they'd never be pruned (there is no pruning).
>
> Thanks,
> Roberto
>
> Arthur Ryman wrote:
> >
> > Roberto,
> >
> > It is simpler to include the components that are encountered when
> > schemas are parsed. Otherwise you'd have to post process the component
> > model and prune out unreferenced schema components, even in imported
> > namespaces.
> >
> > Given that you have to parse the schemas as you encounter them, i.e.
> > to locate referenced components, what is the benefit of the additional
> > postprocessing step to prune out unreferenced ones?
> >
> > Also, for consistency, wouldn't we also have to prune out any of the
> > unreferenced built-in schema types?
> >
> > I can think of good uses for keeping the unreferenced components, e.g.
> > to assist in authoring. Suppose you want an editor to update a WSDL
> > 2.0 document. You should be able to reference any visible components
> > in the imported schema whether or not some other component referenced
> > them previously. Therefore they should be available in the component
> > model, i.e. you don't want to have to reparse the imported schemas.
> > Furthermore, some of the constraints in the spec imply conditions on
> > the structure of element declarations, e.g. the IRI style. So even
> > though WSDL components don't directly reference some types, the
> > constrains refer to the structure and therefore reference them
> > indirectly. e.g. the type of child elements or an input message.
> >
> > It would also be expensive to validate the component model, since for
> > each element or type component, you'd have to scan the component model
> > for a reference to it (like a gc mark and sweep).
> >
> > Arthur Ryman,
> > IBM Software Group, Rational Division
> >
> > blog: http://ryman.eclipsedevelopersjournal.com/
> > phone: +1-905-413-3077, TL 969-3077
> > assistant: +1-905-413-2411, TL 969-2411
> > fax: +1-905-413-4920, TL 969-4920
> > mobile: +1-416-939-5063, text: 4169395063@fido.ca
> >
> >
> > *Roberto Chinnici <Roberto.Chinnici@Sun.COM>*
> > Sent by: www-ws-desc-request@w3.org
> >
> > 01/10/2007 12:53 PM
> >
> >
> > To
> >       Arthur Ryman/Toronto/IBM@IBMCA
> > cc
> >       Jonathan Marsh < jonathan@wso2.com>, "'John Kaputin'"
> > <KAPUTIN@uk.ibm.com>, woden-dev@ws.apache.org, www-ws-desc@w3.org,
> > www-ws-desc-request@w3.org
> > Subject
> >       Re: Clarify 'scope' of {element declarations} and {type
> definitions}
> > re SparqlQuerySimplified-1G
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > This should be a new issue. I'm not convinced by the arguments in this
> > thread.
> >
> > I find the argument by analogy with XML Schema unconvincing. When it
> > comes to WSDL importing/including WSDL, it's fine to base our approach
> > on the schema importing/including schema case, but the WSDL importing
> > schema scenario is qualitatively different, since we're talking of
> > cross-description-language importing.
> >
> > Given that we are defining the WSDL spec, not the XML Schema spec, we
> > don't need to bother with validity of the component model at the schema
> > level. So schema components that are not referenceable by WSDL
> > components need not appear in the WSDL component model, because they
> > don't affect WSDL validity per se.
> >
> > This is the case of components defined by a schema S1 imported by a
> > schema S2 which is in turn imported by WSDL document W. It's only if W
> > imports S1 that those components need to appear in the component model.
> >
> > This approach also makes the rules in 2.17 of part 1 [1] stronger,
> > because the {element declarations} and {type definitions} sets will then
> > be of minimal size (= they will not contain any components that are not
> > referenceable). This seems a desirable property for an interchange
> > format too: to contain all elements/types which could ever be used, but
> > not more.
> >
> > [1]
> >
> http://dev.w3.org/cvsweb/~checkout~/2002/ws/desc/wsdl20/wsdl20.html?content-type=text/html;%20charset=utf-8#qnameres<http://dev.w3.org/cvsweb/%7Echeckout%7E/2002/ws/desc/wsdl20/wsdl20.html?content-type=text/html;%20charset=utf-8#qnameres>
> >
> > Thanks,
> > Roberto
> >
> > Arthur Ryman wrote:
> > >
> > > ++1
> > >
> > > Also, WSDL 2.0 works that way. If A.wsdl imports namespace B then any
> > > components in B's component model are also in A's, otherwise you'd get
> > > dangling component references.
> > >
> > > Arthur Ryman,
> > > IBM Software Group, Rational Division
> > >
> > > blog: http://ryman.eclipsedevelopersjournal.com/
> > > phone: +1-905-413-3077, TL 969-3077
> > > assistant: +1-905-413-2411, TL 969-2411
> > > fax: +1-905-413-4920, TL 969-4920
> > > mobile: +1-416-939-5063, text: 4169395063@fido.ca
> > >
> > >
> > > *"Jonathan Marsh" <jonathan@wso2.com >*
> > > Sent by: www-ws-desc-request@w3.org
> > >
> > > 01/09/2007 05:31 PM
> > >
> > >
> > > To
> > > Arthur Ryman/Toronto/IBM@IBMCA, < woden-dev@ws.apache.org >
> > > cc
> > > "'John Kaputin'" <KAPUTIN@uk.ibm.com>, < woden-dev@ws.apache.org>,
> > > <www-ws-desc@w3.org>
> > > Subject
> > > RE: Clarify 'scope' of {element declarations} and {type definitions}
> > > re SparqlQuerySimplified-1G
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > +1. The visibility of imported components for the purpose of resolving
> > > QName references is a separate matter than the presence of imported
> > > components in the component model. Not very obvious, but AIUI that's
> > > the way schema works and we're following down that path for better or
> > > worse.
> > >
> > > *Jonathan Marsh* - http://www.wso2.com < http://www.wso2.com/> -
> > > http://auburnmarshes.spaces.live.com
> > > <http://auburnmarshes.spaces.live.com/>
> > >
> > >
> > > *From:* www-ws-desc-request@w3.org [mailto:www-ws-desc-request@w3.org]
> > > *On Behalf Of *Arthur Ryman*
> > > Sent:* Tuesday, January 09, 2007 12:53 PM*
> > > To:* woden-dev@ws.apache.org *
> > > Cc:* John Kaputin; woden-dev@ws.apache.org; www-ws-desc@w3.org*
> > > Subject:* Re: Clarify 'scope' of {element declarations} and {type
> > > definitions} re SparqlQuerySimplified-1G
> > >
> > >
> > > John,
> > >
> > > As we discussed on the Woden telecon, the component model should
> > > create ElementDeclaration and TypeDefinition components for all the
> > > element and type definitions that are contained in any schema
> > > (inlined, imported, or included).
> > >
> > > Arthur Ryman,
> > > IBM Software Group, Rational Division
> > >
> > > blog: http://ryman.eclipsedevelopersjournal.com/
> > > phone: +1-905-413-3077, TL 969-3077
> > > assistant: +1-905-413-2411, TL 969-2411
> > > fax: +1-905-413-4920, TL 969-4920
> > > mobile: +1-416-939-5063, text: 4169395063@fido.ca
> > >
> > > *"John Kaputin (gmail)" < jakaputin@gmail.com>*
> > >
> > > 01/09/2007 08:02 AM
> > >
> > >
> > > Please respond to
> > > woden-dev@ws.apache.org
> > >
> > >
> > >
> > > To
> > > www-ws-desc@w3.org
> > > cc
> > > woden-dev@ws.apache.org, "John Kaputin" < KAPUTIN@uk.ibm.com>
> > > Subject
> > > Clarify 'scope' of {element declarations} and {type definitions} re
> > > SparqlQuerySimplified-1G
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > I would like clarification the WSDL 2.0 testcase
> > > SparqlQuerySimplified-1G and which schema element declarations should
> > > be present in the {element declarations} property of the Description
> > > component. I think I had a conversation about this issue with Jonathan
> > > and Arthur driving out to Niagra Falls at the July interop.
> > >
> > > The baseline component model interchange format for this testcase
> > > includes an element declaration whose namespace is not inlined or
> > > imported within the WSDL document's <types> element.
> > >
> > > Baseline sparql-protocol-query.canonical.wsdlcm contains this item:
> > >
> > > <elementDeclarationComponent xml:id="c22">
> > > <name>
> > > <base:namespaceName> http://www.w3.org/1999/02/22-rdf-syntax-ns#
> > > < http://www.w3.org/1999/02/22-rdf-syntax-ns> </base:namespaceName>
> > > <base:localName>RDF</base:localName>
> > > </name>
> > > <system> http://www.w3.org/2001/XMLSchema
> > > < http://www.w3.org/2001/XMLSchema> </system>
> > > </elementDeclarationComponent>
> > >
> > > This element declaration is defined in a schema which is imported by
> > > the <xs:schema> element inlined within the <types> element of
> > > sparql-protocol-query.wsdl. However, the namespace
> > > http://www.w3.org/1999/02/22-rdf-syntax-ns#
> > > < http://www.w3.org/1999/02/22-rdf-syntax-ns> is not xs:imported
> > > directly within the <types> element.
> > >
> > > According to Part 1, section 3.1 Using W3C XML Schema Description
> > > Language:
> > > Schema-0016 "A WSDL 2.0 document MUST NOT refer to XML Schema
> > > components in a given namespace unless an xs:import or xs:schema
> > > element information item for that namespace is present ..."
> > >
> > > In implementing Woden, I interpreted this to mean that {element
> > > declarations} and {type definitions} only contain schema components
> > > whose namespace is inlined or imported directly within the <types>
> > > element. The Woden sparql-protocol-query.canonical.wsdlcm file refects
> > > this, in that the element declaration mentioned above is not present
> > > (and Woden is failing the testcase accordingly).
> > >
> > > However, it may be that the intention of the WSDL 2.0 authors is that
> > > ALL global element declarations and type definitions referenceable by
> > > XML Schema MUST be included in {element declarations} and {type
> > > definitions}, regardless of whether they are inlined or imported
> > > directly within <types> or whether they are 'nested' imports within
> > > those directly inlined or imported schemas, and that assertions like
> > > Schema-0016 only apply when WSDL 2.0 components like InterfaceFault
> > > and InterfaceMessageReference resolve their 'element' QNames to
> > > ElementDeclarations (but not to the contents of {element declarations}
>
> > > and {type definitions} themselves).
> > >
> > > Can someone from the working group please explain which interpretation
> > > is correct?
> > >
> > > Thanks,
> > > John Kaputin
> > >
> >
> >
> >
>
>
>
Received on Thursday, 11 January 2007 14:43:45 GMT

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