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Re: facets, XSD, SCD, external datatypes (was Re: A brief primer on Qnames and URIs)

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Fri, 16 Nov 2007 12:21:51 +0000
Message-ID: <473D8B5F.9030308@hpl.hp.com>
To: Michael Smith <msmith@clarkparsia.com>
CC: Bijan Parsia <bparsia@cs.man.ac.uk>, "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, public-owl-wg@w3.org

Michael Smith wrote:
> 
> On Thu, 2007-11-15 at 12:49 +0000, Jeremy Carroll wrote:
> 
>> With Peter's e-mail, I am confident that we can have:
> 
> I would appreciate if you can confirm my understanding of the items you
> list below.
> 
> 
>> - in-line XSD datatypes with our own syntax
> 
> E.g., the approach of the member submission.

I think so, but I am not that familiar with that approach, ...

> 
> 
>> - in-line XSD datatypes using their syntax (but probably not in RDF/XML; 
>> the xml literals in RDF/XML are defined via exclusive XML 
>> Canonicalization, that is not compatabilte with shipping XML Schema 
>> fragments)
> 
> So, in OWL/XML something like
> 
> ...
> <owl11xml:Datatype>
>   <xsd:SimpleType>
>     <xsd:restriction base="xsd:integer">
>       <xsd:minInclusive value="10"/>
>      </xsd:restriction>
>   </xsd:SimpleType>
> <owl11xml:Datatype>
> ...
> 
> 

That looks cool to me; other people might have other opinions, but there 
are no obvious road blocks when defining our own format.

> And in OWL RDF/XML the constraints you mention force us to redeclare the
> namespace like
> 
> ...
> <owl:DataRange rdf:parseType="Literal">
>   <xsd:SimpleType xmlns:xsd="http://www.w3.org/2001/XMLSchema">
>     <xsd:restriction base="xsd:integer">
>       <xsd:minInclusive value="10"/>
>     </xsd:restriction>
>   </xsd:SimpleType>
> </owl:DataRange>
> ...
> 

In fact,the example you give would work whether or not you include the 
namespace decl. The RDF/XML parser will infer it correctly, as part of 
the XC14N subsystem.

The problem is qnames in attribute values such as base="xsd:integer".
In your example, we are lucky in that the prefix xsd: also occurs 
elsewhere (e.g. on the element name). If it doesn't then there is no 
amount of xmlns declarations that will make it appear in the literal 
value. The XC14N process would strip such an 'unused' namespace decl.



> 
>> - external references to XSD datatypes with an explicit id attribute
>>    [Hence allowing an ontology to be shipped in two files, one 
>> containing all the datatypes]
> 
> As described at http://www.w3.org/TR/swbp-xsch-datatypes/#sec-id-attr 
> 

Yes (not refreshing my memory)


> 
>> The only missing desiderata was external references to arbitrary XSD 
>> datatypes, which does depend on XML Schema's SCD doc.
>> I personally think we should be prepared to cut our losses at that point.
> 
> And you were going to contact the XML Schema WG on the status of that
> work, correct?

I was hoping you might .... :) at least for the initial how's it going? 
But I can if you prefer.

Jeremy
Received on Friday, 16 November 2007 12:22:36 GMT

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