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Re: proposal: Structured Datatypes

From: Jonathan Borden <jonathan@openhealth.org>
Date: Wed, 6 Nov 2002 22:03:57 -0500
Message-ID: <005601c2860a$50f91010$7c674544@ne.mediaone.net>
To: "Dan Connolly" <connolly@w3.org>
Cc: <www-webont-wg@w3.org>

Dan Connolly wrote:

> On Tue, 2002-11-05 at 21:29, Jonathan Borden wrote:
...
> >
> > For the interim I propose when rdfs:range restrictions on
> > owl:DatatypeProperty classes are URIs that identify XML datatypes
(leaving
> > alone for the moment the question about how one associates a URI with an
XML
> > datatype)
>
> ???
>
> How can we leave that aside?
>
> That's critical to making it work, no?

I don't think so. I have the idea of a reasoner that might understand some
types (sic) of types e.g. XML Schema, or other types such as RELAXNG, or XML
Query ... given a URI such a reasoner would have to 'know' how to deal with
it, and I anticipate that some encountered URIs wouldn't be understood. I
would leave it, perhaps, to load in modules that might compare different XML
fragments for equality given a particular URI type e.g.

<int>00010</int> vs. <int>0010</int>

Nonetheless it *is* possible to associate URIs with XML Schema fragments.
For example the mechanism used by the XML Schema WG to associate URIrefs
with XML Schema primitive types e.g.

http://www.w3.org/2001/XMLSchema.xsd
[[
<?xml version='1.0' encoding='UTF-8'?>
<!-- XML Schema schema for XML Schemas: Part 1: Structures -->
<!-- Note this schema is NOT the normative structures schema. -->
<!-- The prose copy in the structures REC is the normative -->
<!-- version (which shouldn't differ from this one except for -->
<!-- this comment and entity expansions, but just in case -->
<!DOCTYPE xs:schema PUBLIC "-//W3C//DTD XMLSCHEMA 200102//EN"
"XMLSchema.dtd" [

<!-- provide ID type information even for parsers which only read the
     internal subset -->
<!ATTLIST xs:schema          id  ID  #IMPLIED>
<!ATTLIST xs:complexType     id  ID  #IMPLIED>
...
<!ATTLIST xs:element     id  ID  #IMPLIED>

...

 <xs:element name="sequence" type="xs:explicitGroup" id="sequence">
  <xs:annotation>
   <xs:documentation
source="http://www.w3.org/TR/xmlschema-1/#element-sequence"/>
  </xs:annotation>
 </xs:element>
]]

and so the URIref for "xsd:sequence" is
http://www.w3.org/2001/XMLSchema#sequence

This is because the XML Schema for XML Schema explicitly has an
'id="sequence"' which is one way that application/xml provides for fragment
id syntax (attributes of type ID)

>
> i.e. that why I proposed we postpone the issue.
>   # why 4.3 Structured Datatypes should wait
>   Dan Connolly (Wed, Oct 23 2002)
>   http://lists.w3.org/Archives/Public/www-webont-wg/2002Oct/0157.html

And on *that* basis alone, 4.3 ought not wait (I've shown a mechanism for
associating URIrefs with XML Schema particles).

>
> > that the lexical value of the owl:DatatypeProperty be an RDF
> > datatype conforming to the syntax of rdf:XMLLiteral and that this
fragment
> > of XML be valid with respect to the particular XML datatype (e.g. XML
Schema
> > particle)
> >
> > For example suppose the XML Schema particle
> >
> > < xsd:complexType name =" xType " id="xType">
> >  < xsd:sequence >
> >    < xsd:element name ="a" type =" xsd:int " minOccurs =" 0 " />
> >    < xsd:element name ="b" type =" xsd:string " minOccurs =" 0 " />
> >  </ xsd:sequence >
> > </ xsd:complexType >
> >
> > then (modulo base URIs)
>
> exactly what URI to use is the 1st question our users will ask.
> How can we put this in our spec without answering that question?

In this case supposing the XML Schema particle is at
http://example.org/Schema

http://example.org/Schema#xType is the correct URI (assuming that
<!ATTLIST xsd:complexType id ID #IMPLIED> has been declared in the internal
subset)

Jonathan
Received on Wednesday, 6 November 2002 22:23:28 GMT

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