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RE: [namespaceDocument-8] RDF and RDDL

From: Williams, Stuart <skw@hplb.hpl.hp.com>
Date: Mon, 8 Apr 2002 13:43:36 +0100
Message-ID: <5E13A1874524D411A876006008CD059F192A8C@0-mail-1.hpl.hp.com>
To: "'Tim Bray'" <tbray@textuality.com>, www-tag@w3.org
Cc: www-tag@w3.org
Hi Tim,

> -----Original Message-----
> From: Tim Bray [mailto:tbray@textuality.com]
> Sent: 08 April 2002 07:09
> To: www-tag@w3.org
> Cc: www-tag@w3.org
> Subject: Re: [namespaceDocument-8] RDF and RDDL
> 
> 
> Williams, Stuart wrote:
> 
> > At last week's TAG telcon I took an action to explore the use of an RDF
> > based approach for embedding machine readable information on RDDL
documents
> > instead of Xlink. 
> 
> I'd like to thank Stuart for all the spadework on this issue, which
> I realize now that I didn't understand before.  I'm not sure that I
> understand it now, but I'm going to suggest another approach based
> on Stuart's work that I think comes out a little cleaner:
> 
> <div ID="schematron" class="resource">
>   <h3>7.7 Schematron</h3>
>        <p>A <a href="rddl.sch">Schematron Schema</a> for RDDL. </p>
>   </div>
> 
> <rdf:description rdf:about="rddl.sch">
>   <rddl:prose rdf:resource="#schematron" />
>   <rddl:purpose
>       rdf:resource="http://www.rddl.org/purposes#schema-validation" />
>   <rddl:nature
>       rdf:resource="http://www.ascc.net/xml/schematron" />
>   </rdf:description>

I quite like this, I also had formulation that looked like (also attached
png):

  <rdf:Description rdf:about="http://www.rddl.org/">
    <rddl:Resource>
      <rdf:Description>
        <rddl:Purpose
rdf:resource="http://www.rddl.org/purposes#schema-validation"/>
        <rddl:Prose rdf:resource="http://www.rddl.org/#schematron"/>
        <rddl:RelatedResource>
          <rdf:Description rdf:about="http://www.rddl.org/rddl.sch"
 
rddl:Nature="http://www.ascc.net/xml/schematron"/>
        </rddl:RelatedResource>
      </rdf:Description>
    </rddl:Resource>
  </rdf:Description>


Which links the namespace with an RDF blank node that represents the RDDL
directory entry. The directory entry carries properties for RDDL purpose,
prose description and related resource. The nature property is attached to
the RDF node that represents the related resource.

One of the things that does concern me a bit is the conflation of the
namespace and the namespace document under a single URI. For example, it is
quite conceivable for an XML Schema to define an element of type "Nature" in
the namespace named by the URI http://www.rddl.org/. The URI reference
http://www.rddl.org/#Nature might then be used to refer to that element
type.

However, it is also conceivable that in an RDDL document there may be some
descriptive prose describing that same element type in a RDDL document
retrivable via the URI that names the namespace eg:

      ...
	<div id="Nature">
		Some descriptive text about the Nature element in the
namespace named http://www.rddl.org/
	</div>
      ...

We are now left with the question of whether http://www.rddl.org/#Nature
names a type of XML element or whether it identifies a fragment within a
RDDL document. Even worse, the fragment in the document could be completely
unrelated to the element in the schema. The use of id's in the namespace
document seem to itself use names from within the namespace - which at best
overload what it is such references refer too (this is irrespective of
choices about Xlink/RDF).

This is of course just a variant of whether http://www.rddl.org/ names a
namespace or a namespace document.

<snip/>
> -Tim
> 

Stuart



Received on Monday, 8 April 2002 08:45:19 GMT

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