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Re: Primer XPackage examples [was Re: Review of RDF primer Revised Editor's Draft 21 July 2003]

From: Frank Manola <fmanola@mitre.org>
Date: Mon, 04 Aug 2003 08:45:50 -0400
Message-ID: <3F2E557E.6090701@mitre.org>
To: Dave Beckett <dave.beckett@bristol.ac.uk>
CC: w3c-rdfcore-wg@w3.org, Eric Miller <em@w3.org>

Dave Beckett wrote:

> On Fri, 01 Aug 2003 19:16:56 -0400
> Frank Manola <fmanola@mitre.org> wrote:
>>Dave (and for everyone's information)--
>>Regarding your comments below on the XPackage examples:
>>I reviewed the XPackage examples again (I *thought* I'd validated them, 
>>and it turns out I had).  The complete example 37 (with all the 
>>namespaces declared) is:
>><?xml version="1.0"?>
>>            xmlns:xpackage="http://xpackage.org/namespaces/2003/xpackage#"
>>            xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>>            xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
>>            xmlns:dc="http://purl.org/dc/elements/1.1/"
>>            xmlns:mime="http://xpackage.org/namespaces/2003/mime#"
>>            xmlns:x="http://xpackage.org/namespaces/2003/xml#"
>>            xmlns:xlink="http://www.w3.org/1999/xlink">
>>     <rdf:RDF>
>>         <rdf:Description rdf:about="urn:example:xhtmldocument-doc">
>>           <rdfs:comment>The XHTML document.</rdfs:comment>
>>           <xpackage:location xlink:href="doc.html"/>
>>           <mime:contentType>application/xhtml+xml</mime:contentType>
>>           <x:namespace rdf:resource="http://www.w3.org/1999/xhtml"/>
>>           <x:style rdf:resource="urn:example:xhtmldocument-stylesheet"/>
>>           <dc:creator>Garret Wilson</dc:creator>
>>           <xpackage:manifest rdf:parseType="Collection">
>>              <rdf:Description
>>                      rdf:about="urn:example:xhtmldocument-stylesheet"/>
>>              <rdf:Description
>>                      rdf:about="urn:example:xhtmldocument-image"/>
>>           </xpackage:manifest>
>>         </rdf:Description>
>>     </rdf:RDF>
>>This validates in the W3C RDF validator.  In the generated triples, the 
>>xpackage:location property has a blank node as its object, and the blank 
>>node in turn has a http://www.w3.org/1999/xlinkhref property whose value 
>>is the literal "doc.html".  Example 38 works the same way.  Does this 
>>not square with your understanding of what's supposed to happen? 
> It does.  What you describe in the first sentence is what I explained
> in my comment.  

Well, maybe we have a terminology problem then, because when you said 
"That is not RDF/XML", I thought you meant it wasn't syntactically 
legal, and wouldn't validate.  It seems to me that that if syntax is not 
legal RDF/XML, a correctly-operating RDF/XML parser should say so. 
Generating non-intuitive results from legal RDF/XML syntax is a separate 
issue (people have expressed amazement as what parseType="Collection" 
does, for example!)

> The point is, the xlink:href is not special, and RDF/XML
> has no special processing for it's value - which looks like a URI.
> It might be misleading if people read it that way.  
>   <xpackage:location xlink:href="doc.html"/>
> makes 2 triples - which I think is only clear if you recognised that
> abbreviation, or tried it out, such as by using a validator:
>   _:a xpackage:location _:b .
>   _:b xlink:href "doc.html" .
> (I'm sad to see this abbreviation used, I would have liked to have killed it)
> Dave

Frank Manola                   The MITRE Corporation
202 Burlington Road, MS A345   Bedford, MA 01730-1420
mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-875
Received on Monday, 4 August 2003 09:26:25 UTC

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