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RE: RDF and xml:base

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Fri, 01 Jun 2001 10:49:31 +0100
Message-ID: <3B17652B.25A983EA@hplb.hpl.hp.com>
To: www-rdf-interest@w3.org
Ron,

Thanks for picking this up.  I have added

  http://www.w3.org/2000/03/rdf-tracking/#rdfms-xml-base

to the issues list.

Brian


> RE: RDF and xml:base
> 
> From: Ron Daniel (rdaniel@interwoven.com)
> Date: Wed, May 09 2001
> 
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>   --------------------------------------------------------------------------------
> 
> From: "Ron Daniel" <rdaniel@interwoven.com>
> To: "Aaron Swartz" <aswartz@swartzfam.com>, "RDF Interest" <www-rdf-interest@w3.org>
> Date: Wed, 9 May 2001 12:59:34 -0700
> Message-ID: <EMEKICCGFEKJFGKMFLEPAEOLCHAA.rdaniel@interwoven.com>
> Subject: RE: RDF and xml:base
> 
> Aaron asks:
> 
> > I'm unaware of how xml:base should be used in RDF. Are their any
> > thoughts on
> > this as an interoperability consideration, etc.?
> 
> Sure. First, the RDF community needs to see if XML Base has any
> special impact on us. If it has a special impact on us, then we
> need to start yelling. If it does not, then it is really an XML
> feature that is almost orthogonal to our concerns. In that case,
> I don't think we need to put special provision for it into any
> revision of the model, unlike xml:lang, which may have
> a need for being reflected in the model.
> 
> If we find that xml:base has no SPECIAL impact on us, we should
> just do the typical steps of:
> 1) putting examples of its use into a future revision of the
>    Syntax spec.
> 2) encouraging parser writers to add support for it to their
>    software.
> 3) cautioning creators of descriptions that use of the xml:base
>    attribute may harm interoperability for the next year or so until
>    parsers that deal with it are more widespread. However, they are
>    free to use it if they want.
> 
> > What parsers implement this?
> 
> Right now? None that I know of, although adding it to RDFFilter
> looks fairly straightforward.
> 
> All of this is contingent on the question of whether the XML Base
> proposal has any special impact on RDF. So let's talk about that.
> 
> I currently believe that xml:base does not have any special impact
> on RDF, although it may be of limited utility.
> 
> All that the XML Base proposal does is
> give a way of setting a base URI to use when absolutizing relative
> URI references in XML documents. While RDF documents are rife with
> URI references, few of them are relative. For example, the description
> 
>   <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>            xmlns:dc="http://purl.org/dc/elements/1.1/">
>     <rdf:Description rdf:about="huh.txt">
>       <dc:creator>J. Smith</dc:creator>
>       <dc:subject rdf:resource="http://example.com/codes#foo"/>
>       <dc:subject rdf:resource="http://example.com/codes#bar"/>
>     </rdf:Description>
>   </rdf:RDF>
> 
> contains 1 relative reference ("huh.txt"), 6 QNames which are
> URI references according to the RDF concat rule (rdf:RDF,
> rdf:Description, rdf:about, dc:creator, dc:subject, rdf:resource),
> and four absolute URI references (the two namespace URIs, plus
> "http://example.com/codes#foo/" and "http://example.com/codes#bar/").
> 
> The one relative reference requires a base be established. Typically
> the base is the current document, see RFC 2396 for the 4 rules on
> how to come up with a base URI. So this description assumes it is in
> a file in the same directory as huh.txt.
> 
> We could use xml:base to eliminate the duplicate URI in the /foo
> and /bar subject codes - ala
> 
>   <rdf:Description xml:base="http://example.com/codes" ...
>      ...
>      <dc:subject rdf:resource="foo"/>
>      <dc:subject rdf:resource="bar"/>
>      ...
> 
> The problem here is that the only places to hang a single xml:base
> attribute so we can eliminate the duplication will also make it apply
> to the value of the rdf:about attribute - which makes life hard when
> trying to say what file something applies to.
> 
> On the other hand, if someone wanted to model their problem as
> having one subject arc with a Bag of values, then xml:base is
> more useful:
> 
>   <rdf:Description rdf:about="huh.txt">
>     ...
>     <dc:subject xml:base="http://example.com/codes">
>       <rdf:Bag>
>         <li  rdf:resource="foo"/>
>         <li rdf:resoruce="bar"/>
>       </rdf:Bag>
>       ...
> 
> So - I think xml:base is not harmful but will have limited value in
> many RDF descriptions. No need to preclude, but no need to accelerate.
> 
> Regards,
> 
> Ron Daniel Jr.
> Standards Architect
> Tel: +1 415 778 3113
> Fax: +1 415 778 3131
> Email: rdaniel@interwoven.com
> 
> Visit www.interwoven.com
> Moving Business to the Web
> 
>   --------------------------------------------------------------------------------
> 
>    * Next message: W.M. Jaworski: "RE: Language? [3]"
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>    * Next in thread: Aaron Swartz: "Re: RDF and xml:base"
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Received on Friday, 1 June 2001 05:50:27 GMT

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