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Re: feedback on rdfcore syntax changes: pls allow unqualified about=, etc

From: Graham Klyne <GK@ninebynine.org>
Date: Wed, 23 Oct 2002 11:58:29 +0100
Message-Id: <5.1.0.14.2.20021023114834.03c508e0@127.0.0.1>
To: Dan Brickley <danbri@w3.org>
Cc: <www-rdf-comments@w3.org>

I think it's fine to allow about='...' in an <rdf:Description ...> (or 
<rdf:Resource...> or other <rdf:...> ) element, but that it creates a 
conflict with the  apparent intent of the XML namespaces spec to allow it 
on a typednode production from a different namespace>

Where, for example, does this stand:

    <foaf:Person about="http://www.example.org/Person/Fred">
     :
    </foaf:Person>

?

Suppose an XML schema for the foaf namespace defines an about attribute 
with a different purpose?

#g
--

At 04:28 PM 10/22/02 -0400, Dan Brickley wrote:



> >From #rdfig discussion:
>
>http://ilrt.org/discovery/chatlogs/rdfig/2002-10-22#T20-16-43
>
>[09:10] * danbri realises that all Adobe XMP RDF isn't RDF according to
>current RDFCore RDF/XML syntax
>[09:10] <danbri> they use unqualified 'about="..."'
>[09:10] <dajobe> yeah
>[09:11] <dajobe> but if MikeD gets the namespace change, it'll all be
>broken
>[09:11] <danbri> How would you feel about revisiting that decision in the
>light of implementor feedback?
>[09:11] <danbri> I don't want a namespace change...
>[09:11] <dajobe> I'll wait for the feedback
>[09:11] <dajobe> there's been too much predicting of potential complaints
>[09:11] <DanCon> er... we have the feedback; danbri just checked their
>shipped product.
>[09:12] * DanCon will send it to rdf-comments if that's easier for dajobe
>[09:12] <danbri> I'll do it.
>
>
>I believe the rdfcore decision on about= vs rdf:about=, namely to
>dissallow the former, goes against the chartered commitment to backwards
>compatibility.
>
>http://www.w3.org/2000/10/rdf-tests/rdfcore/rdf-ns-prefix-confusion/error0001.rdf
><!-- Test about - MUST FAIL -->
>
>Currently we say that docs that use the unqualified 'about=' idiom are not
>RDF/XML documents. This includes some examples from the M+S
>RECommendation, as well as the implementation by Adobe in their XMP
>toolkit (and hence a great many PDFs and other files contain
>not-quite-RDF).
>
>We could instead take the line that about= and rdf:about= are specified by
>the RDF/XML syntax to be functionally equivalent, even though they are not
>associated (by the XML Namespace machinery) with a common namespace URI.
>(same goes for rdf:ID and other syntactic gizmos).
>
>See http://www.w3.org/2001/sw/Europe/200206/imagemeta/extract/extract for
>an online tool that extracts RDF/XML from XMP documents, eg see innards of
>http://www.adobe.com/products/framemaker/pdfs/idn2_vs_pm7_vs_fm7_ue.pdf
>
><rdf:RDF xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'
>  xmlns:iX='http://ns.adobe.com/iX/1.0/'>
>  <rdf:Description about=''
>   xmlns='http://ns.adobe.com/pdf/1.3/'
>   xmlns:pdf='http://ns.adobe.com/pdf/1.3/'>
>   <pdf:CreationDate>2002-05-16T10:35:48Z</pdf:CreationDate>
>   <pdf:Producer>Acrobat Distiller 4.05 for Macintosh</pdf:Producer>
>   <pdf:ModDate>2002-05-22T17:22:24-07:00</pdf:ModDate>
>  </rdf:Description>
>
>  <rdf:Description about=''
>   xmlns='http://ns.adobe.com/xap/1.0/'
>   xmlns:xap='http://ns.adobe.com/xap/1.0/'>
>   <xap:CreateDate>2002-05-16T10:35:48Z</xap:CreateDate>
>   <xap:ModifyDate>2002-05-22T17:22:24-07:00</xap:ModifyDate>
>   <xap:MetadataDate>2002-05-22T17:22:24-07:00</xap:MetadataDate>
>  </rdf:Description>
></rdf:RDF>
>
>
>According to M+S '99 REC (which has about='' examples) this is OK.
>According to RDF Core, it isn't. The new RDF syntax spec doesn't make
>clear why such documents are no longer considered RDF, only that they are
>not. Perhaps there is a case based on parser complexity, efficiency etc.,
>but I've not yet seen it made strongly enough to justify the backwards
>compatibility hit.
>
>Dan
>
>
>--
>mailto:danbri@w3.org
>http://www.w3.org/People/DanBri/

-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Wednesday, 23 October 2002 06:40:15 GMT

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