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

From: Dan Brickley <danbri@w3.org>
Date: Tue, 22 Oct 2002 17:27:35 -0400 (EDT)
To: www-rdf-comments <www-rdf-comments@w3.org>
Message-ID: <Pine.LNX.4.30.0210221715030.26255-100000@tux.w3.org>

A couple more cases: mozilla, rss...

I might also add that Mozilla 1.2 still uses the about= and resource=
variant. On my Win2K installation, I find a bunch of RDF files (largely
internal configuration / state serializations) most all of which would not
by current RDF Core syntax rules count as legal RDF:


RSS 1.0

This has also been an issue with the RSS 1.0 data format, see
http://web.resource.org/rss/1.0/ -> http://web.resource.org/rss/1.0/spec

        <rdf:li resource="http://xml.com/pub/2000/08/09/xslt/xslt.html" />
        <rdf:li resource="http://xml.com/pub/2000/08/09/rdfdb/index.html" />

An RDF Seq (sequence) is used to contain all the items rather than an RDF
Bag to denote item order for rendering and reconstruction.

Syntax: <items><rdf:Seq><rdf:li resource="{item_uri}" /> ...  </rdf:Seq></items>

The RSS 1.0 spec was written against W3C's M+S REC in 2000, before RDF
Core got underway. The RSS-DEV group has discussed whether to change its
specification of the rdf:Seq syntax to track RDFCore's syntax change, but
(I believe) has decided to hang on and see what happens, before upsetting
RSS implementors.

Also in my earlier post, I forgot to cite the RDF issues list:


On Tue, 22 Oct 2002, 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
Received on Tuesday, 22 October 2002 17:27:36 UTC

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