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Re: RDFa Core and RDF/XML

From: Ivan Herman <ivan@w3.org>
Date: Mon, 29 Mar 2010 14:36:30 +0200
Cc: W3C RDFa WG WG <public-rdfa-wg@w3.org>
Message-Id: <312BA44B-1A5A-43CB-8D3B-B510D2BE3CE7@w3.org>
To: Mark Birbeck <mark.birbeck@webbackplane.com>

On Mar 29, 2010, at 14:00 , Mark Birbeck wrote:

> Hi Ivan,
> 
> Could you clarify?
> 
> First you say:
> 
>  The question is: are the triples described by that RDF/XML part of
> what the RDFa
>  processor produces or not? Ie, should the RDFa processor take that
> RDF/XML portion,
>  parse it and add those triples to the generated Graph?
> 
> I.e., two references to *RDFa* processors.
> 
> But the SVG document you quote says:
> 
>  If both are being used for RDF (that is, RDF and RDFa), then an RDF processor
>  should combine them into the same graph.
> 
> I.e., we're now talking about an *RDF* processor.
> 

SVG does not talk separately about an RDFa processor. The complete, relevant quote is:

[[[
SVG provides two mechanisms for adding metadata directly to a document: the 'metadata' element, and several metadata attributes. These different mechanisms may be used independently, or in concert. If both are being used for RDF (that is, RDF and RDFa), then an RDF processor should combine them into the same graph. (Note: metadata attributes should not be used directly on RDF elements.)
]]]

which, I think, has the intent of what I described in terms of an RDFa processor. But I am not an SVG WG member:-)

> I don't see a problem with the latter scenario -- after all it's none
> of our business whether some RDF processor understands RDF/XML, RDFa,
> GRDDL, and so on.
> 
> But I don't think we have anything to say on the former scenario -- an
> RDFa parser can't be expected to parse RDF/XML or anything else for
> that matter.
> 
> But I may have misunderstood what you're driving at.
> 

My intention was indeed that an *RDFa* processor should parse the RDF/XML portion, too, and add it to the RDF graph that is produced. Writing these lines made me realize, however, that this *is* an extra load on an RDFa processor, so it is not so obvious after all:-(

It is certainly true that an engine extracting metadata from an SVG file that wants to be conform to the SVG standard has to do both the RDF/XML and the RDFa processing. But that may be then a tool's own option (my distiller does that).

Whatever we decide, we may want to add an informal note to the RDFa 1.1 Core about this. It is, I think, an obvious questions user may ask themselves.

Ivan


> Regards,
> 
> Mark
> 
> 
> On Mon, Mar 29, 2010 at 12:04 PM, Ivan Herman <ivan@w3.org> wrote:
>> There is a small issue that I would like to raise. I do not think it is particularly controversial but may be worth documenting even in the FPWD.
>> 
>> Let us suppose I have a general XML application, using namespaces. I use RDFa 1.1 in there, that can be used to generate RDF triples. However, because that is a namespace aware XML application, it is perfectly feasible that the user includes an RDF/XML portion into the XML file, too. The question is: are the triples described by that RDF/XML part of what the RDFa processor produces or not? Ie, should the RDFa processor take that RDF/XML portion, parse it and add those triples to the generated Graph?
>> 
>> My opinion is that the answer should be 'yes'. Note also that this is already how SVG metadata is defined:
>> 
>> http://www.w3.org/TR/SVGMobile12/metadata.html
>> 
>> includes the <metadata> elements that can be used as a container of RDF/XML, as well as the possibility of adding RDFa attributes. It also says:
>> 
>> [[[
>> If both are being used for RDF (that is, RDF and RDFa), then an RDF processor should combine them into the same graph. (Note: metadata attributes should not be used directly on RDF elements.)
>> ]]]
>> 
>> I do not think it is a big deal, but it should be noted in the RDFa 1.1. Core if the WG agrees...
>> 
>> Ivan
>> 
>> ----
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> mobile: +31-641044153
>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>> FOAF: http://www.ivan-herman.net/foaf.rdf
>> 
>> 
>> 
>> 
>> 
>> 


----
Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf







Received on Monday, 29 March 2010 12:35:10 GMT

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