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RE: RDFa test suite addition

From: Jeremy Carroll <jeremy@topquadrant.com>
Date: Tue, 29 Jul 2008 13:36:31 -0700
To: "'Toby A Inkster'" <tai@g5n.co.uk>, "'Shane McCarron'" <shane@aptest.com>
Cc: <public-rdf-in-xhtml-tf@w3.org>
Message-ID: <007d01c8f1ba$ca4ceff0$5ee6cfd0$@com>



There are no such things as namespaces in RDF.

It is not clear to me what the ontological status of namespaces in XML is.

For the problem of XXX:YYY from a URIref in RDF/XML, I tend to take YYY as the longest final NCName (and raise an error if none).

Often people organize RDF vocabularies so that all the terms can have the same prefix, and then they call this a namespace. This usage is informal.

Jeremy


-----Original Message-----
From: public-rdf-in-xhtml-tf-request@w3.org [mailto:public-rdf-in-xhtml-tf-request@w3.org] On Behalf Of Toby A Inkster
Sent: Tuesday, July 29, 2008 1:04 PM
To: Shane McCarron
Cc: public-rdf-in-xhtml-tf@w3.org
Subject: Re: RDFa test suite addition


On 29 Jul 2008, at 18:32, Shane McCarron wrote:

> I get what you are saying here... but you scared me with  
> something.  What is Cognition learning about a "namespace" in the  
> context of RDFa?  It should not be learning anything?  There are no  
> namespaces in RDFa.  There are prefix values and suffixes.  And the  
> concatenation of these creates URIs (IRIs) that, when dereferenced,  
> could mean something.  In my opinion Cognition could be learning  
> about those URIs... but the prefix value is meaningless.  Hell, the  
> prefix value could be "http".  It could be "h".  It would be  
> completely legitimate.


As I said, it's not so much a problem with the RDFa parsing, but any  
subsequent RDF/XML output.

Say, for example, we have the following RDFa:

     <div xmlns:ex="http://example.org/ns/" rel="ex:../foo"
     about="http://example.com/">
       Foobar
     </div>

This will be parsed as the following triple:

     <http://example.com/>
       <http://example.org/foo>
         "Foobar".

If the parser then is to output to RDF/XML, the result will be  
something like:

     <rdf:Description
         rdf:about="http://example.com/"
         XXX:YYY="Foobar"
     />

But won't know what to choose for 'XXX' or 'YYY'. I suppose it could  
figure out YYY by finding the last slash or hash sign in the  
predicate, then choose a random string to use for the prefix XXX, but  
the results are unlikely to be pretty.

-- 
Toby A Inkster
<mailto:mail@tobyinkster.co.uk>
<http://tobyinkster.co.uk>
Received on Tuesday, 29 July 2008 20:37:11 GMT

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