W3C home > Mailing lists > Public > public-rdf-in-xhtml-tf@w3.org > March 2008

Re: Possible solutions for ISSUE 97

From: Mark Birbeck <mark.birbeck@x-port.net>
Date: Thu, 20 Mar 2008 14:59:04 +0000
Message-ID: <a707f8300803200759u6968e99t1c5843784809dbf2@mail.gmail.com>
To: "Ivan Herman" <ivan@w3.org>
Cc: "Ben Adida" <ben@adida.net>, public-rdf-in-xhtml-tf@w3.org

Hi Ivan,

On 20/03/2008, Ivan Herman <ivan@w3.org> wrote:
> Mark,
>  I still need to understand something in your arguments.
>  Let us take this RDFa:
>  <html xmlns="http://www.w3.org/1999/xhtml"
>        xmlns:q="http://b.b.b">
>  <head>
>  </head>
>  <body>
>    <div about="http://a.b.c" property="q:r"><span>ABC</span></div>
>  </body>
>  </html>
>  Say that my implementation generates the following RDF/XML.
>  <rdf:RDF xmlns:rdf="....">
>     <rdf:Description rdf:about="http://a.b.c">
>       <q:r rdf:parseType="Literal"><span
>  xmlns='http://www.w3.org/1999/xhtml'>ABC</span></q:r>
>     </rdf:Description>
>  </rdf:RDF>
>  Note that the content of the <q:r> is _not_ canonicalized XML, because I
>  use xmlns='...' instead of xmlns="...". So my questions
>  1. Is this RDF/XML portion, in your view, valid RDF/XML?

Yes, it is, since RDF/XML as a serialisation of an RDF graph does not
prohibit you from using apostrophes.

>  2. Is this output conformant with the RDFa syntax definition?

In what way? I'm having trouble seeing what RDFa has to say about
RDF/XML serialisations at all. Or N3, or Turtle, or any other
serialisation of an RDF graph.

We went to a lot of trouble to ensure that RDFa was all about RDF, and
therefore independent of any particular serialisation. (Hence defining
everything in terms of an RDF graph.)

>  My claim is that the answer on both questions are 'yes'. And, in my
>  view, the RDFa syntax document should make that clear.

Although the answer to the first question ("is this valid RDF/XML") is
'yes', that's not the same question as "is this a correct
serialisation of the RDFa". To go from RDFa to RDF/XML you have to go:

  RDFa --> RDF --> RDF/XML

which means you must have created an abstract graph (the RDF in the
middle), which in turn means you must have canonicalised the XML. So
to produce the RDF/XML that you have, with a literal that is
non-canonicalised, you must have substituted the quotes for
apostrophes! Your implementation must have de-canonicalised. :)

(But that doesn't matter, because if you parser that and convert it to
an abstract graph, it will get normalised again; it's just an odd
thing to do.)

To say again, just because you can represent something as valid
RDF/XML, doesn't mean therefore that the abstract graph can take
exactly the same form.



  Mark Birbeck

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Received on Thursday, 20 March 2008 14:59:41 UTC

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