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Re: XHTML 2.0 metainfo question (Correction!!!)

From: Dan Brickley <danbri@w3.org>
Date: Wed, 4 Aug 2004 05:53:24 -0400
To: Mark Birbeck <mark.birbeck@x-port.net>
Cc: public-rdf-in-xhtml-tf@w3.org, 'Masayasu Ishikawa' <mimasa@w3.org>
Message-ID: <20040804095324.GE24080@homer.w3.org>


Thanks for the fix. I was talking with Max Froumentin about 
possibility of XSLTing this notation into standard RDF/XML. It would
seem that every element encodes a property and that the XSLT would spend
a lot of its time inserting 'padding' elements that correspond to nodes
in the graph (untyped and hence written as rdf:Description of
rdfs:Resource according to taste). An alternative idiom would be liberal
use of parseType="Resource" attributes where we have a property pointing
to a more detailed description of something. People seem to have
different instincts about which style of RDF is the ugliest ;)

If I understand correctly, the basic transform we're after is:

[[
<link rel="foaf:maker">
  <meta property="foaf:name">Dan Brickley</meta>
  <link property="foaf:homepage" resource="http://danbri.org/"/>
  <link rel="foaf:knows">
    <meta property="foaf:name">Dan Connolly</meta>
  </link>
</link>

...into:

<rdfs:Resource>
  <foaf:maker>
    <rdfs:Resource>
      <foaf:name>Dan Brickley</foaf:name>
      <foaf:homepage rdf:resource="http://danbri.org/"/>
      <foaf:knows>
        <rdfs:Resource>
          <foaf:name>Dan Connolly</foaf:name>
        </rdfs:Resource>
      </foaf:knows>
    </rdfs:Resource>
  </foaf:maker>
</rdfs:Resource>

]]

A contracted form of the latter is:

<rdf:Description>
  <foaf:maker rdf:parseType="Resource">
      <foaf:name>Dan Brickley</foaf:name>
      <foaf:homepage rdf:resource="http://danbri.org/"/>
      <foaf:knows rdf:parseType="Resource">
          <foaf:name>Dan Connolly</foaf:name>
      </foaf:knows>
  </foaf:maker>
</rdf:Description>

...perhaps this would be a natural target for an XSLT conversion?

Talking of which, more questions:

i) re GRDDL, if a transformation _does_ require XSLT 2.0 (although you
argue in [1] that it can be implemented in 1.0), do we have any way in
GRDDL of expressing this?

ii) are there XSLTs already which consume this new notation and emit
RDF/XML? I was encouraging MaxF to have a go at it, but perhaps the work
is already done...

iii) test cases. Getting a syntax for something like this right can be
tricky, with lots of corner cases. Does the HTML WG have infrastructure
for hosting test cases, perhaps something using the same approach we
used in http://www.w3.org/TR/rdf-testcases/ ie. pairs of files, one in
the relevant XML syntax, the other showing the canonical RDF graph
serialized using the N-Triples notation...   If the HTML WG aren't
likely to do this, perhaps this is something the SWBPD WG could assist
with in some way?

iv)  xml:base, relative URIs in ns declarations etc?

eg. test case:

<link xmlns:foaf="/foaf/0.1/" xml:base="http://xmlns.com/" rel="foaf:maker">
  <meta property="foaf:name">Dan Brickley</meta>
  <link property="foaf:homepage" resource="http://danbri.org/"/>
  <link rel="foaf:knows">
    <meta property="foaf:name">Dan Connolly</meta>
  </link>
</link>

...does this generate the same triples?



I think I've also some question about XML literals but need to re-read
first. On first glance it wasn't clear that this notation could maintain
the distinction RDF has, between XML literals and plain literals that
happen to look like markup.

cheers,

Dan
[1] http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2004Mar/0007.html
   ...re xslt 2, qnames in attributes etc.
Received on Wednesday, 4 August 2004 05:53:41 GMT

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