Re: Possible solutions for ISSUE 97

Hi Ben,

I disagree with you and Ivan, I'm afraid.

Of course, I'm happy to be wrong, since it would make life easier. But
the bit that needs to be worked through is in the RDF Concepts
document. The definition of an XML literal lies there, and in my view
it's quite precise...misguided, but precise.

So however people reply to this view-point, they need to make some
reference to RDF Concepts, and say why my interpretation *of that* is
wrong.

RDF is independent of syntax, so the concept of an XML literal exists
*prior* to putting any triples into the triple store; in other words,
your scheme is wrong, and it needs to be like this:

  (1) we run the RDFa parser on an input document,
  (*) the output of the RDFa parser is RDF
  (2) we take the output of the parser and stuff it into a triple store,
  (3) we SPARQL against the triple store.

If we decide to create XML literals, then (a) that must happen
independent of any triple stores, query interfaces, serialisations,
etc., and (b) those XML literals must conform to the definition
provided in RDF Concepts.

Regards,

Mark

On 19/03/2008, Ben Adida <ben@adida.net> wrote:
>
>
>  [I changed the subject from 87 to 97].
>
>  Ivan wrote:
>  > - However, an implementation of RDFa that produces an RDF graph in some
>  > other serialization (which is the case for a number of our
>  > implementations, though probably not all; it certainly true for Fabien's
>  > xslt script, my stuff, probably Manu's code) has to produce a *valid*
>  > serialized version of the RDF graph.
>
>  After some thought, I've become very wary of implementing a new data
>  type (or even trying to find an existing one in a different space), and
>  I agree with Ivan.
>
>  Yes, an RDFa parser produces an RDF graph. But an RDF graph is an
>  abstract notion, so the only thing an RDFa parser *can* produce is
>  *some* serialization of an RDF graph. As long as that serialization is
>  *a* valid serialization of the correct RDF graph, the RDFa parser is
>  compliant, in my opinion.
>
>  To be more specific, let's examine how we test an RDFa parser:
>    (1) we run the RDFa parser on an input document,
>    (2) we take the output of the parser and stuff it into a triple store,
>    (3) we SPARQL against the triple store.
>
>  Steps (2) and (3) are part of the test harness, they're not part of the
>  RDFa processor.
>
>  So, where does the XMLLiteral canonicalization happen? In my opinion,
>  somewhere between (2) and (3), meaning somewhere in the triple store,
>  *after* the RDFa parser has done its thing. After all, we don't expect
>  the RDFa parser to provide a SPARQL interface, so why should it need to
>  do XMLLiteral canonicalization if it's never performing graph operations?
>
>  So, regarding Test Case 11:
>
>  http://www.w3.org/2006/07/SWD/RDFa/testsuite/xhtml1-testcases/0011.xhtml
>
>  I believe we should include the xmlns declaration, and the SPARQL should
>  read:
>
>  ASK WHERE {
>         <http://www.w3.org/2006/07/SWD/RDFa/testsuite/xhtml1-testcases/0011.xhtml>
>  <http://purl.org/dc/elements/1.1/creator> "Albert Einstein" .
>         <http://www.w3.org/2006/07/SWD/RDFa/testsuite/xhtml1-testcases/0011.xhtml>
>  <http://purl.org/dc/elements/1.1/title>
>  "E = mc<sup xmlns=\"http://www.w3.org/1999/xhtml\">2</sup>: The Most
>  Urgent Problem of Our
>  Time"^^<http://www.w3.org/1999/02/22-rdf-syntax-ns#XMLLiteral> .
>
>  }
>
>
>  -Ben
>
>
>  PS: when we implement RDFa in HTML5, we may have to deal with a
>  different data type. This makes sense: we're extracting markup from the
>  host language, so the type matches the host language. In the current
>  case, it's XML.
>
>


-- 
  Mark Birbeck

  mark.birbeck@x-port.net | +44 (0) 20 7689 9232
  http://www.x-port.net | http://internet-apps.blogspot.com

  x-port.net Ltd. is registered in England and Wales, number 03730711
  The registered office is at:

    2nd Floor
    Titchfield House
    69-85 Tabernacle Street
    London
    EC2A 4RR

Received on Wednesday, 19 March 2008 23:41:17 UTC