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ISSUE http://www.w3.org/2000/03/rdf-tracking/#rdfms-xml-base

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Mon, 14 Jan 2002 15:39:15 +0000
To: w3c-rdfcore-wg@w3.org
Message-ID: <16582.1011022755@tatooine.ilrt.bris.ac.uk>

This issue was raised by Ron Daniel in
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0097.html

I did an analysis of previous discussion (below) of which the summary is:

  We decided that xml:base resolution for standalone RDF/XML was not
  allowed at present but made no decision on RDF/XML embedded in other XML. 
  -- http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0391.html

but the issue wasn't closed (June 2001) and we now really need to get
this out of the way.  The easiest route is to say we don't provide a
meaning for xml:base in embedded RDF/XML either.

I've been told ARP already handles xml:base, and will continue to support it:

  "xml:base is fully supported, both in RDF/XML and any document
  embedding RDF/XML."
  -- http://www.hpl.hp.co.uk/people/jjc/arp/

and I note that SVG (A W3C recommendation) gives an example of
embedded RDF/XML inside SVG: 
  http://www.w3.org/TR/2001/REC-SVG-20010904/metadata.html
and SVG does allow xml:base
  http://www.w3.org/TR/SVG/struct.html#XMLBaseAttribute

So the other alternative, sigh, is to revisit the entire issue and
allow/support xml:base throughout - but see the discussion below for
potential impact on existing applications.

Dave


----------
Previous discussion starting from Jan Grant's summary at
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0022.html

which I might summarise as

  Out of charter
   [[
     Our Charter[CHART] says that
       "The RDF Core WG is neither chartered to develop a new RDF
       syntax, nor to reformulate the RDF model". 
     It also says that
       "Backwards compatibility with existing RDF applications
        is a priority for the RDF Core Working Group". 
   ]] -- RonD, 
   http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0118.html

   Seconded by DanC
   http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0119.html

   Sympathy from DanBri
   http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0178.html


  Impact on existing apps / Back Compat argument spurious; OK with
  Ron's proposal if this is noted.
    JanG
    http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0180.html

  Please allow it in an mixed namespace context
    MartynH
    http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0212.html


Other notes in the thread were the suggestion to add words like
 
  unknown attributes in the xml namespace should not generate triples

to cover such cases as this.  This is already defined in XML as a
special case, but saying it explicitly may help get this noticed.


This proposal of Ron was discussed in 15 June 2001 meeting and agreed:

  "AGREED: ron's proposal to not add xml:base to current syntax, but
   need to address issue of RDF embedded in some other document that
   does have xml:base

   Call for volunteer:  write up resolution for latter case -- Jan volunteers

   ACTION: Jan - write up interpretation of RDF embedded in documents
   with xml:Base"

  -- http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0391.html


JanG wrote this up as a modification of M&S para 204
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0340.html

and then objected to it himself in
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0521.html

  DanC also didn't like the 0340 wording and abstained on it in
  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0525.html


JanG proposed a new wording for updating http://ioctl.org/rdf/ms/rdfms#204

OLD P204:
  "URI-References are resolved to resource identifiers by first
  resolving the URI-reference to absolute form as specified by [URI]..."
INSERT NEW:
  "...using the base URI of the document in which the RDF statements
  appear.

  In the case of RDF which is embedded within other XML, the base URI
  of the embedded RDF shall be taken as the base URI of an element
  appearing at the same position in the containing document. That is,
  the effect of any mechanism that the containing document might use
  to specify a base URI* is 'inherited' by the contained RDF.

  In the case of serialised RDF which does not naturally have a base
  URI (for instance, RDF transmitted as part of an HTTP request), the
  meaning of relative URIs is undefined, except where the transport
  protocol specifies a mechanism for supplying a base URI, in which
  case that base URI is used if supplied.

  If a fragment identifier..."
OLD P204:
  "...is included in the URI-reference then the resource identifier
  refers only to a subcomponent of the containing resource; this
  subcomponent is identifed by the corresponding anchor id internal
  to that containing resource and the extent of the subcomponent is
  defined by the fragment identifier in conjunction with the content
  type of the containing resource, otherwise the resource identifier
  refers to the entire item specified by the URI."

  * substitute XML format of your choice here.

  -- http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jun/0521.html


However JanG then said it was starting to look fuzzy and maybe worth
postponing until
  http://www.w3.org/2000/03/rdf-tracking/#rdfms-fragments
was sorted.

And discussion ended.
Received on Monday, 14 January 2002 10:39:16 EST

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