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Re: SPARQL Results Format and Unbound Variables [OK?]

From: Jeen Broekstra <jeen.broekstra@aduna.biz>
Date: Wed, 21 Dec 2005 12:41:14 +0100
Message-ID: <43A93F5A.1080903@aduna.biz>
To: Ron Alford <ronwalf@umd.edu>
CC: public-rdf-dawg-comments@w3.org


The WG has considered your comments carefully [1][2] and has decided[3]
to change the Query Results XML Format in response to your comments.

In brief, the changes correspond to the 'collapsed' syntax variation you
described, that is, an unbound variable is represented by simple
omission of a <binding> element. As a consequence, the restriction that
binding elements in a result are in the same order as the corresponding
variable elements in the header is also dropped.

The changes are reflected in the current version of the editor's draft:

  http://www.w3.org/2001/sw/DataAccess/rf1/

Specifically, the wording in section 2.2 linking ordering of binding
elements to ordering of variable elements was stricken.

Addtionally, section 2.3.1 now reads:

[[
   Each result element corresponds to one Query Solution in a result and
   contains child elements (in no particular order) for each Query
   Variable that appears in the solution. It is used to record how the
   query variables bind to RDF Terms.

   Each binding inside a solution is written as an element binding as a
   child of result with the query variable name as the value of the name
   attribute. So for a result binding two variables x and hpage it would
   look like:

  [...]

   The value of a query variable binding, which is an RDF Term, is
   included as the content of the binding as follows:

RDF URI Reference U
     <binding><uri>U</uri></binding>
RDF Literal S
     <binding><literal>S</literal></binding>
RDF Literal S with language L
     <binding><literal xml:lang="L">S</literal></binding>
RDF Typed Literal S with datatype URI D
     <binding><literal datatype="D">S</literal></binding>
Blank Node label I
     <binding><bnode>I</bnode></binding>

   If, for a particular solution, a variable is unbound, no binding
   element for that variable is included in the result element.
]]

Please let us know whether this response addresses your comment to your
satisfaction. If it does, please respond with [CLOSED] in the
subject to allow the issue tracking scripts to close this issue.

Regards,

Jeen

[1] http://lists.w3.org/Archives/Public/public-rdf-dawg/2005OctDec/0009
[2] http://lists.w3.org/Archives/Public/public-rdf-dawg/2005OctDec/0318
[3] http://www.w3.org/2005/12/20-dawg-minutes.html#action01
-- 
Jeen Broekstra          Aduna BV
Knowledge Engineer      Julianaplein 14b, 3817 CS Amersfoort
http://aduna.biz        The Netherlands
tel. +31 33 46599877
Received on Wednesday, 21 December 2005 11:42:01 GMT

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