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Re: Indicating bNodes in XML result sets

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Fri, 26 Nov 2004 11:46:39 +0000
To: "Seaborne, Andy" <andy.seaborne@hp.com>
Cc: 'RDF Data Access Working Group' <public-rdf-dawg@w3.org>
Message-ID: <20041126114639.07e3bfeb.dave.beckett@bristol.ac.uk>

On Thu, 11 Nov 2004 11:49:53 +0000, "Seaborne, Andy" <andy.seaborne@hp.com> wrote:

> 
> In http://lists.w3.org/Archives/Public/public-rdf-dawg/2004JulSep/0556
> Dave indicated his preference for the XML form of the result set to look like:
> http://lists.w3.org/Archives/Public/public-rdf-dawg/2004JulSep/att-0556/result1.xml
> 
> This may have been covered but, if so, I have forgotten - what happnes 
> about bNodes in results?
> 
> If we have the query:
> 
> SELECT ?x ?name WHERE (?x rdf:type foaf:Person) (?x foaf:name ?name)
> 
> then there are distinct solutions for ?x with bNodes.  This should be 
> indicated in the results - this is not letting bNodes out of the graph, it 
> just allows the app to see distinguish between bNodes, or see they are the 
> same, within the result set.
> 
> I suggest having document-scoped ids (c.f. RDF/XML) that indicate there 
> were bNodes.  This means that each unique result is still unique.  Such an 
> id is not related to the internal bNode labels in the data graph.

That seems the best way to handle it.


> So we might have two 'name's being the same:
> 
> <results>
>    <result>
>      <x node="foo">
>      <name>Fido</name>
>    </result>
>    <result>
>      <x node="bar">
>      <name>Fido</name>
>     </result>
> </results>
> 
> (I don't care much about the attribute name - rdf:ID?)

nodeID maybe


> The RDF form of the result sets can do this by using bNodes in the cretaed 
> graph (and they are unlinked from the original bNodews in the data graph).
> 
> If an app wants to find a bNode again, it needs to retrive enough defining 
> properties.

yeah.

Does this have a more general non-syntax related issue that should be
pointed out - bnodes in results (any format - bindings, constructed
graphs) may/will/should have labels related to the bnode labels the
data graphs.

Dave
Received on Friday, 26 November 2004 11:54:04 GMT

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