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Re: ISSUE-30: How does SPARQL's notion of RDF dataset relate our notion of multiple graphs?

From: Nathan <nathan@webr3.org>
Date: Tue, 19 Apr 2011 12:11:24 +0100
Message-ID: <4DAD6DDC.3050900@webr3.org>
To: Mischa Tuffield <mischa.tuffield@garlik.com>
CC: public-rdf-wg Group WG <public-rdf-wg@w3.org>, Andy Seaborne <andy.seaborne@epimorphics.com>
Mischa Tuffield wrote:
> Hi All, 
> 
> <snip/>
> 
> On 18 Apr 2011, at 20:08, Andy Seaborne wrote:
> 
>> Dan,
>>
>> Good example.
>>
>> There are various ways the SPARQL dataset notion can be used.  IRI for each g-snap of the same g-box is certainly one of them.
>>
>> The whole concept of RDF datasets was a recognition that quad usage existed.  "RDF dataset" is a compromise from various existing practices, from systems using the word "context" (usually collection of triples as subset of the graph) to multi-graph usages as you describe and variations in between.
>>
>> On 18/04/11 15:27, Dan Brickley wrote:
>>> [snip]
>>>
>>> Let me offer a practical use case: the evolving RDF graphs served from
>>> FOAF and Dublin Core namespace URIs.
>>>
>>> For the FOAF case xmlns="http://xmlns.com/foaf/0.1/", the RDF
>>> available (via conneg, link rel or sometimes embedded in HTML) can be
>>> found in our Subversion server at
>>> http://svn.foaf-project.org/foaf/trunk/xmlns.com/htdocs/foaf/0.1/index.rdf
>>> ... you can fetch any version going back to ~2002 via public SVN.
>>>
>>> For the Dublin Core case, xmlns="http://purl.org/dc/elements/1.1/" and
>>> others nearby are documented in http://dublincore.org/schemas/rdfs/
>>> including links to each version of the schema file, and with
>>> social/process documentation of those changes at
>>> http://dublincore.org/usage/terms/history/
>>>
>>> Consider a SPARQL service devoted to keeping record of what key
>>> namespaces have said about themselves over the years. They could take
>>> each of these snapshot RDF files and put the corresponding triples in
>>> a different named graph. (Maybe we should prepare N-Quads/Trig dumps
>>> of the data for testing?).
>> and reserve the N-Quads and Trig as a syntax for RDF datasets.
> 
> +1 to this.
> 
> I find it important that the quad based serialisations are kept separate from the various triple-based RDF syntaxes . Ideally, the RDF will continue talking about triples (i.e. a minimum amount of change to the RDF Semantics), and the quad based serialisation will be standardised in order to allow interoperability between SPARQL stores. 

Couldn't have expressed that better myself, +1
Received on Tuesday, 19 April 2011 11:12:12 GMT

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