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Re: [Graphs] Proposal: RDF Datasets

From: Yves Raimond <Yves.Raimond@bbc.co.uk>
Date: Mon, 22 Aug 2011 16:36:43 +0100
To: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>
Cc: Richard Cyganiak <richard@cyganiak.de>, RDF Working Group WG <public-rdf-wg@w3.org>
Message-ID: <20110822153643.GE24767@dvbstreamer.national.core.bbc.co.uk>
Hello!

> As I promissed to Richard during the last TC, I'm reactivating the
> thread on his proposal to "lift" the definition of RDF datasets into
> from SPARQL to RDF concepts [1]
> 
> My main concern with this proposal is that it defines a somewhat complex
> structure (the dataset) as a primitive concept in RDF. My gut feeling is
> that we could instead define more basic concepts, on top of which SPARQL
> datasets, SPARQL graph stores, and possibly other structures, could be
> defined. In my understanding, this is what the g-* terminology was
> aiming at.
> 
> In this perspective, back in June, I made an alternate proposal [2] for
> which I got almost no feedback. In a nutshell, it provides a minimal
> vocabulary for reifying RDF graphs into standard RDF, and sketches the
> semantics of such a reification. From there, it illustrates how
> multi-graphs syntaxes (such as Trig) and models (such as SPARQL
> datasets) can be defined on top of it.
> 

One concern I have with that proposal is that instructions modifying the parsing behavior are embedded within certain URIs (rdf:xml-serialization). Does that mean, when writing an RDF parser, you'd need to manually check for those specific predicates (which would need to be added as soon as there's a new serialisation for RDF ; rdf:jsonld-serialization, rdf:binaryrdf-serialization, rdf:ntriples-utf8-serialization...).

Also, the relationship between the holding graphs and the contained graphs would need to be specified exactly - are the prefixes and the base URI shared?

On a different note, it might be very difficult to read if you have a graph g quoting a graph g2 quoting a graph g3?

Best,
y

> I know that Richard was concerned about several multi-graph models had
> slight differences (e.g. can a BNode be used as a graph name), and his
> solution was to endorse one of them and wait for the others to converge.
> My proposal is rather to provide the building blocks for everyone to
> describe their model in RDF itself, and leave it open for different
> models to coexist, which is ok as long as they can all be expressed in
> plain RDF.
> 
>   pa
> 
> 
> [1] http://www.w3.org/2011/rdf-wg/wiki/TF-Graphs/RDF-Datasets-Proposal
> [2] http://www.w3.org/2011/rdf-wg/wiki/TF-Graphs/RDF-Quadless-Proposal
> 
Received on Monday, 22 August 2011 15:37:21 GMT

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