- From: Mischa Tuffield <mischa.tuffield@garlik.com>
- Date: Tue, 19 Apr 2011 12:07:49 +0100
- To: public-rdf-wg Group WG <public-rdf-wg@w3.org>
- Cc: Andy Seaborne <andy.seaborne@epimorphics.com>
- Message-Id: <6586B77B-FDD1-44F2-9CB5-EBA68DBB09BD@garlik.com>
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. > > If there is to be a syntax form for a different notion, then keep them apart (based on graph literals a la N3?). > >> We should be able to queries such as "when did foaf:givenName change >> from Unstable status" or "when did DCMI begin to mention dc:audience >> ?". If we use the URI we 'GET'd for the graph name, these sort of >> historically minded queries won't be possible as the graphs will get >> mixed up. >> >> All this talk of HTTP response codes is great and nice and practical, >> ... so long as we're crystal clear that the Web gives back different >> things over time, and often we'll want to be explicit about that. >> Eventually we'll also want to be a bit more clear about security >> properties, such as which copies of a schema check out as having been >> signed by such-and-so key. >> >> cheers, >> >> Dan >> >> ps. for the foaf case, revisions are available via: svn log >> http://svn.foaf-project.org/foaf/trunk/xmlns.com/htdocs/foaf/0.1/index.rdf >> ...then you can pull them (per directory) eg. with: svn co -r r186 >> http://svn.foaf-project.org/foaf/trunk/xmlns.com/htdocs/foaf/0.1/ ... >> so you can see that >> <http://xmlns.com/foaf/0.1/homepage> >> <http://www.w3.org/2000/01/rdf-schema#domain> >> <http://xmlns.com/foaf/0.1/Person> . >> ...used to be in there, before we broadened it. Question to my mind >> is, how do we elevate the tooling so you can find this out using >> SPARQL and RDF instead of SVN and grep? >> > ___________________________________ Mischa Tuffield PhD Email: mischa.tuffield@garlik.com Homepage - http://mmt.me.uk/ +44(0)208 439 8200 http://www.garlik.com/ Registered in England and Wales 535 7233 VAT # 849 0517 11 Registered office: Thames House, Portsmouth Road, Esher, Surrey, KT10 9AD
Received on Tuesday, 19 April 2011 11:08:21 UTC