- From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
- Date: Mon, 17 Jan 2005 10:25:56 +0000
- To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
On Sun, Jan 16, 2005 at 04:42:59 +0000, Andy Seaborne wrote: > >Great, but whats the purpose of the FROM and GRAPH keywords here? Are they > >to illustrate something I'm missing, or are they neccesary? > > Illustrating. Quoting from earlier: "Use of FROM or GRAPH is optional" > > My command line apps can't construct arbitrary RDF datasets from command > line arguments yet. The manifest form can't describe them either. They > can be specified in queries themselves. Putting then in was just to make > the point and avoided writing a (small) custom program when the computer > could already do it. OK, I'm missing something, I'l reread the relvent section and see if I can find what I missed. > >Also, if you read in a graph that has: > > > ><owl:Ontology rdf:about=""> > > ... > ></owl:Ontology> > > > >Does the ... get assertad with urn:x-local:foo, or the resolved URI as its > >subject? > > The URI where the graph was read from - the external one - the http:// in > the above. rdf:about="" is just shorthand and the relative URI resolution > rules apply before local handling. OK, 3store currently uses the internal one, but theres no good reason for that. > An alternative modelling would be to have internal URIs to represent the > event of reading the remote graph: > > <urn:x-local:graph1> > :read "2005-01-16T03:8:03Z" ; > :readFrom <http://example.org/foaf/graph> ; > :size 23563 ; > :processingApplied :rdfsRuleSet ; > :cause <dailyUpdate> . > > > (the test case is a slight cheat - it isn't clear what the dc:date > refers to but it is an "event of interest", but you can't have another date > now without confusion). Right, for this reason I assert an event instance, something link: <urn:x-local:graph1> :last-updated _:3; :updated _:3; :updated _:2; :updated _:1. _:3 dc:date "2005-01-17T10:19:00Z" ; ... But I dont see the need to standardise this housekeeping, at least not yet. I dont feel that I've refined it enough myself. > ---- Keywords: > > The use of the word "SOURCE" is a bit weak. GRAPH would have been clearer > and in a clearing out of the grammar, maybe using GRAPH for SOURCE (as GRAPH > is a valuable keyword). I dont mind either way, but I think someone had a reason not to use GRAPH for thats currently SOURCE at the bristol ftf. > FROM is SQL heritage back from rdfdb has: > """ > select [variable1, variable2, ... ... ] from {database} > """ > > So: > > s/GRAPH/USE/ > s/SOURCE/GRAPH/ > > any suggestions for specifying the unnamed graph (currently FROM) and named > graphs (currently GRAPH) would be very welcome. > > I'd also like the FROM/USE (current FROM/GRAPH) to come before the SELECT. > With PREFIX etc first, it seems more natural to me to have all setup first. Agreed. - Steve
Received on Monday, 17 January 2005 10:25:58 UTC