- From: Alberto Reggiori <alberto@asemantics.com>
- Date: Tue, 25 Jan 2005 15:50:48 +0100
- To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
hi all, while doing a walk-through the grammar in the current editor draft [1] I found that we allow nested SOURCE patterns - these are two productions relative to it: [6] SourceGraphPattern ::= 'source' '*' PatternElement | 'source' VarOrURI PatternElement [10] PatternElement ::= TriplePattern | GroupGraphPattern | SourceGraphPattern | OptionalGraphPattern | 'and'? Expression which legally allow to write queries like (note the nesting of SOURCE) PREFIX data: <http://example.org/foaf/> PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?mbox ?age ?ppd GRAPH data:aliceFoaf data:bobFoaf GRAPH data:peterPanFoaf #this is being nested WHERE SOURCE data:aliceFoaf { ( ?alice foaf:mbox <mailto:alice@work.example> ) ( ?alice foaf:knows ?whom ) ( ?whom foaf:mbox ?mbox ) ( ?whom PersonalProfileDocument ?ppd ) # nested SOURCE SOURCE data:peterPanFoaf { ( ?peter foaf:mbox <mailto:peter_pan@not-working.example> ) ( ?peter foaf:knows ?peter_whom ) ( ?peter_whom foaf:mbox ?mbox ) ( ?peter_whom PersonalProfileDocument ?ppd ) } } SOURCE ?ppd { ( ?w foaf:mbox ?mbox ) ( ?w foaf:age ?age ) } Even if syntactically correct, it could make hard to the reader being convinced that such a query makes sense in the real world - by trying to follow the current editor's draft design it seems we have two nested "trusted graphs" (??). Anyway, I find nesting of SOURCEs useful at some stage, but hard to fit in our design - also the GRAPH/LOAD design discussing at the face-to-face is less clearer when nesting is faced.... Does this make sense to you ? Is the design meant to cover this part? cheers Alberto [1] http://www.w3.org/2001/sw/DataAccess/rq23/ - Alberto Reggiori, Senior Partner, R&D @Semantics S.R.L. www.asemantics.com Milan Office
Received on Tuesday, 25 January 2005 14:50:51 UTC