- From: Benjamin Nowack <bnowack@appmosphere.com>
- Date: Thu, 13 Jan 2005 19:39:44 +0100
- To: public-rdf-dawg-comments@w3.org
Hi, I was wondering if DAWG considered extension possibilities for quad, quintuple, 6-tuple, etc stores to make it possible to offer support for special flags or triple attributes without having to use a non-recommended query language. I know that RDF is a triple model, but I saw that SOURCE is part of the current SPARQL draft. SOURCE is a nice (and practial) extension, but reflects only one of the potential needs of an RDF store. I'd for example like to use custo triple stores tailored to the capabilities of my tools. This may be stores which have "creatorId", "lastModified", or "addedDate" attributes, or a "probablySpam" flag. These extensions are clearly not worth to be part of a standardized QL, but may be needed (or at least handy) for specific applications. Wouldn't it make sense to generalize the mechanism used for SOURCE to allow implementors of extended rdf stores to still use SPARQL? Hm, I could probably simply use FROM to implement this functionality (e.g. by using "true (?s ?p ?o)" as a parameter value: [[[ ... FROM <http://foo.com/q?probablySpam=true%20%28%3Fs%20%3Fp%20%3Fo%29> ... ]]] ) but can the querying client be sure that NULL-bindings will return an empty result? And a more standardized solution for additional restrictions would be nicer, e.g. something along [[[ ... SELECT ?s ?p ?o WHERE ( ?s rdf:type foaf:Person ) ( ?s ex:ppd ?ppd ) ( ?ppd rdf:type foaf:PersonalProfileDocument ) ( ?ppd foaf:primaryTopic ?s ) RESTR SOURCE <http://trustMe.com/ppdDump> (?s ex:ppd ?ppd) RESTR SOURCE ?ppd (?s ?p ?o) RESTR addedDate "2004-01-13" ( ?s ?p ?o ) ]]] could allow me to find all personal information "added today" of people whose personal profile documents were verified by the trustMe.com service, e.g. in order to update a local contact management tool on a daily basis. (sorry for wrong use of sparql, only just started working with it) (hm, the semweb idea would then probably lead to the use of URIs for extended restrictions, such as dawg:SOURCE or foo:addedDate..) just some thoughts, don't want to hold you up... regards, benjamin P.S.: In section "9: Querying the Origin of Statements" in the SPARQL WD [1], the foaf:PersonalProfileDocument class is used as a predicate. (A property equivalent to the ex:ppd I'm using above does not exist in foaf (yet), foaf currently uses the foaf:primaryTopic property to link the PPD to the description of the person.) [1] http://www.w3.org/TR/rdf-sparql-query -- Benjamin Nowack appmosphere web applications Kruppstr. 100 45145 Essen, Germany http://www.appmosphere.com/
Received on Thursday, 13 January 2005 18:40:24 UTC