- From: Phil Dawes <pdawes@users.sourceforge.net>
- Date: Thu, 6 May 2004 10:16:35 +0100
- To: www-rdf-interest@w3.org
- Cc: andy.seaborne@hp.com
Hi All, I am currently writing wrapper code around Sesame[2] and RAP[3] to give them web interfaces corresponding to the Joseki webapi[4]. The point of the exercise is to be able to write web client code that is store agnostic. Unfortunately there seem to be some incompatible variances in the way RDQL is implemented in the different RDF stores. For example, the W3C submission spec[1] (which was written after a lot of the implementations) says that qnames in 'where' clause triplepatterns are not surrounded by '<' and '>'. E.g. (example taken out of the W3C submission[1]) (works with Jena/Joseki but not RAP or Sesame) SELECT ?family , ?given WHERE (?vcard vcard:FN "John Smith") (?vcard vcard:N ?name) (?name vcard:Family ?family) (?name vcard:Given ?given) USING vcard FOR <http://www.w3.org/2001/vcard-rdf/3.0#> Unfortunately both Sesame(1.0) and RAP(0.71) require '<' and '>' around qnames for the query to parse. E.g. (works with Jena and RAP, but not Sesame and isn't spec compliant) SELECT ?family , ?given WHERE (?vcard <vcard:FN> "John Smith") (?vcard <vcard:N> ?name) (?name <vcard:Family> ?family) (?name <vcard:Given> ?given) USING vcard FOR <http://www.w3.org/2001/vcard-rdf/3.0#> Also, Sesame requires commas between each triplepattern clause and between the triplepatterns themselves, RAP doesn't, and the spec says they're optional. E.g. (works with Jena, RAP and Sesame, but isn't spec compliant) SELECT ?family , ?given WHERE (?vcard, <vcard:FN>, "John Smith"), (?vcard, <vcard:N>, ?name), (?name, <vcard:Family>, ?family), (?name, <vcard:Given>, ?given) USING vcard FOR <http://www.w3.org/2001/vcard-rdf/3.0#> So unfortunately writing an RDQL query that works with all three stores involves being incompatible with the spec! So the question is, should I be lobbying/helping the store vendors to fix the RDQL implementations WRT the W3C Submission (breaking existing client RDQL code in the process), or does the W3C submission need changing to match the implementations in the stores? Is there enough existing client RDQL code to be worrying about this? (we have 5 applications at work which would need changing, but the changes are trivial) Many thanks, Phil [1] http://www.w3.org/Submission/2004/SUBM-RDQL-20040109/ [2] http://www.openrdf.org/ [3] http://www.wiwiss.fu-berlin.de/suhl/bizer/rdfapi/ [4] http://www.joseki.org/
Received on Thursday, 6 May 2004 05:46:16 UTC