- From: Eric Prud'hommeaux <eric@w3.org>
- Date: Tue, 1 Jun 2004 23:23:51 +0900
- To: public-rdf-dawg@w3.org
Persuant to my action item to review RDQL with respect to the requirements [1] from the 25-May 2004 teleconference [2], I evaluated (and implemented) RDQL per the Jan 2004 W3C submission [3]. I was planning on getting this out later this week, but earlier is probably better than better. Besides, Andy will fix it all up for me. I copped Bryan's convention [4] for reporting requirement support: rdql+ : rdql supports this requirement today under a suitable protocol binding and/or query language. rdql- : the requirement appears to be explicitly outside of the scope of rdql, which is not to say that it could NOT be met by a suitable revision of rdql. rdql? : need more information to make the determination. This somewhat contrived example query will serve as a syntactic example of how RDQL meets the requirements: SELECT ?family , ?given FROM <http://example.org/JohnzVcard.rdf> WHERE (?vcard vcard:FN "John Smith") (?vcard vcard:N ?name) (?name vcard:Family ?family) (?name vcard:Given ?given) (?name vcard:age ?age) (?name vcard:shoeSize ?shoeSize) AND ?shoeSize > 5 AND ?age >= ?shoeSize USING vcard FOR <http://www.w3.org/2001/vcard-rdf/3.0#> Requirements: rdql+ : 3.1 RDF Graph Pattern Matching WHERE (?vcard vcard:FN "John Smith") (?vcard vcard:N ?name) (?name vcard:Family ?family) (?name vcard:Given ?given) rdql+ : 3.2 Variable Binding Results SELECT ?family , ?given From the spec: [[ The variable "?x" will be bound to the label of the subject resource. All such "x" are returned ]] rdql- : 3.3 Extensible Value Testing Has support for equality and comparison operators for integers. rdql- : 3.4 Subgraph Results rdql+ : 3.5 Local Queries The specification does not describe the result format or mechanism, however, an API implementation of this protocol would be able to perform local queries. rdql- : 3.6 Optional Match rdql+ : 3.7 Limited Datatype Support AND ?shoeSize > 5 AND ?age >= ?shoeSize rdql- : 3.8 Bookmarkable Queries RDQL does not spcify a canonicalization into a local part of a URI. rdql+.5 : 3.9 Bandwidth-efficient Protocol Query protocol is terse and easy on the eyes. No result protocol is defined. rdql- : 3.10 Result Limits Design Objectives: rdql+ : 4.1 Human-friendly Syntax RDQL queries read like a sentence. They allow the use of qnames. Term-enclosing parens could be replaced by a single delimiter ala N3, but I it is, in my opinion, easy on the eyes. rdql- : 4.2 Provenance rdql- : 4.3 Non-existent Triples rdql- : 4.4 User-specifiable Serialization RDQL does not specify results format/protocol nor provide syntax to select such. rdql- : 4.6 Aggregate Query rdql- : 4.6 Additional Semantic Information [1] http://www.w3.org/2001/sw/DataAccess/UseCases [2] http://www.w3.org/mid/--lost-my-copy-of-the-minutes [3] http://www.w3.org/Submission/2004/SUBM-RDQL-20040109/ [4] http://www.w3.org/mid/D24D16A6707B0A4B9EF084299CE99B39053F8C01@mcl-its-exs02.mail.saic.com -- -eric office: +1.617.258.5741 NE43-344, MIT, Cambridge, MA 02144 USA cell: +1.857.222.5741 (eric@w3.org) Feel free to forward this message to any list for any purpose other than email address distribution.
Received on Tuesday, 1 June 2004 10:24:01 UTC