Rdf Query

Work on query languages began to surface within W3C in 1998 at its QL98. Subsequent developments include Rql, SquishQl and its ancestor Rdql. While Rdql has been submitted to W3C, there's no standard on an Rdf query language up to now. W3C has a more complete summary on RdfStorage and RdfQuery on its main RDF page.

Rql - developed at ICS FORTH

A GPL licensed implementation in C++ is available, running on Linux and Solaris. This requires a recent PostgreSql server.

main site: http://139.91.183.30:9090/RDF/RQL/

SesameRql developed for the Sesame project

Reimplementation of Rql, the project has BNF and a tutorial: http://www.openrdf.org/publications/rql-tutorial.html

Subsequently evolved to SeRql.

SquishQl developed at UBristol

Main site: http://swordfish.rdfweb.org/rdfquery/

An implementation in Java is available supporting in-memory and PostgreSQL (via JDBC) backends. It' licensed under the GPL compatible W3C license.

Subsequently evolved to Rdql.

Rdql developed at HP Labs Bristol

Rdql was submitted to W3C. The W3C has the official submission document and a W3C team statement. Robin Cover has comments and various resources at Cover Pages.

An implementation is provided as part of Jena.

SeRql - the new query language for the Sesame project.

Inspired by earlier work, including Rdql and Rql. Specified in chapter 6 of the `Sesame Users Guide', includes BNF (see http://www.openrdf.org/publications/users/ch06.html#d0e968 )