Institute for Informatics
Georg-August-Universität Göttingen

Databases and Information Systems

Uni Göttingen

OWLQ: A language and ontology for stating conjunctive queries against OWL data

OWLQ provides an ontology of queries. A query consists of class definitions (in OWL), definition of variables ranging over these, definition of variables depending on them, and constraints between these variables. Individual classes and predicates can optionally be considered under closed-world-semantics. Thus, an OWL query is a graph that describes a conjunctive query. OWLQ queries can be evaluated -obviously-, but also analyzed based on the above notions for satisfiability and containment. The prototype implementation consists of a Jena-based core with a plugged-in DL Reasoner (Pellet).

OWLQ is used for Queries, tests, and event matching in MARS: prototype
. (click on "Register XML Rule" and have a look)

An online interface to the prototype can be found at Note that it may sometimes be down.

The work is described in the MSc Thesis by Jochen Kemnade: OWLQ - An OWL-based Query Language for OWL Data.