ECQ: A Simple Query Language for the Semantic Web

With the increasing development of real applications using semantic Web technologies, it is necessary to provide scalable and efficient ontology querying and reasoning systems. In this paper we present ECQ (Extended Conjunctive Queries), a simple but powerful query language for OWL. ECQ supports Tbox reasoning and complex queries, going beyond conjunctive queries, which are needed for real semantic Web applications. The syntax of ECQ is the same as other description logic languages, making it easy to use for this community of researchers. We also present an implementation of the language over a scalable and persistent OWL reasoner, that is called DBOWL. Therefore, queries can use Abox reasoning to obtain more complete results.