4th Generation Flexible Query Language for Ontology Querying

Ontology has emerged as one of the rapidly growing method for meaningful knowledge representation. Realizing the potential of Semantic Web, Web Ontology Language (OWL) has provided a standard notation for creating Ontologies, while SWRL has provided the notation for defining rules to build new knowledge bases for the web applications. However, need for an efficient query Language for Ontologies is still unaddressed. In this paper we present ROQL, a Rule-based Ontology Query Language for creation and querying Ontologies based on the semantics of OWL 2.0 and syntax of SQL and SPARQL. With ROQL we provide abstract syntax to work with Ontologies. Compared with off-the-shelf query languages, we offer the support for creating, updating, and selecting knowledge from Ontology based knowledge bases with considerably more efficiently and flexibly. In addition to the clear and easy syntax, ROQL provides the possibility for defining rules in queries while selecting and inferring knowledge.