Maintaining Integrity Constraints among Distributed Ontologies

The data of Semantic Web exist in machine readable format called RDF, in order to promote data exchange on the web based on their semantics. As an expressive knowledge representation language for the Semantic Web, Web Ontology Language (OWL) plays an important role in modeling information in a semantic way. However, due to the nature of knowledge bases, ontologies tend to be very large, distributed, and interconnected. Thus, maintaining constraints and enforcing data consistency for a group of ontologies become very challenging. In addition, frequent updates on ontologies necessitate an automatic approach to checking for potential constraint violations before any change takes place. In this study, we conducted a pioneer study and presented a framework for checking global constraints and ensuring integrity on data that span multiple ontologies. As an update is issued to a single site, global constraints that can be potentially violated are broken down into sub constraints that only involve a very small subset of ontologies. The checking of sub-constraints runs effectively in parallel and returns results about each subset. The collection of these results determines the violation of global constraints.