Incremental Query Answering over Dynamic Contextual Information

Context awareness is one of the key requirements for realizing the vision of ubiquitous computing. Formal representation of context information is gaining an ever increasing number of advocates. Using the Web Ontology Language (OWL) is one of the well-established practices in this regard. Nevertheless, traditional OWL reasoning and thus query answering methods are not optimized for fast changes in context data. In this paper, we present an incremental query answering method for OWL based contextual information. Our approach consists of translating the ontology schema as well as queries into rules. These rules are then used to build the Rete network which incrementally maintains the query results as changes occur in the context data. We further employ a heuristic to adaptively prune the rules which do not affect the query results. Our incremental query answering approach requires no change in existing implementations and the empirical results suggest its practicality.