As Semantic Web continues to grow, more and more data will be expressed in uniform formats recommended by Semantic Web, such as RDF/XML or n-triples. In a pervasive environment, performing reasoning on this streaming data becomes a challenging task. Existing reasoners use techniques that load the whole RDF graph in main memory and carry out queries on it. This approach is of little use in real-time reasoning for streaming scenarios and takes considerable amount of time.

We combine the continuous query processors with Semantic Web techniques to build an "rdfs:subClassOf" reasoner that can deal with streaming data. Given an ontology, we pre-compute the transitive closure of all classes on "rdfs:subClassOf" relationship and store the class-subclass relationships in a database table. At run-time we just need to query the database to identify subclass events of the event of concern. There are already many applications which describe data in RDF compatible formats. We feed streams of such RDF data to our query processor and carry out real-time rdfs:subClassOf reasoning on them. ]]>