In this paper, we present iBroker, an Intelligent Broker for ontology based publish/subscribe systems which syntactically and semantically match incoming OWL data to multiple user profiles. iBroker effectively manages user profiles based on the semantics of query patterns in user profiles formulated in SPARQL. iBroker uses a semantic matching algorithm to efficiently process OWL data and generate the complete results for user profiles, considering the core semantics of OWL. Experimental results demonstrate that iBroker is more efficient and scalable compared to an existing broker for ontology based publish/subscribe systems.