ActOn: A Semantic Information Service for EGEE

We describe an information service that aggregates metadata available in hundreds of information sources of the EGEE Grid infrastructure. It uses an ontology-based information integration architecture (ActOn), which is suitable the highly dynamic distributed information sources available in Grid systems, where information changes frequently and where the information of distributed sources has to be aggregated in order to solve complex queries. These two challenges are addressed by a metadata cache that works with an update-on-demand policy and by an information source selection module that selects the most suitable source at a given point in time, respectively. We have evaluated the quality of this information service, and compared it with other similar services from the EGEE production testbed, with promising results