Semantic Caching in Ontology-based Mediator Systems

The integration of heterogenous web sources is still a big challenge. One approach to deal with integration problems is the usage of domain knowledge in form of vocabularies or ontologies during the integration (mapping of source data) as well as during query processing. However, such an ontology-based mediator system still have to overcome performance issues because of high communication costs to the local sources. Therefore, a global cache can reduce the response time significantly. In this work we describe the semantic cache of the ontology-based mediator system YACOB. In this approach the cache entries are organized by semantic regions and the cache itself is tightly coupled with the ontology on the concept level. Furthermore, the cache-based query processing is shown as well as the advantages of the global concept schema in the creation of complementary queries.