Figure 3
Ontology-Base Mediator Architecture. The mediator is composed of: a Controller (which controls the data flow in the system; a Query Planner in charge of finding a way of solving user queries using the Semantic Directory; a Query Plan Solver that executes the query plan making the corresponding calls to the data services; and an Integrator which integrates all the data retrieved from the data services to provide the user with the results of his/her query.