A Distributed Case-Based Query Rewriting

In literature, the mediator architecture has been proposed for taking information from distributed, heterogeneous, and often dynamic sources and making them work together as a whole. In this paper we propose a distributed case-based approach for the main problem of a mediator, i.e. rewriting queries according to mediator’s schema. According to this approach we use a case memory as mediator’s schema. Therefore, such a schema is not static (as in other systems) but is dynamically updated through the cooperation with information sources and other mediators, strongly influenced by the queries submitted by a consumer. From the analysis of different cooperation strategies arises that it is more efficient and effective for a mediator to directly cooperate with information sources, when the sources are few. Otherwise, it is more efficient to cooperate with other mediators.