In this paper we present a system for data integration on the web, where an XML-based mediator plays a key role providing a homogeneous view of different data sources. One novelty of our approach is that we also propose solutions for the problems of generation and maintenance of mediators. Observe that, in dynamic environments, such as the Web, individual data sources may change not only their data but also their schemas. As a result, whenever a local schema changes, the mediator needs to be updated to reflect the modifications. The proposed system uses agents to support mediator generation and maintenance. We specify a set of tasks that must be performed in order to support both generation and maintenance of mediators. In our approach, we use correspondence assertions for specifying the semantics of XML-based mediators.
Mediation system; mediation queries; data integration; XML; maintenance of mediators
