Evolution of XML-based mediation queries in a data integration system

One of the main challenges in data integration systems is the maintenance of the mappings between the mediation schema and the source schemas. In a dynamic environment, such mappings must be flexible enough in order to accommodate new data sources and new users' requirements. In this context, we address a novel and complex problem that consists in propagating a change event occurring at the source level or at the user level into the mediation level. We propose an incremental approach to develop the mediation schema and the mediation queries based on the evolution of the data source schemas and the evolution of the users' requirements. The proposed approach allows the mediation level to evolve incrementally and modifications can be handled easier increasing the system flexibility and scalability.