Generating Mediation Queries for XML-based Data Integration Systems Bernadette Farias Loscio and Ana Carolina Salgado   View Paper (PDF)   Return to Data Integration Abstract In recent years, the problem of integrating data from heterogeneous and autonomous data sources has received a great deal of attention from the database research community. This problem consists in providing a uniform view of these data sources, called mediation schema, and defining a set of mediation queries which compute each object in the mediation schema. Data integration systems can be classified according to the approach used to define the mediation queries between the data sources and the mediation schema. The first approach is called global-as-view (GAV) and requires that each object of the mediation schema be expressed as a view on the data sources. In the other approach, called local-as-view (LAV), mediation queries are defined in an opposite way; each object in a given source is defined as a view on the mediation schema. In this paper, we propose a process to generate mediation queries for an XML-based data integration system which adopts the GAV approach. Our proposal defines a solution space which provides the set of potencial queries that compute a given element in the mediation schema. In our approach, the mediation schema is represented by a set of entities and relationships among them. Therefore, the process of mediation queries generation consists in discovering a computing expression for each entity in the mediation schema. ©2004 Association for Computing Machinery