We present a framework for creating schema mappings between independently developed schemas. In our approach, attribute correspondences (the result of "schema matching") are translated into a set of mappings that capture the semantics of the source and target schemas (including their hierarchical organization as well as referential constraints). These mappings are then translated into queries over the source schema(s) that produce a target instance satisfying the referential constraints and structure of the target schema. These queries preserve the semantic relationships of the source and target schemas. We present both the mapping generation algorith, and the data translation algorithm of Clio. We present our experience using Clio to create mappings among relational and XML schemas. The mappings produced by Clio can be used both within data integration where source data is queried through a virtual (mediated) target view and for data exchange. Clio was a joint research project between the University of Toronto and IBM Almaden Research Center begun by Laura Haas and Renée Miller. Clio technology has been transferred into IBM's Rational Data Architect product line.
