Schema mapping and query reformulation in peer-to-peer XML data integration system

In the paper we discuss the problem of XML data integration in a P2P environment. In this setting each peer stores schema of its local data, mappings between the schema and schemas of some other peers (peer’s partners), and schema constraints. The goal of the integration is to answer the queries formulated against arbitrarily chosen peers. The answer consists of data stored in the queried peer as well as data of its direct and indirect partners. We focus on defining and using mappings, schema constraints, and query reformulation in such scenario. We discuss a strategy that allows us to obtain a complete answer with the possibility of discovering missing values. The method is the theoretical foundation of the implementation of SixP2P system (Semantic Integration of XML data in P2P environment).