Processing Query in P2P XML Data Sources

P2P technology provides new views for data integration purposes. In P2P systems, there is no global knowledge, neither a global schema nor information of data distribution or indices. An important issue in the context of schema-based P2P systems is efficient query processing. Because of the lack of global knowledge, query planning is much more difficult than in centralized systems. In this paper, we assume XML as the native data model for all peers, and address the problem of distributed query processing in the P2P XML data sources. We discuss strategies of query decomposition and routing based on different kinds of routing indexes. In our work, FLWR queries of XML data are translated into algebraic expressions, and are executed by relying on data-integration-like techniques. To speed up query execution and to decrease peer and super peer workload, we exploits mechanisms for replicating peer content, and for caching query plans and query results.