Efficient Query Routing for XML Documents Retrieval in Unstructured Peer-to-Peer Networks

In this paper, we propose an efficient query routing approach for XML documents retrieval in unstructured Peer-to-Peer networks. In our approach, when a node forwards a query specified by XPath expression(XPE), some information about matched document that this node provides is attached to the query message. Then the nearby nodes receiving the messages create an index structure based on this relevant information, termed Routing Guide(RG). With RGs, a node forwards queries only to a subset of its neighbors which are more likely to have matched documents rather than by selecting neighbors randomly or by selecting all. Simulative experiments show that our approach outperforms most search techniques currently in use(e.g. BFS and random walk) especially when the number of the queries is very large.