Retrieving arbitrary XML fragments from structured peer-to-peer networks

This paper proposes a novel method for the storage and retrieval of XML in structured P2P networks. Peer-to-Peer (P2P), a new paradigm in the field of distributed computing, is attracting much attention. In particular, DHT (Distributed Hash Table) offers effective and powerful search through peer collaboration. However, query retrieval of arbitrary XML fragments using DHTs is a challenging issue because of the impedance mismatch between hashing, which is the core mechanism of the DHTs, and the complex structure of XML data and the XML query model. To address this problem, we propose a novel scheme for managing XML data in DHT. Specifically, we (virtually) deploy two kinds of DHTs, called Contents-DHT (C-DHT) and Structure-DHT (S-DHT), to map textual information and structural information, respectively. Queries against stored XML are processed using the DHTs concurrently. We can, therefore, retrieve arbitrary XML fragments. Effectiveness of the proposed scheme is demonstrated with a series of experiments.