Content-Based Routing of Path Queries in Peer-to-Peer Systems

Abstract

Peer-to-peer (P2P) systems are gaining increasing popularity as a scalable means to share data among a large number of autonomous nodes. In this paper, we consider the case in which the nodes in a P2P system store XML documents. We propose a fully decentralized approach to the problem of routing path queries among the nodes of a P2P system based on maintaining specialized data structures, called filters that efficiently summarize the content, i.e., the documents, of one or more node. Our proposed filters, called multi-level Bloom filters, are based on extending Bloom filters so that they maintain information about the structure of the documents. In addition, we advocate building a hierarchical organization of nodes by clustering together nodes with similar content. Similarity between nodes is related to the similarity between the corresponding filters. We also present an efficient method for update propagation. Our experimental results show that multi-level Bloom filters outperform the classical Bloom filters in routing path queries. Furthermore, the content-based hierarchical grouping of nodes increases recall, that is, the number of documents that are retrieved.

Secure and Dynamic On-Demand Access to Distributed Information through Information Brokering System

“…A robust mesh is used in [8] for routing XML packets with a gab based solution for overlay networks. XPath query related routing [9] is also used in XML databases and content-based routing was also used in P2P systems. To protect data from untrusted brokering encrypting metadata is also used.…”

Path Query Routing in Unstructured Peer-to-Peer Networks

“…For instance, the problem of routing path queries in unstructured peer to peer network has been tackled by [12,9,26]. However they all consider hierarchical topologies with super-peers, which we want to avoid for the reasons stated previously.…”

“…Exponentialy Decaying Bloom Filter (EDBF) has been proposed by [15] and Multi-level Bloom Filter (MLBF) has been introduced by [12]. Both are presented later in this article.…”

Efficient Data Dissemination in Overlays

“…Allowing nodes to maintain summaries of remote peers' content enables them to guide queries to peers more likely to provide relevant answers. Bloom filters [2] are a probabilistic data structure for content summarization that has been used in peer-topeer environments [6,11,14,19]. In Planet-P [6] gossiping is used for propagating content indices across peers.…”

“…In OceanStore [19] attenuated Bloom filters are propagated to improve searching in a structured peer-to-peer network. Breadth and depth Bloom filters have also been used for summarizing hierarchical data structures such as XML documents in a hierarchically organized network [11]. In our previous work [18] we have explored strategies for disseminating Bloom filter content summaries in unstructured peerto-peer networks.…”