语义对等覆盖网中社区结构的发现和评价

最近,通过建立语义覆盖网络来提高大规模分布式网络环境中信息检索服务的性能成为对等计算领域的研究热点.目前,研究者们在语义覆盖协议和搜索算法方面已经做了大量研究,证明了语义覆盖在基于对等网络模型的内容定位应用方面极为有效.然而,分析和评价语义覆盖网络特征的研究工作确非常有限.文中通过建立数学模型和设计启发式回溯-贪婪混合算法、确认了语义覆盖网络的一种主要内在特性——社区结构特性.利用评价模型比较了SemreX语义覆盖网络和Gnutella网络的性能,实验结果显示SemreX覆盖网具有显著的社区结构特征,而Gnutella网络却没有这样的特征.另外,通过分别在两种覆盖网中仿真洪泛协议发现具有显著社区结构特征的覆盖网在内容定位方面效率更高.

Finding and evaluating the community structure in semantic peer-to-peer overlay networks

Recently much attention has been paid to semantic overlay networks for information retrieval in large scale peer-to-peer networks, and much research work on semantic overlay protocols and searching algorithms has been done and the results indicate that semantic overlay is effcient for content searching in peer-to-peer networks. However, very limited work has been done to analyze and evaluate the characteristics of semantic overlay networks. In this paper we identify a natural property of semantic overlay networks, the community structure. We propose a mathematical model to evaluate the property of community structure of semantic P2P overlay networks. A heuristic algorithm is designed to optimize the community structure. Using the evaluation model we compare the SemreX semantic overlay with the Gnutella network. Results demonstrate that a SemreX overlay network has the distinctive community structure feature, while a Gnutella-like network does not. We also simulate a simple fooding protocol in both overlays to show that the overlay with community structure is more effcient for content searching.