说明：  根据p2p网络的拓扑结构进行分类研究,着重针对中心化拓扑、全分布式非结构化拓扑、半分布式拓扑和全分布式拓扑4种结构及其检索机制进行概述、 综合分析和比较研究，并提出p2p系统目前面临的主要问题及其发展趋势。
(According to p2p network topology to classify research center that focuses on topology, the topology of distributed unstructured, semi-distributed topology and all four kinds of distributed topology structure and retrieval mechanisms outlined in the comprehensive analysis and comparison of research and p2p system to the main issues currently facing and its development trend.)