【摘要】 在分布式Peer-to-Peer (P2P)系统中,每个节点都具有相同的能力,负有相同的责任.它们将自己的资源提供给系统,同时可以共享系统中的信息和服务.但是,大多数P2P系统都具有局限性,比如说Napster,Gnutella,它们提供资源共享的粒度很粗糙,进一步地,它们忽略了文件在内容粒度上的共享.并且,大多数系统中节点的Peer是静态指定的,系统中不支持只具有临时IP的节点加入.提出了一个BestPeer的P2P系统,它具有以下几个特性:首先,它将移动Agent技术与P2P技术相结合,从而可以在数据提供者本地进行数据处理.其次,这个系统具有自配置的特性.一个节点可以动态地决定与哪个节点直接相连(决定哪个节点成为该节点的Peer),从而使网络结构的配置达到最优.另外,BestPeer系统提出了一个位置独立的全局名查找服务器(LIGLO).这个服务器可以惟一地识别具有动态IP地址的节点,从而使节点能够在它的Peer的IP地址发生改变后仍然能够找到它.BestPeer系统建立后,提出了一套评估系统的方法.采用32台Pentium II PC机进行实验,每台机器上都运行基于Java的存储管理程序.实验结果表明,BestPeer系统具有比传统的无自调整能力的P2P系统更好的性能.更进一步的实验还显示了BestPeer系统优于Gnutella 协议下的系统.更多还原

【Abstract】 One of the most important features for a peer-to-peer (P2P) distributed system is to share information and services among nodes with equivalent capabilities and responsibilities by pooling their resources together. Nowadays, most of the existing P2P systems such as Napster and Gnutella only provide some kinds of coarse granularity information sharing without taking account of the content of the file. And, typically nodes (peers) are defined statically. In addition, there is no mechanism to support the join of nodes with temporary network addresses. In this paper, a prototyping P2P system, BestPeer is presented. The BestPeer is unique in several ways. Firstly, it combines the power of mobile agents into P2P systems to perform operations at peers?sites. Secondly, it is self-configurable. A node can dynamically select the set of peers with which it can communicate directly based on some optimization criterion. Thirdly, the BestPeer provides a location independent global named lookup server (LIGLO) to identify peers with dynamic (or unpredictable) IP addresses. The BestPeer is evaluated on a PC cluster consisting of 32 Pentium II running Java-based storage manager. The experimental results show that the BestPeer provides excellent performance compared with traditional non-configurable models. Further experimental study reveals its superiority over Gnutella抯 protocol.更多还原