Resource Positioning Algorithm. MP2P Environment

Although there is no uniform definition of P2P (in fact, almost every P2P research group has their own P2P definition), the development of P2P is well known. From the mp3 sharing system, Napster, appeared in 1999, to the popular download software, BT; from the SETI@home project supported by NASA to JXTA, the famous P2P platform proposed by SUN company; from the simple file-sharing software, Gnutella, to KaZaA, the development of P2P is very impressive. Until now, there have appeared more than 40 famous P2P systems, which deal with resource sharing, cooperate computing, instant message and system security. And more new P2P systems are emerging. Millions of users resort to P2P resource sharing systems to share their data resources. Undoubtedly, P2P has become an important distributed system and has a promising future. On the other hand, mobile wireless computing is developing rapidly. Cell phone owns more and more users, and it is getting more powerful than ever. Other mobile devices, such as PDA and Pocke PC, are also becoming more popular with the development of all kinds of wireless technologies, such as GSM, CDMA, Bluetooth and 802.11.With the advance in mobile wireless communication technology and the increasing number of mobile users, P2P computing, in both academic research and industrial development, has recently begun to extend its scope to address problems relevant to mobile devices and wireless networks. As a result, here comes a new research area, Mobile P2P (MP2P). The special characteristics of mobile environments, such as highly dynamic environment, limited bandwidth, unreliable connection and constrains of mobile devices bring new challenges for researches in MP2P. Now, MP2P researches focus on architecture and platforms, routing protocols, resource locating, peer access and control, data exchange and rendering techniques, secure communication protocols, messaging systems and broadband wireless communications. Resource locating is a key problem, since an efficient resource locating method is necessary for a MP2P system. This paper is about resource locating protocol in MP2P systems. We discuss three classic P2P resource locating methods, centralized directory model, flooded requests model and document routing model, with the help of three application systems, Napster, Gnutella and Freenet. Based on these discussions, we propose a new resource locating method, Dynamic Indices, in MP2P systems. It is an improvement of floolded requests protocol and local index protocol according to the characteristics of MP2P systems, in which every node maintains an index of nearby resources, and the scopes of these indices could change with the context. On the premise of correctness, indices provide resource location information as more as possible. The location information could shorten resource locating time and save bandwidth. The theorical analysis and our simulations have shown the advantages of our Dynamic Indices methods.