Based On P2p File Sharing System Design And Implementation

With the development of the modern information technology, the current instant messaging services enable people to know each other's existence and to exchange information with each other. However, almost all of these services are based on client / server (C / S) architecture. If the server fails, all connections will be lost. Thus, in order to improve the situation, peer-to-peer (P2P) network architecture has emerged. In P2P network architecture, each peer node (peer) plays both the role of a server and a role of a client. And P2P network has implemented the transmission and sharing of resources among peer nodes. The greatest significance of P2P technology lies in the form of resource Discovery Lookup of self-organized, peered coordinated nodes at the edge of the network.P2P technology has the characteristics of decentralization, scalability, robustness, high performance / price ratio, broader prospects for applications, and so on. Currently the technology is constantly applied to the areas of military, business, government information. Additionally, IT companies like SUN, Google and Microsoft are doing extensive research on this technology.This thesis firstly introduces the basic theory of P2P technology, the status of P2P file-sharing system, and by analyzing the P2P network topology, finds the type of the structure which is suitable for the system; and problems faced by file-sharing system are pointed out by analyzing the existing file-sharing system. System design requirements and model frame of file-sharing system in the model design of P2P network file sharing system are proposed, meanwhile, features and services of various layers are illustrated. Secondly, the main components in P2P file-sharing system as well as their roles and functions in the file-sharing system are put forward. Further, based on the understanding of P2P technology, the thesis has mainly elaborated the development requirements of the file-sharing system and provided the system's overall design flow chart and design class diagram of the server and the client. At last, the system has been implemented by programming and each module functionality between the server-side and client-side and the interoperability among modules have been achieved: Server-side and client-side can communicate normally, users can complete the log in, check out the information, log out and other operations, and file uploading and downloading operations can be implemented between peers.