Research And Implementation Of An Improved P2P File Transfer System

With the development of globalization, the distribution of a lot of enterprises is more and more scattered. Because of the different network environment, the file transfers more slowly among different regions. The current popular P2 P software can improve the file transfer speed by downloading from multiple resources in the same time. However, many problems are solved in the way of single-point transfer mode, and the characteristic of multi-source transmission is ignored.The transmission interruption often appears, which affects the quality and the efficiency of the network. How to improve the method of transmission resume from the interruption in the P2 P mode is discussed in this thesis. The current method of processing breakpoint and the current method of processing suspend-resume are studied in this thesis, too. Based on the characteristic of multi-source, resume methods for the P2 P transmission mode are put forward. Based on these methods, a P2 P file transfer system with controllable speed is designed and realized. The work in this thesis can be summerized as follows:1) The main reasons of the transmission interruption in the network are analyzed. The disadvantages of the current P2 P software in the breakpoint information storage and suspend-resume are discussed in this thesis.2) A method for saving breakpoint state based on local memory relationship and a method of asymmetric competition of mutex for suspend-resume, are studied in this thesis to solve the problem of transmission resume.3) According to different environment of Linux and Windows,appropriate I/O models and concurrency mechanism are selected to transfer data in P2 P mode.4) The transmission speed of the client is controlled by the server in this system. Transfer the control right of transmission speed from the client to the server to meet the needs of speed centralized control.The system is tested at the end of this thesis. The result shows that:the P2 P mode can improve file transfer speed by using multiple resources. The server can control the client transmission speed. the method for saving breakpoint state based on local memory relationship is more quickly in the breakpoint processing. The method of asymmetric competition of mutex for suspend-resume is more efficient on the recovery from the pause state.