Design And Implementation Of FTP Client And Server System

With the rapid development of Internet technology, the time of information sharing has come. There are many ways of the data transmission and information sharing. FTP is undoubtedly the most widely used way among them. FTP protocol is an application layer protocol of computer network, which provides the reliable file transfer and the cross-platform feature.Two different types of operating systems can transfer files to each other as long as the FTP file transfer protocol can work on them. FTP has been widely used, but there are few free or open source FTP tools on the market. In addition, there are few domestic outstanding FTP tools. Therefore, the goal of this project is to design and implement a FTP client and server system which contains most of the functions of commercial FTP system.Firstly, the basic structure of a computer network, FTP working model and standard FTP commands and responses are studied in this thesis. The design of FTP system involves network communication technology, so this thesis introduces Windows multi-threaded network programming technology and then focuses on the concrete implementation of the FTP client and server afterwards. The entire file transfer system development is based on the Windows platform and Visual Studio development environment. The client part uses two recursive algorithms to achieve goals of uploading and downloading directories and solves the problem of transporting directories while FTP protocol can’t support it. To implement the instant display of file transfer status by designing the timer thread and statistical state thread. The server part uses multi-threading technology to solve a problem of server overload which caused by large number of concurrent users’ server and provides relatively perfect functions such as the log show, accounts management and statistics of connection status and files transmission. Besides, the server actualizes a function of resuming broken transfer while most of FTP servers don’t support it.Finally, the function and performance test proves that file transfer system designed in this thesis has a good performance and has achieved the desired design goals.