The Research And Application Of Proxy Model Based On Network

Along with the development of computer network technology and prevalence of wide band, it is ISP vendor's impending demand to develop high performance and flexibility proxy server. Proxy technology is a remarkable embranchment of computer technology.Proxy server is a network node that accepts or explains the connection requests of clients and connects the target server. It has been widely applied to the design of application layer gateway model and the research of firewall technology. Proxy technology is very crucial in the Internet sharing solution.This thesis introduces TCP/IP hierarchical theory of Internet and the realization and application of every layer proxy technology. Since the application layer proxy is very flexible and can be applied to all kinds of applications, it absorbed many developers. How to improve the reliability and expandability without losing in performance is a big difficulty in developing application layer proxy server, so it is necessary to find out a new application layer proxy model for solving the above problems.IOCP (I/O Completion Port) is a mechanism of Windows 2000 that can use and manage multi-thread rationally. With completion port, it can use certain threads to deal with overlapped I/O operations. IOCP can help the proxy server to deal with a great deal of request of multi-clients. It is advantageous for IOCP to develop application such as proxy server and so on. It can make the performance of the system in a better state.Based on analysis and research of Windows 2000 IOCP mechanism and application layer protocol, this thesis brings forward a virtual C/S application layer proxy model base on IOCP mechanism. Using the IOCP provided by kernel of Windows 2000, this model presents a universal application layer proxy method and solves the problem of multi-thread competition in proxy model preferably, which improves the performance and expandability of single proxy server and provides thefoundation for realization of virtual server using cluster technology under distributedenvironment.Finally, the thesis combined the model with practice application organically, and developed successfully certain wireless wide-band billing gateway. This thesis explains the running mechanism of HTTP, FTP, SMTP, POP 3 etc. and the realization of the proxy module in detail. Furthermore, it introduces concisely the algorithms of users authentication module and counting module.