【正文】 he user to enter information presented to provide background on the web application form and make processing the second layer is the background Web second layer of the Web server will initiate the process to respond to this request, and dynamically generate a bunch of HTML code, the result of which is embedded processing, returned to the client the request submitted by the client includes a data access, Web server, and database server needs to plete the collaborative third layer is the database server tasks similar to C/S mode, responsible for coordinating the SQ different Web server sends requests, manage the database.Ⅱ Difference between B / S and C/S(1)Hardware environmentC/S is generally built on a dedicated network, a small range in the network environment, then provide connectivity and data exchange services between the LAN via a dedicated , the network does not have to be a dedicated hardware environment, such as telephone access, leased they the C/S stronger adaptation, generally as long as the operating systems and browsers on the line.(2)Safety requirementsRelatively fixed C/S is generally useroriented group of information security controls are highly confidential information systems using C/S structure can publish public information through B/ / S based on the wide area network, the security control is relatively weak, the user may for unknown.(3)Program StructureC/S programs can pay more attention to the process, you can check on the multilevel privileges on the system speed can be less , the need to establish more optimal higher requirements B/S structure of the application architecture is the development trend of the ratio C/S, from the Series the BizTalk 2000 Exchange 2000, a prehensive support network ponents to build a and IBM push JavaBean ponent technology, so that B/S is more mature.(4)Software reuseC/S integrity of the program can be considered unavoidable, reusable ponent reuse is not as good in B/S requirements under the , requiring relatively independent functional can be relatively like to buy a table can be reused, rather than doing a table in a stone wall(5)System MaintenanceC/S program due to the holistic, whole investigation must deal with the problems and system do a new systemB/S ponent position, replacement of individual aspects of ponents, to achieve a seamless system upgrade system maintenance overhead is from the Internet to download the installation can be upgraded.(6)Deal with the problemC/S can handle fixed user plane, and in the same area, security requirements, and operating systemrelated all be the same , for different user groups, geographic dispersion, which is theC/S can not be with minimum operating system platform.(7)User InterfaceC/S MultiWindow platform is built on the limited performance of the method, programmers generally , there are more rich a