The Study On The Method Of Three-tier Structure And Its Application

Through research on materials and application, we can come to a conclusion that two-tier c/s structure mode already out of date, because it has two original problems, one is complex on setup, the other is that cannot be used by a large number of users. Two-tier b/s mode also cannot satisfy the user's need for its simple structure, low security and lack of database. In order to change the disadvantages of two-tier structure mode, the three-tier structure mode was given. Three-tier c/s structure mode already resolve most of the problems of two tier c/s structure, and can be used by large users, high stability, but the client tier and application tier must be setup usually. In three-tier b/s structure mode, the client tier is browser, it must not be setup. The middle tier are web server and web application, the web server is only setup once, the application must not be setup usually, and it has good expansibility and convenient recomposition and short development cycle, so three-tier b/s structure become the main structure in the domain gradually. But in parent, the method on three-tier b/s structure has many defects. Now people need a kind of method, which is convenient, powerful, more security, high stability, good expansibility. This article produces a new method like that. The core on the new method is Web Service because it has many advantages. The new method base on the result of system analysis and system design. Every module is develop as a system service, and every system service is not only an application based on three-tier b/s structure but also a module of other system. Furthermore, these modules can be constitute to different information system at discretion. Among these modules, every module service has a exclusive ID, which is composed of IP and port number. Services can be use.d arbitrarily and they communicate by XML document and .share data through database. In order to check and examine this method, I use this method to develop a general bidding management information system. This MIS include six modules (security management, invite public bidding management, bidding management, evaluate bidding management, contract management, other management). Through the experiment, many advantages are found, such as convenience, powerful function, good security, high stability, good expansibility, can be used in different network, short develop cycle, economize cost and so on. This method can resolve the problem of system integration in the process of enterprise informatization and can help enterprise achieve enterprise informatization.