Research on three-layer B/s information system based on Java EE

With the increase of the scale and complexity of software system, the choice of software architecture becomes more important than the choice of data structure and algorithm, the three-tier client/server architecture provides a good framework for the integration of enterprise resource planning, and is the best choice for establishing enterprise management Information System. With the development of architecture and the development of software framework, there are different solutions for the implementation of Java technology and. NET technology in Multi-layer application structure, which are applicable to the requirements of different scale system respectively. This paper will combine the implementation of the Telecom Plan Construction Management Information System, explain the architecture of the three-tier model, introduce the Distributed component technology of the application system based on the three-layer model, and expound the implementation method of the application system by using the Java-EE frame structure.

I. The choice of system structure

1. Disadvantages of traditional two-layer C/s structure

The traditional two-tier client/server model is more suitable for small scale, less users, a single database and in a secure, fast network environment (such as LAN) running. However, the application model of the two-tier structure will not adapt as the application system expands and the complexity becomes more and more complex in a multi-user, multiple database and insecure network environment (e.g., the Internet). And the traditional two-tier structure also has the following defects:

(1) It is a single server and LAN-centric, so it is difficult to extend to large enterprises WAN or Intranet;

(2) Limited by the supplier, the upgrade and maintenance of the program must be expanded by the supplier redevelopment;

(3) Soft, hardware combination and integration capabilities are limited; The software presents a FAT client, the user must install a specific client application on the client, and the business logic of the Enterprise is written in the client application, the program is difficult to maintain, and the program upgrades require each client to install a new client application, For program developers, the reusability of program module is poor, each module is relatively independent;

(4) C/S mode is difficult to manage a large number of clients.

Based on the above reasons, the traditional C/S model has been unable to meet the needs of development, with the popularization of network technology and the further improvement of user needs, the three-tier web model emerged.

2, three-tier Web architecture benefits

The three-tier client/server model (three-tier model) adds a new level based on the two-tier model. This mode logically divides the application function into three layers: the customer display layer, the business logic layer, and the data layer. The customer display layer is a graphical interface to provide application services to customers, which helps users understand and efficiently locate application services. The business logic layer, located between the display layer and the data layer, provides a clear hierarchy of business logic for the enterprise, encapsulating the application model associated with the system at this level and separating the user presentation layer from the database code. This level provides a link between the client application and the data service, with the primary function of implementing the application policy and encapsulating the application pattern and rendering the encapsulated schema to the client application. The data tier is the lowest level in three-tier mode, which is used to define, maintain, access, and update data and to manage and satisfy requests for data from the application service.

The main advantages of the three-tier model are:

① good flexibility and scalability. For the environment and application conditions often change, as long as the application layer to implement the corresponding changes, can achieve the purpose.

② can be shared. A single application server can provide services to client applications on different platforms, saving development time and capital investment to a large extent;

③ is better security. In this architecture, client applications cannot directly access data, and application servers can control not only which data are changed and accessed, but also how data is changed and accessed.

④ enhances the duplication of availability of enterprise objects. Enterprise objects are objects that encapsulate the enterprise Logic program code to perform specific functions. With the development of component technology, this reusable component pattern is becoming more and more accepted by software development.

The ⑤ three layer model has become a real "thin client", which has a high stability, ductility and execution rate.

The ⑥ three-tier model can centralize service management and unify service to clients, thus possessing good fault tolerance and load balancing capability.

Three-tier architecture

The Telecommunication Plan Construction Management Information System is the unified management by the Province Telecommunication Company to the subordinate city Telecommunication Company, all business logic is concentrated in the provincial company management and Development, the city company is responsible for data entry and query statistics, the user's extensive distribution, data centralized processing, so in the design of the full consideration of the advantages and disadvantages of various architectures, Select three-tier Web mode for development implementation.