Research Of Three-Tiered Architecture On Hospital Information System

Hospital Information System (HIS for short) is the application in the hospital information management of the computer techniques, the communications techniques and the management science. And it is the chronic effect and saturation of the computer techniques to the hospital management, the clinic physic, the hospital information management and the outcome of the combination of each other.To a application system, the system famework mode is what should be taken into account. It haves the decisive effects on the cost, the performance, the agility, the security, the maintenance, and other aspects of the application system. Along with the hugeness and complication of the system, the traditional host/terminals or two-tiered client/server mode can not satisfy the users. Therefore the new distributed application system (three-tiered system) came into being. This question for discussion is the attempt and study of the developing of three-tiered HIS.Firstly, the paper introduces the definition, developing sense, development tendency of HIS, the aim and sense of this question for discussion.Because of the complexity and the special requirement, it is very difficult to develop the distributed application system. All software dealers agree to make use of three-tiered architecture to develop application system. The second chapter introduces the development requirement of the enterprise information system, the development course of the application system architecture, the variety system architecture mode application in HIS, and the virtues and shortcomings of two-tiered c/s and three-tiered c/s.The core tier (the middle tier) is business tier. It encapsulated business logical rules. The third chapter introduces the relational conceptions and the inner framework of the middle application of thre&tiered c/s, and two design mode of the business entity object relation: the centralized mode and the relation mode.In the example, Sql Server2000 is the DBMS and PowerBuilderT.O is the developing tool. The middle tier use ODBC to connect with DBMS and theclients use WinSock to communicate with the server. The realization of PB Distributed application is to initialize CCUO of server remotely on dent and to transfer the properties and methods of the object. The forth chapter introduces the architecture and the relation conceptions of the three-tiered distributed system, and the developing method, and the debugging of three-tiered application program.The fifth chapter introduces the development of three-tiered HIS, taking hospital diagnoses system as example. Including system analysis, database design, the developing of the server application and the client application, and the interfaces of all function module.Appendix I displays some of the program codes.