The Approach of Land Administration Information System with Middleware Technology

The rapid advance of middleware technology is one of the most important characteristics in software development in recent year. This paper introduces the application of middleware technology, the software and design of the Nanhai land administration information system (NHLAIS).CORBA and DCOM provide complete and effective mechanism for the application, combination and management of software from different platforms. These series of technological break through bring out the combinization of software application and the componentization of software production. By combing the different software from different places effectively, the combinization resolves the application problem. The software system is decomposed into several independent components by the componentization technology of software production. Through standard system,,environment such as ActiveX and OpenDoc, these GIS components can realize the system combination effectively by connecting with other non-GIS components. The middleware refers to the software Shielding the difference between the operation system and netware protocol, providing the communication service among the system of different architectures. The Client/Server mode of three tiers based on middleware divide the application logic into three parts. Indication logic (Client tier)——the first tier, realizes the friendly interaction between the user and system,transfers the coral service the operation logic, displays the operation result. Operation Logic (Server component)——the middle tier, realizes the coral operation logic, manages and receives service request from the Clients, transfers data operation to resource manager, returns the operation result to the applicants——Client or other Server. The management of data of application system is executed in the data manager the third tier. In general the middleware has the following categories:remote procedure call(RPC), message-oriented middleware(MOM), object request brokers(ORB), database access(DA), and distributes transaction processing(DTP).NHLAIS is a wild area network (WAN) system. The center of the network is located in the Nanhai City Land Bureau. The 20 town sub-bureaus serve as the node of the network. Inside the City hand Bureaus a 100MB local area network (LAN) based on TCP/IP adapting Windows NT server and Windows 98. A proxy server communicates with the ISP through optical fibre. The application program in the workstations of the town sub-bureaus communicates with the ISP through the dialing mode. The non-spatial data is managed by SQL Server 6.5 from Microsoft.The SDE for SQL Server from ERSI manages the majority of the spatial data. With SDE the speed of loading map is enhanced. The cleaveless space database is established. The burden of the network is lowered. In NHLAIS, the Active Report of microsoft is adapted for the report output.MO from ESRI is adapted for the communication with different categories of map.