The Study And Application Of Component In Geographical Information System Based On COM

In software industry, the technology based on component is current hotspot,in the development of object-oriented technology today, as reuse software module, components solved the repetition developing problems and enhanced the efficiency which software developed in the software system development .Similarly, as one kind of domain software, the GIS system had evolved to the comGIS and webGIS in the development pattern gradually, therefore it is great significance to apply component technology to GIS system.The price of domestic and foreign molding commercial geography information system software is expensive and can hardly provide appropriation functions, so the developers must grasp two time development languages which the corporation provides to carry on the GIS system developments again. In addition, the system scale is bigger and is higher to the software and hardware.It went against to expansion, and also had no system independent copyright.But the component GIS system may better solve all the problems above, it divided GIS system into each big function module controls, which can complete different function. Each GIS controls, as well as GIS controls with non-GIS controls, may conveniently integrate through the visible software development kit, forming the GIS application software finally. Developers need not to be familiar with appropriation two time developments language, but needs to grasp GIS function and the general development language.Therefore it has the great significance to explore GIS system based on components.Based on the soft component technology and the COM model, the article designed and achieved GIS components which carried out partial function of GIS system, such as input and output of map the edition of map the bidirectional inquiry the spatial analysis and so on, in the research and development independently,the article unceasingly explores and consummates the development technology, develops the independent copyright software product. This article is directly based on COM level GIS system component technology, which reduced endurance to these special-purpose components, and can carry out the GIS component according to user's concrete demand, enhancing the flexibility of the system.In the studies of GIS system, in order to reduce the greatest limit repetition work, the article discussed the design pattern in the GIS system application and applied them in the system successfully. On determining the module system overall frame ,this article used Microsoft Visual C++ development environment, providedthrough ATL, achieving ActiveX controls. Through the method, attribute and event controls offer, it can alternate with client application well. The client application can better integrate with GIS system seamlessly.According to the GIS characteristic, the GIS module prototype system can apply in the actual GIS system. The map-shown component and the map edition component can integrate to the small GIS system, which are provided with basic GIS functions. It prepares the matting for the following expansion and the promotion.