摘要
Internet/Intranet的快速发展、数据仓库技术的应用 ,使得GIS空间数据管理与应用呈现多用户、分布式和网络化的特点。面对这一发展趋势 ,传统GIS软件平台普遍采取的单机或二级客户机 /服务器模式存在难以克服的缺陷 ,开发基于三级客户机 /服务器模式的GIS软件平台成为当前研究的重要课题。本文详细介绍了基于三级客户机 /服务器模式GIS软件平台的基本设计思路和体系结构 ,并且在此基础上 ,运用socket技术构造中间件 ,建立了一个试验性平台———VirtualWorld,同时介绍了在此体系上解决GIS互操作方案 ,最后对试验进行了简单分析。
The central or two_tiered Client/Server pattern have been adopted more commonly by most of traditional GIS platform.But now,accelerated by the development of Internet/Intranet,the spatial data management and application of GIS is tending to multi_user and network distribution.The spatial data can be efficiently Stored by the improved relational DBMS such as Oracle,DB2.It is possible for us to develope the large and distributed GIS application,but the inefficiency and worse security of traditional patterns restrict this developement.Compared to those patterns,the three_tiered Client/Server pattern has more advantage ,and fits the trendcy of spatial data management.It can solve the problem of effiency and security well.Above all it fits the demand of sptatial data warehouse,which will be built with the data warehouse technique and used to store and manange multiscale and spatial_temporal data in the future. In this paper,the design of this new kind of GIS platform,which is based on the the three_tiered Client/Server pattern,is introduced.This GIS platform consists of three components:the Client,the Server and the middleware.The Client has three components:the spatial data management module,the integrated GIS application and the ActiveX control .The spatial data management module is the base of client software,and includes the local issue of spatial data and communication with the middleware.The integrated GIS application,which is developed on the spatial management module directly,is GIS professional software like Editor.The ActiveX control is used to build a professional system by the developer.The middleware is a service to process the spatial data such as spatial analysis,data compression/decompression.It also provides the Client valid spatial data,which can reduce the burden of the network,and pass some command and new data from the client to the Server.The Server may be a improved relational DBMS which can store the spatial data efficiently ,or a service to read and edit the spatial data file ,which is stored with special format such as DXF format,Arc/Info shape file etc. The paper also shows a sample of this kind of platform,VirtualWorld software,and a application built with the VirtualWorld ActiveX control - the terrain explorer.In the application,the DEM data and the digital photogrammetric image are stored in the Oracle 8.1.6,which is installed on the Server.The three parts communicate the information with the socket. Finally ,a conclusion is made that the GIS platform based on the three_tiered pattern can optimize the structure of network,reduce the burden of the Server and Client,improve the efficiency of GIS system.Also ,some problems are pointed out.
出处
《武汉大学学报（信息科学版）》
EI
CSCD
北大核心
2001年第2期165-169,共5页
Geomatics and Information Science of Wuhan University
基金
国家杰出青年科学基金资助项目 ( 4 95 2 5 10 1)
