| By making a thorough analysis on the history, current situation, research field, supporting technologies and existed problems, the dissertation clarifies the functions and implementation of architecture of Web GIS. Having analyzed the relevant phenomena of technology, the author brings out some new viewpoints and technical ideas about Web GIS. The technical problems of software are analyzed from the view of the framework in building Web GIS. In this dissertation, we investigate on the theoretical and technical problems of integration, share and interoperation of web-based geographic information service by combining with the origination and development of Web service theory and technology and aiming at the requirement of orientation, share, conformity and service of geographic information resource. On the basis of systematic study and discussion on network optimization in geographic information system and taking the requirements of specific fields into consideration, we put forward the techniques of network analysis for specific field and the tactics of Web GIS network optimization.The major contributions and innovations of this research include:1) Starting from the history and supporting technologies of GIS, the origin, process of development and current situation of Web GIS are deeply discussed, and its intension and research direction are meticulously analyzed. The theories, technical contents, key research points and development trend of Web GIS are also systematically described. Moreover, the development principles of Web GIS are expounded and a preliminary theoretical architecture of Web GIS is subsequently established.2 ) In light with the features of Web GIS information transmission, the author put forward an information transmission model for Web GIS, which comprehensively express the concentration, distribution and movement of data and computation in Web GIS. In fact, it is a new method to analyze the architecture of Web GIS. On this basis, the architecture of Web GIS is deeply discussed in detail. The techniques of classification and implementation for Web GIS are also investigated based on the architecture of Web GIS.3) Web-based geographic information service is a coupling of web service and geographic information system, which changes GIS into various data and function services in internet. Having studied and analyzed on the conceptual model of geographic information Web service, the author puts forward the viewpoint that it is necessary to build a platform of geographic information service in order to implement the geographic information Web service. On this basis, the structural model, framework, operation, technique, system structure and application integration of the platform are deeply discussed and investigated.4) The availability and practicality of service are determined by QoS and both aspects have influence on the popularity of service. The author puts forward the concept of QoS in geographic information web service and discusses the acquirement of user service, the service capability of service provider and service management in this connection.5) In order to overcome the limitations of the traditional arc-node data model, the author puts forward an object-oriented data model that is suitable for geographic network expression and operation, designs the conceptual and logic modeling methodologies of geographic network model, and on this basis, deeply investigates the construction of logic network based on geometric network and the topologic expression in logic network.6) The tactics for the implementation of network optimization in Web GIS are studied and a system of network analysis and application for specific fields is initially established combining with the development and construction of the Geographic Information system of Kunmings Public Security and the Service System of Urban Logistics Distribution.
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