Linux Platform, The Research And Implementation Of Webgis Platform Based On The Vector Format,

As a combination of geography science and the information technology, the development of GIS has been closely related with the advancement of computer technology since its very beginning. In the 1990s, as the network technology developed quickly, WebGIS gradually took its shape and gained a booming development and gradually turned into an ideal form of geography information service.In the late 1990s, the diversification of the computer operating systems became more and more obvious especially at the server side. With the nature of open source and sound security, Linux has become a strong power both in server and PC market. The transition from Windows platform to Linux is not only a technical issue, given the factor of information security and the industry independence of a nation, it even bears much political meaning. Under such a trend, the research of WebGIS on Linux platform has naturally been a hot issue in GIS field.Supported by the Ministry of Construction, this paper just focuses on the research and implementation of a vertor format WebGIS system on the Linux platform.The paper firstly introduced several present methods to realize vector-formatted WebGIS and then made an analysis on the sever-side data organization, client interaction, application logic etc. Considering the characteristics of the software under Linux platform, the paper decides to use database to store and manage all the geographical data. Finally the open-sourse software of PostgreSQL was chosen due to its stability, extensibility and proper size. Also its exclusive GIS extention PostGIS was utilized as the base of application development.During the system design, the paper created the conception of Workspace,Layer and Skin to organize the data in database in accordance with the idea of Project and Layer in the mainstream GIS package. Extended functions for PostgreSQL are developed by PL/pgSQL in the form of embedded SQL functions to create, delete and manage the Workspace,Layer and Skin. Under the idea of moduliaztion, ahundant functions to interact with Workspace, Layer and Skin are coded in PHP language on the server side to handle all the map request. While on the client end, this implementation adopt Java Applet package and Javascript to achieve the map rendering, zooming, roaming, selecting and labeling and the interactive seaching on the server side.Finally the paper summarized the system design and the realization methods. Furthurly it presented the problems that need to be solved of this vector-formatted WebGIS in the future.