Study On GML-based Spatial Database Storage And Retrieving Model

With the great improvement of digital life, the Geographical Information System(GIS) is widely used. However, differences among platform architectures and varieties of spatial data formats have severely restricted the further development of GIS. The XML (extensible Markup Language) brings a revolutionary mechanism to storage and transfer of information. Based on XML, Open GIS Consortium (OGC) has defined GML, the geographical markup language. Spatial data organized and represented with GML have features of standardization and structurization. Currently, it is also the only way to implement interoperation among GIS software with different architectures.This paper analyzes the spatial data storage modes used by most of GIS software. File storage mode is firstly stated including brief description of several kinds of popular file formats. GML is introduced to overcome obstacles of data sharing among them. Its data expression ability and current development situation are also discussed. Then database storage mode is discussed. We lay importance on the advantages and disadvantages of RDB, ORDB and OODB in storing spatial data.The aim of this paper is to explore a more effective data storage mode that combines high-efficient data management capability of RDB with the standard data format of GML. For this purpose, we propose the spatial data storage model, which can directly store GML data in the RDB and retrieve requested data to dynamically generate GML file for the clients.Based on this model, we have design and realize a prototype system to directly access the spatial data in RDB using GML. Its main functions, system structure and design, database design, and other key parts have been described in detail.We have solved most technical problems in the development of this prototype system. Its executing processes and test results are typical and constant, so the conclusion of this paper has a fair academic and practical value, and can be used to guide the research and development of related GIS software.