Research Of The Key Technologies Of Geographic Information Service Based On Grid

Geographic information service based on grid is an emerging part of geographic information science. It covers many theories and technologies. This paper firstly discusses some basic theories including grid, geographic information service grid and its structure, and then focuses on four crucial issues: spatial data model based on grid, network storage framework of geographic information based on grid, construction technology of geographic information service based on grid, and combination of geographic information service. During the research some new conceptions, models and methods are developed and the technologies are testified by experiments and applications. All the work that will help greatly further study on grid-based geographic information service includes:1. Make a detailed investigation on the geographic information service framework based on network. Describe and define the compositions of geographic information service, and determine layers of geographic information service, their functions and the relations. Provide a complete framework and a primary guide for geographic information service.2. Construct a spatial data model oriented to the share and inter-manipulation of geographic information. The four inconsistencies of spatial data are always difficulties in geographic information science and limit the widespread of geographic information service. Handle each inconsistency respectively and build a reasonable model of spatial data. This thesis achieve a unified interface to the grid environment heterogeneous spatial data access and integration.3. Propose and construct a network storage engine of spatial data based on grid. Realize storage of spatial data that is located in different places and effective management using grid, server cluster, spatial data division, and data distribution to the storage devices linked by high-speed network.4. Suggest and built an algorithm of spatial data index and a buffer memory structure of spatial data that both suits the geographic information service based on grid. Spatial index and cache are important solutions of the optimization of the geographic information service based on grid. Design and implement a multi-level cache and a two-layer and self-adapted spatial index model.5. Using Web service technique, implement a grid geographic information service based on WSRF standard. Furthermore, implement two basic geographic information services, web feature service and web map service.6. Introduce ontology to geographic information service to resolve the matching and meaning description in the combination of geographic information service. And realize meaning description of geographic information service and matching algorithm of geographic information based on meaning.7. Suggest a structure of the combination of geographic information service. Explore the thought, algorithm, and process of Web service combination and design an ontology-based combination method of web geographic information service that supports dynamical combination.