Research On Online Updating Of Geographic Feature Services

The emergence of Geographic Information Service can not only provide a better solution to the sharing and interoperability of multi-source heterogeneous spatial data,but also could promote the realizing of sharing and interoperability of the distributed cross-platform spatial processing capabilities.The face of the traditional method of geospatial data updating can't satisfy people's current potential of spatial data,and a new updated way to the online updating of geographic feature services thanks to the ideal of Geographic Information Service.The research was focused on the network transmission efficiency of GML data,transaction concurrency control,updating processing service implementation,and the prototype system of online updating of geographic feature services platform was constructed according to the problems faced in the process of online updating of geographic features.The main work of this paper is as follows:1.The application requirements of research on online updating of geographic features were analyzed mainly on spatial information sharing and interoperability,the applications of Geographic Information Service and the mode of geographic features updating.According to the related research status at home and abroad,the problems existing in the current study and the insufficiency were analyzed.The main contents and structure of this paper was proposed combined with the background and significance of this paper.2.The theory which could support Web Services basics of Geographic Information Service,OGC Web Service Framework and OGC Geographic Information Service specifications was researched.The implementation specification,working principle of Web Feature Service(WFS)and the relationship between GML data and WFS were analyzed.The basic content of GML encoding specification,including the core mode of GML and the relationship of expanding GML core model and GML data was studied.3.The converting method of common spatial data formats(SHP and TAB)and GML data were realized on the basis of vector data accessing OGR library.A GML data compression method adapted to network transmission was proposed on the basis of analysis of the data redundancy type and common GML data compression methods with describing the implementation process in detail,including GML data stream separation process,the method of data portion compression,structure portion compression and merge.4.The common methods of geographic features updating were analyzed from the content,mode and period of geographic features updating,and the method of online updating of geographic features based on WFS was proposed according to the characteristic that WFS have the ability to support the geographic features transaction operations.A multi-version concurrency control of WFS features updating management solution was designed to solve the concurrency conflicts of multi-user requesting or accessing WFS features at one time,taking example by database concurrency transaction control methods.The Web Processing Service(WPS)used for online updating of geographic features and WPS client was developed.5.The framework of online updating of geographic features services for online updating of geographic features was designed on the basis of SOA idea and OWS Framework.The prototype system platform of online updating of geographic feature services was built to verify the three Key technologies which were proposed in this thesis and an online updating of geographical features platform client was achieved based on Open Layers and GeoExt.In the end the adding and deletion operations in the process of geographic features updating were verified with the geographic features processing services which was published in this thesis.