Research And Design Of A System For Managing Geospatial Metadata Based On XML

With the rapid development of information technologies, metadata technology is becoming more and more important as one of the main technical supports of digital earth strategy. Geospatial metadata is the background information which describes the content, quality, representation, spatial reference, management and other appropriate characteristics of spatial datasets. It is helpful for users to understand, discovery, locate, mine, evaluate and maintain these spatial data. The target of this paper is to have a research on the content and organization of Geospatial metadata, to design and develop a management system for Geospatial metadata with the ability to collect store and search them.We first review the current situation of metadata technology, and point out the tendency of close combination of metadata technology with computer technology and G1S technology. Then we conclude the relevant concepts of geospatial metadata, and study its contents and hierachical structure by comparing two most influential metadata standards. Also we analyze three existing systems with emphasis on their architectures and implemental strategies. XML is a self-description and semi-structured language for web application. For the sake of its flourishing development and some advantages that it shows in the data representation, transfer, transmission and query, it will have a wide range of applications in the metadata field. So we briefly introduce such XML technologies as XML1.0. XML Schema, XSLT and XQuery.The metadata management must be performed according to its characteristics and the application's needs. This paper gives a total frame for the geospatial metadata's management system and function division of those modules toward their implementation.In view of the preliminary study and small scales application, the flat file system is adapted to build a spatial metadata database. We design the interfaces of a metadata engine. According to the characteristics of the user's request for metadata, we give a solution on how to create index on XML document collection and to search those metadata records. For metadata retrieval, a good system has to give support to the Z39.50 protocol. This paper introduce this information retrieval protocol in brief, then design the Z39.50 kernel, client-, server, gateway and search engine in detail.Finally, we implement a prototype of such system. Also we have a conclusion on our work, and propose the next to do.