STUDY ON NATIVE XML DATABASE BASED GML STORAGE MODEL

摘要

As a mature spatial interoperability specification of OGC, GML rapidly plays an important role in a large number of GIS research and application domains, such as spatial data modelling, transmission and exchanging, integration and sharing, because of its advantages of opening and self-description format system, rich spatial data expression technology, flexible application schema and so on. However, the complexity of GML specification leads to bulkiness of GML data files, which limits extent of GML data sharing. Furthermore, its non-structural data model goes against its storage by commercial relational database, which ultimately result in low performance of GML application and destroy abundant semantic of GML data. Thus, appropriate GML storage approach would improve extend and depth of GML application.By analogy approach, this paper study on storage and manage model of XML data, analyze current status of GML storage method. Combining XML database with characteristic of GML spatial data, create GML storage mapping mechanism based on feature and storage granularity, form GML to Native XML Database Storage Model (G2NXDBM) consisted of GML file segment, GML schema file and GML storage log file. On the basics of JAXP (Java API for XML Processing) program API and open source code JTS (Java Topology Suite), the author developed G2NXDBMs prototype system which include schema mapping constructor and file storage tools depending on Ipedo native database by IPedo Inc.USA. To test the efficiency of GML query, the author selects 5 groups of test data with the same size. The experiment result demonstrates that although the storage space of G2NXDBMs is larger than GML file, it has more advantages of query efficiency, support of XML technology and data management than GML file and relational database storage, it also testify the validity and practicability of G2NXDBM.