Research On Spatiotemporal Data Modeling Approach Based On XML

Spatiotemporal database is a dababase management system, which aims at supporting spatiotemporal data management and has wide application requirements in traffic management, city zoning, forest fire monitoring and so on. Since continuous emergence of those complicated application, spatiotemporal data management problems become increasingly prominent. As a result, research on spatiotemporal data management has great significance. Spatiotemporal data model is the foundation of implementing spatiotemporal data management, which describes spatiotemporal objects in the real world and their relationship and provides basic method for spatiotemporal data management. Recently, XML has been the de-facto standard of data representation and exchange on the Internet. It has self-describing, flexible data structure, and power of data representation. Consequently, it has great significance in modeling spatiotemporal data based on XML.In previous studies, spatiotemporal snapshot model, base state and amendment model, spatiotemporal cube model, spatiotemporal composite model, and spatiotemporal object model etc. were presented. However, as these models adopt version to represent states of spatiotemporal object and query spatiotemporal changes by means of differences between versions, they cannot deal with spatiotemporal changes of more than one object. Accordingly, their query efficiency is low and they have weak support to spatiotemporal changes.In this paper, after introducing time semantics and spatial semantics, time characteristics and spatial characteristics are presented in detail. We make analysis in existing spatiotemporal data models and point out their shortages respectively. Modeling based on XML has great significance after we introduce characteristics of XML. After that, a spatiotemporal data model is put forward based on XML. It can describe changing history of spatiotemporal object according to the model; it can also describe attribute changes, containing thematic attribute changes and spatial attribute changes. Spatial attribute changes describe position and motion of spatiotemporal object. Spatiotemporal operations are classified according to spatiotemporal data characters and its completeness and mutually exclusion are proved. Next, definitions of each spatiotemporal operation are given. Since introducing spatiotemporal operation fuctions after each definition, they are explained by examples. Finally, I illustrate how to query spatiotemporal operations using XQuery according to the architecture of spatiotemporal data query processing, which testifies correctness and effectiveness of the proposed model.