The Research Of Several Core Technology On Spatial Data Source Integration System Based On XQuery

Nowadays with the development of computer technology, especially the network technology, the geographic information system applies to many fields. The demand of spatial data increase rapidly.However, the spatial data source usually stores in different position and has different format. Therefore, to eliminate the difference of spatial data in storage format and position, let more and more users get the geography information faster and exacter, implement the real-time the function of data share, exchange and operation become the hot spot of research.The Mediator-Wrapper architecture was considered as the best solution for heterogeneous data source integration in recent years, by which we don't need to change the storage format of original data. This architecture corresponds the heterogeneous data source for lower layer and provides the uniform data model and access interface for upper layer. The Mediator-Wrapper architecture provides the foundation for implementing the mutual operation between the data source.Open GIS consortium constitute the superset of XML—GML(Geography Markup Language), which follow the organization feature of geography data. The appearance of GML is the foundation for solving the problem. As one of XML form for spatial code, GML should be took as the common data model in spatial data integration system, which can not only implement the spatial data sharing between different data source, but also implement the seamless link between the spatial data and non-spatial data to support integrated query by XQuery.Based on the above correlation research, this paper addresses a design proposal, which make XQuery support to the spatial data inquiry and spatial operation, by means of extending the XQuery language. Through rebuilding the representation of the XQuery data model, the seamless connection between GML spatial data and XML non-spatial data has been implemented and transformation of data format is reduced too so that efficiency is improved. In the spatial data integration based on GML and XQuery, spatial operation can be performed on spatial data from distribute data sources. Besides, we should optimize the management of data source adapter's module, which can get the data source adapters and load into system real-time, according to the user's query requirement, serving for the upper layer. It can better adapt the change requirement, reduce the degree of coupling, and improve the expansibility of the system.