Based On A Grid Of Heterogeneous Spatial Data Distributed Query

At present, the processing of spatial data in the field of Spatial Information Science shows explosive growth. At the same time, with the development of the database technology, the unification of heterogeneous spatial database integration and query has become a important issue to be settled urgently. The development of grid technology with a unified access interfacing the existing spatial database to achieve the distributed heterogeneous resources on how spatial data retrieval and query, is a hot issue processing of spatial data.Query and retrieval is one of most frequent functions for using spatial data. The majority of question that the users ask in GIS could express for the query form. But for the particularity and the complexity of spatial data which cause difficulty for the inquiry. Therefore, to unify both the grid technology and the spatial data management technology with the grid technology together with its large-scale data processing and computation ability is the effective way to solute above mentioned problem.This paper based on the grid middleware technology method and thorough analysis of the spatial data put forward the method of Spatial Data Grid which unifies both of them, to solve the management question of the heterogeneous spatial data, and providing effective method and means for the space data processing in resources organization and applies.The Spatial Data Grid is the important constituent of Grid GIS, and is also the foundation of the Spatial Information Grid. At present the Spatial Data Grid research is still on the start stage, has not formed the unified construction and the system.Because the present OGSA architecture cannot support to the effective management of the spatial data yet, this paper mainly adopt two processing methods to realize the distributed query operation for the two heterogeneous spatial database of Microsoft SQL Server 2000 and Oracle10g:One of the two processing methods through the expansion of access and integration of the grid middleware OGSA-DAI activity,and adopts DAI offering a set of API for the client-side development, to combine with a set of the client-side JavaAPI offered by ArcSDE. The other adopts grid distributed query processing middleware OGSA-DQP offering user-defined methods, the DQPFactory class used in creating GDQS digital data service resources and the DQPQuery class used in carrying out the SQL query.The former processing method through introducing the spatial database engine into DAI data services,and the expansion of DAI activity to realize the spatial data positioning and integration in spatial databases, shielding heterogeneous of the system and database at the same time. The latter one through rewriting DQP user-defined methods for the two heterogeneous spatial database of Microsoft SQL Server 2000 and Oracle10g, and then it initially solved the management problem of heterogeneous spatial data.