The article compares several universal integration techniques and methods via to access and integrate Spatial Heterogeneous Data on GIS. And in the paper

the authors discuss the key theory and technique of Spatial Heterogeneous Data Integration. Last

we give emphasis introducing the Integration method based on XML and Middleware technique. And we consider that the most major of XML is the independence of it's data storage format with display form. Along with the development of RDF and VDB

with data describing tool and transition tool based on XML by way of integration layer

middleware possessing capability of data sources integration is suit to the need of spatial heterogeneous data source integration.