SQL level global query resolving for web based GIS

This paper introduced a SQL level approach to resolve global spatial query in Web based heterogeneous distributed spatial database environment. The main prohibit of this SQL level approach was its widespread compatibility and standardization. Firstly, a SQL based Equivalent Distributed Program (EDP) was introduced to express distributed spatial processing transactions. Then global resource directories for virtual global view describing were discussed to organize information that resolving need. The contents of global resource directories included data storage directory, hosts directory and working status directory. With these mechanisms, relational algebra expression equivalence principles were utilized to resolve global spatial queries to EDPs. Finally, several samples were presented to show the process of resolving. This approach was suitable to all sorts of distributed computing environments either centralized such as CORBA or decentralized such as P2P computing platforms.