Research of a QPC-based heterogeneous database query method

Regarding the problems of the combination of inquiries in several heterogeneous databases and inter-accessing among several heterogeneous databases, this paper proposes the Query Processing Center (QPC), which based on the virtual view method. With this method, all the users and databases could connect to the QPC via Internet and constitute a star topology. QPC provides service of query according to the user power permission, the source database management module can make databases conveniently add and delete just like plug-and -play devices. When a query is accepted by QPC, the QPC will check its correctness, decompose it into several subqueries and convert them into XML format, then the converted subqueries are send to the source databases. After get the search results, each result is converted into database format, then they are merged into one as the final result and sent to users finally.