The implement of virtual database based on mediator

Recently the research about virtual database is booming in grid technology and information integration which is rapidly responded. Major database vendors have introduced systems that help design and build federated database. These systems enable the professional developer to assemble the data source. Though these systems do use metadata catalogs and graphical navigation and selection tools, the developer is expected to have an intimate knowledge of the underlying structure of the source databases and files. Creating a query in virtual database, given the need to understand the corporate data sources and their structure, is a challenging task. The proposed system required the designer to only have a cursory knowledge of the structure of the data sources. This is accomplished by allowing more information in the metadata. The proposed system use middleware technology to eliminate structural differences and implement of the cross-platform virtual database.