Virtual database technology: transforming the Internet into a database

Much of the world´s data lies outside relational databases-scattered across Web sites, file systems, nonrelational databases, and legacy applications. These data sources differ in the way they organize data, in the vocabulary they use, and in their data-access or query mechanisms. These differences make it difficult to combine data from multiple sources. Virtual database (VDB) technology makes external data sources act as an extension of an enterprise´s relational database system. Using VDB technology, applications can make powerful queries of data scattered over a variety of sources. The VDB gathers, structures, and integrates the data from these sources, and gives the application programmer the appearance of a single, unified RDBMS