Modern database systems enhance the capabilities of traditional database systems by their ability to handle any kind of data, including text, image, audio, and video. Today, databasesystemsareparticularlyrelevanttotheWeb, astheycanprovideinputtocontent generators for Web pages, and can handle queries issued over the Internet. The eXtensible Markup Language (XML) is used in applications running the gamut from content management through publishing to Web services and e-commerce. It is used as the universal communication language for exchanging music and graphics as well as purchase orders and...