Aimed at readers already familiar with database concepts, the book includes little introductory material. It quickly lays out the concepts of self-describing semi-structured data and how XML fits into this approach to data representation. The discussion deals with XML as a data transfer mechanism and not a presentation language. While there is a quick explanation of DTDs, Xlink, and XPointer, readers should be fairly familiar with XML before approaching this advanced title.
The meat of the book revolves around query languages for XML. The authors present XML-QL and XSL in depth as examples. Then they move into much more advanced concepts such as schema formalisms, path constraints, and storage architectures. The book wraps up with a look at Lore and Strudel--two real-world systems that work with semi-structured data. Because of its intensive study of database and query theory, this textbook isn't for the ordinary Web developer. If data architectures are your expertise, however, Data on the Web may open new design doors. --Stephen W. Plain
Topics covered: Object database models, basic XML syntax, UnQL, XML-QL, XSL, StruQL, schema formalisms, extracting schemas from queries, semistructured data servers, Lore, Strudel, and XML-based database products.