This Book

Most technical books are either tutorials or reference works. You turn to the former if you're looking for a gentle introduction to a new subject; you look to the latter if you already know something about the subject and want a minimum of hand-holding while you seek out the information you need. This book is unusual in that it shares some of the characteristics of each. It consists of a series of technical essays and perspectives, some of them tutorial-like, on various facets of XQuery from members of the World Wide Web Consortium's (W3C) Query working group , the standards body that has been hard at work creating and crafting the formal definition of the language since the fall of 1999. Their intimate knowledge sheds a lot of light on a technical topic that some find daunting, given the weight and density of the formal spec.

Members of the working group would probably be embarrassed to hear themselves referred to here as "experts," as the title implies, but that's what they are. Nobody knows the material better than this group ”after all, they created it! In this case you could say (pun intended) that they "wrote the book." And not just the one you're reading: They also wrote most of the specification itself, since nearly every one of the authors is also an editor of one or more of the numerous documents that comprise the formal specification.

In addition to being intimately involved in the creation of XQuery and the specification documents that define it (twelve at this point and counting), the credentials shared by the collective authorship of this book is impressive. They are researchers and theoreticians, software architects , product managers, educators, and database implementers. They are the designers of no less than six influential computer languages, including Haskell, Quilt, XML-QL, YATL, XQL, and SQL. Their views on query languages and XML are helping to shape the technology strategies of some of the most influential computer companies in the world. All in all, an impressive group! The "Contributors" section gives the bona fides of all our experts. It's worth perusing.

This book provides an opportunity for these people to write individually about the XQuery topics they know best and about which they are most passionate . It allows each of them to write with a personal voice and perspective in a way that's not possible within the carefully and consensually crafted framework of a formal standards specification.