XQuery from the Experts: A Guide to the W3C XML Query Language

Rating:
Summary: Nice coverage of XQuery/XPath
Review: A very useful explanation of XQuery and how to use it to analyse XML data. The book shows how this can be done with or without a supporting XML Schema or DTD that describes the XML. The authors explain why this goes beyond a Google-type search. The latter does not (at least currently) know or use any structural information about data, primarily because it scans all types of mostly unstructured data.

But the rise of XML has driven demand for XQuery, to take advantage of this structure. The book also shows how XPath is used, as part of the XQuery implementation.

Another merit of the book is its good description of the difference between XQuery and XSLT. The latter also has been getting a lot of attention from programmers. But, as explained by the authors, XSLT is mainly used on document centric data, mostly to generate HTML. By contrast, XQuery has no such restriction.

Rating:
Summary: Excellent survey of a complex topic by some of the designers
Review: Full disclosure: I know all of the authors and count them among my friends.

In spite of that, I can honestly say that I think this book is a very valuable guide to the emerging standard query language for XML. The insights provided by people who are actually doing the day-to-day design, and implementation in some cases, of this language are not available in any other XQuery book.

The various chapters of the book provide overviews, design precepts, detailed examples, and thorough explanations (even of subjects as arcane as the static typing rules of the language).

I enthusiastically encourage everybody interested in XQuery to add this book to their libraries.

Rating:
Summary: Very informative set of essays
Review: Simply good. A collection of essays written by so many well-known names in the industry covering various aspects of the XQuery language from a "A Guided Tour" to "Introduction to Formal Semantics". A book that would be very useful for people with XSLT background, and need more power to do their job. A book that closes the between Relational Databases and XML.

A good number of authors and innovators contributed materials to this book:
- Don Chamberlin (an editor of the XML Query Use Cases, XQuery 1.0, XML Path Language 2.0 working drafts),
- Denise Draper (one of the editors of XQuery 1.0 Formal Semantics),
- Mary Fernandez (one of the editors of the working drafts of XQuery 1.0, XPath 2.0 Data Model, XML Path Language and XQuery 1.0 Formal Semantics),
- Howard Katz (editor of this book)
- Michael Kay (an editor of the XSLT, XSLT 2.0 and XQuery Serialization and XML Path Language 2.0 working drafts)
- Jonathan Robie (an editor of XQuery 1.0, XML Query Requirements, XML Syntax for XQuery 1.0 and XPath 2.0 working drafts)
- Michael Rys (an editor of the XQuery Formal Semantics, XML Syntax for XQuery, XML Query Requirements, XML Query and the XPath Full-Text Requirements working drafts)
- Jerome Simeon (an editor of XQuery 1.0, XPath 2.0 and the XQuery Formal Semantics working drafts)
- Jim Tivy (System architect of the ODMC 1.0 SQL Engine for Microsoft)
- Philip Walder (an editor of the XQuery, XPath Formal Semantics and the XML Schema working drafts)

Even though that some of the chapter in this book will benefit an expert programmer, with a solid background in XML, there are more than enough chapter that will benefit the beginner and one's who are no really familiar with XPath, XQuery and XSLT. The book starts by going over the basics of the XQuery language. The Guided Tour is simply a refresher, and introduces the reader to XQuery and its syntax/semantics. It talks about the differences between XPath and XQuery for example, and the benefits of XQuery over XPath. Small code sections are used to convey to the read the difference of one technology versus the other. XPath and XQuery get a lot of attention in this book as there are lots of similarities between the two as far as syntax is concerned and plenty of difference as far as its capabilities with XPath.
The author[s] dedicate the second chapter to the principles behind the design decisions of the XQuery language. Don Chamberlin, the author of this chapter, write the following mission statement for XQuery:
"The purpose of the new query language was to provide a flexability to extract information from real and virtual XML documents."
It is very refreshing to see the committee for creating XML actually went to the process of defining requirements, design definitions and the rest of the formal specification realization before they actually "wrote" the language. The message of formalism is very clear throughout the book. At each stage of design for this new language, proper documents have been generated (Use Case doc, Requirements doc, etc) that portray a good process. The section on formal semantics adds the following:
"After the Java programming language was released, several formal semantics of the language were written. Some of these semantics revealed errors in the type system, which in turn could lead to security holes in browsers that run Java programs. ..."

XQuery looks very similar to XPath, and this book spends a couple of chapters (a little of chapter 2, and most of chapter 3) to talk about the similarities, differences and influences of one language over the other. The new releases of XSTL, XPath and XQuery 1.0 look very similar since these groups collaborated with each other throughout the process of development. If you don't know anything about XPath or XSLT, and want to know how they differ and hoe they have evolved in the recent years, chapter 3, by Michael Kay, is what you need to read - or may even start with before you read the other chapters in this book. Chapter 3 starts off very easy, but it goes into more advanced topics such as optimization techniques used with XQuery - specially the one's that have been used before with XSLT and XPath for the same purpose.
One of the most interesting chapters in this book is chapter 5 on Formal Semantics. It is rare and rather refreshing to see a language being broken up like that and it's predicate logic and semantics be given in such detail. You can skip this chapter all together, but I suggest otherwise. Even if it is to realize how language processing and semantics of a language work. I would love to see such topic for C++ or JAVA... This chapter is good for anyone interested in optimization techniques and wishes to learn more about the details and correctness of the XQuery language.
Applications of XQuery at they apply to Databases and how it can be integrated into databases are covered in part 4.
XQuery had the capability to navigate, select, combine, transform, sort and aggregate XML data - thus making the integration of XQuery with the backend database very powerful and rather simple. XML data, and how it can be integrated into the database with the help of XQuery is covered in detail and two techniques are laid out: the LOB (large object) representation where the entire XML data is saved as a large object in the database, and the composed representation where each XML element is stored individually.
Even though XQuery is fairly a new language, the authors in this book go to great length depicting the formalism, the correctness, the stability and flexibility of the XQuery language. The chapters that cover Database integration with XML data clearly convey the power of this language, and thought process that went behind designing such stable and powerful language.

Rating:
Summary: Very informative set of essays
Review: Simply good. A collection of essays written by so many well-known names in the industry covering various aspects of the XQuery language from a "A Guided Tour" to "Introduction to Formal Semantics". A book that would be very useful for people with XSLT background, and need more power to do their job. A book that closes the between Relational Databases and XML.

A good number of authors and innovators contributed materials to this book:
-Don Chamberlin (an editor of the XML Query Use Cases, XQuery 1.0, XML Path Language 2.0 working drafts),
-Denise Draper (one of the editors of XQuery 1.0 Formal Semantics),
-Mary Fernandez (one of the editors of the working drafts of XQuery 1.0, XPath 2.0 Data Model, XML Path Language and XQuery 1.0 Formal Semantics),
-Howard Katz (editor of this book)
-Michael Kay (an editor of the XSLT, XSLT 2.0 and XQuery Serialization and XML Path Language 2.0 working drafts)
-Jonathan Robie (an editor of XQuery 1.0, XML Query Requirements, XML Syntax for XQuery 1.0 and XPath 2.0 working drafts)
-Michael Rys (an editor of the XQuery Formal Semantics, XML Syntax for XQuery, XML Query Requirements, XML Query and the XPath Full-Text Requirements working drafts)
-Jerome Simeon (an editor of XQuery 1.0, XPath 2.0 and the XQuery Formal Semantics working drafts)
-Jim Tivy (System architect of the ODMC 1.0 SQL Engine for Microsoft)
-Philip Walder (an editor of the XQuery, XPath Formal Semantics and the XML Schema working drafts)

Even though that some of the chapter in this book will benefit an expert programmer, with a solid background in XML, there are more than enough chapter that will benefit the beginner and one's who are no really familiar with XPath, XQuery and XSLT. The book starts by going over the basics of the XQuery language. The Guided Tour is simply a refresher, and introduces the reader to XQuery and its syntax/semantics. It talks about the differences between XPath and XQuery for example, and the benefits of XQuery over XPath. Small code sections are used to convey to the read the difference of one technology versus the other. XPath and XQuery get a lot of attention in this book as there are lots of similarities between the two as far as syntax is concerned and plenty of difference as far as its capabilities with XPath.
The author[s] dedicate the second chapter to the principles behind the design decisions of the XQuery language. Don Chamberlin, the author of this chapter, write the following mission statement for XQuery:
"The purpose of the new query language was to provide a flexability to extract information from real and virtual XML documents."
It is very refreshing to see the committee for creating XML actually went to the process of defining requirements, design definitions and the rest of the formal specification realization before they actually "wrote" the language. The message of formalism is very clear throughout the book. At each stage of design for this new language, proper documents have been generated (Use Case doc, Requirements doc, etc) that portray a good process. The section on formal semantics adds the following:
"After the Java programming language was released, several formal semantics of the language were written. Some of these semantics revealed errors in the type system, which in turn could lead to security holes in browsers that run Java programs. ..."

XQuery looks very similar to XPath, and this book spends a couple of chapters (a little of chapter 2, and most of chapter 3) to talk about the similarities, differences and influences of one language over the other. The new releases of XSTL, XPath and XQuery 1.0 look very similar since these groups collaborated with each other throughout the process of development. If you don't know anything about XPath or XSLT, and want to know how they differ and hoe they have evolved in the recent years, chapter 3, by Michael Kay, is what you need to read - or may even start with before you read the other chapters in this book. Chapter 3 starts off very easy, but it goes into more advanced topics such as optimization techniques used with XQuery - specially the one's that have been used before with XSLT and XPath for the same purpose.
One of the most interesting chapters in this book is chapter 5 on Formal Semantics. It is rare and rather refreshing to see a language being broken up like that and it's predicate logic and semantics be given in such detail. You can skip this chapter all together, but I suggest otherwise. Even if it is to realize how language processing and semantics of a language work. I would love to see such topic for C++ or JAVA... This chapter is good for anyone interested in optimization techniques and wishes to learn more about the details and correctness of the XQuery language.
Applications of XQuery at they apply to Databases and how it can be integrated into databases are covered in part 4.
XQuery had the capability to navigate, select, combine, transform, sort and aggregate XML data - thus making the integration of XQuery with the backend database very powerful and rather simple. XML data, and how it can be integrated into the database with the help of XQuery is covered in detail and two techniques are laid out: the LOB (large object) representation where the entire XML data is saved as a large object in the database, and the composed representation where each XML element is stored individually.
Even though XQuery is fairly a new language, the authors in this book go to great length depicting the formalism, the correctness, the stability and flexibility of the XQuery language. The chapters that cover Database integration with XML data clearly convey the power of this language, and thought process that went behind designing such stable and powerful language.

Rating:
Summary: An excellent XQuery starter book and reference
Review: This book is a compact and thorough guide to XQuery. The Jonathan Robie tutorial in the beginning of the book is itself worth the overall price of the book.

Rating:
Summary: A masterpiece you can not afford to miss
Review: This book is written to be accessible to novices and still very effective for experts.
It explains the rationale behind the XQuery language and describes how XML, XQuery, and relational databases work together.

Jonathan Robie does an excellent job in the introductory chapter with exquisite style using compact examples.
Michael Kay and his insuperable acknowledge outlines differences and commonalities between XSLT and XQuery.

I did not find one chapter I wish it wasn't there.

Suggested audience may vary from XML enthusiastic to data integration architects.

Ivan Pedruzzi
Stylus Studio Team

Rating:
Summary: Is the right book for you?
Review: This book serves three groups of readers well: those who simply want to know about XQuery, those who are implementing XQuery functionality within their applications and those who are wondering how XQuery will impact what they already know how to do.

For the first group of potential readers, I doubt you'll find a book that better explains what ideas were essential in the design of the language, how it evolved to where it is at today and why it does what it does. There isn't a chapter in this book that isn't applicable to what you'll want to know and every essential landmark is set out for you. Don't expect this book to be a tutorial on how to use XQuery - we're likely too far away from a consistent standard for that. Do, however, expect to learn what XQuery is, why it's the way it is and where it fits in your bag of tricks. People in this group will especially like chapters two and three.

The second group of potential readers are probably either thinking about adding XQuery functionality to some sort of Database Management System or design or develop applications what use such systems. For you, I think this book is an excellent primer to read before reading the XQuery specification and before you start to get your hands dirty. Chapters four through seven will give you lots of things to ponder and insight into making good decisions early.

Personally, I mostly belong in the last group of potential readers - those who are wondering what XQuery means to them in the day-to-day, hand-to-hand combat of designing and developing end user applications. Is this a book you'll probably want? I think so. The first chapter does a good job of covering just enough of the language to get you going, and chapters three, and six, seven and eight will help you understand when, where and how XQuery needs to become part of your toolkit. I think this is especially true for those of us who make heavy use of Microsoft's .NET technologies and SQL Server products. As you likely already know, the next generation of these products are very much embracing XML within the database. Chapters six and seven offer an especially good view of where we're at today and where we're likely to be within the next year-and-a-half or so. I'd especially recommend this book for you.

Some things worth noting: chapter three is especially helpful for understanding the similarities and differences between XQuery, XPath and XSLT. To really understand where XQuery fits, you must understand this interrelationship Not only does Mr. Kay do a great job explaining that, he actually makes it fun to read. Similarly, if you are eager to discover what SQL Server "Yukon" might be like, then chapter seven contributed by Microsoft's own Michael Rys definitely seems to frame a map for you. On the downside however, this book does suffer from trying to be too many things to too many people. Although well written and interesting, chapters four and five essentially provide a Rosetta Stone to reading the XQuery specifications. If you're just looking for the basics of XQuery, you can likely safely save these reading chapters for some other time and place. Finally, if you're looking for a book that simply covers how to write XQueries, you can stop after chapter one. Chances are you will want to supplement this title with another book written to a more pedagogical theme.

Summary: a fantastic book for some, a good book for many.

Rating:
Summary: Good for XQuery side topics
Review: This is a good book if you know what you are getting. If you are looking for a focused guide to XQuery practical applications you aren't going to like this book. It's worth repeating, this is not a general reference or introduction to XQuery. This is a set of articles on XQuery related topics. The first 'chapter' is an introduction to XQuery which is actually quite good. After that is a chapter on the history of XQuery. Then there is a chapter on XSLT and XPath, which is a nice, but brief, introduction to those topics. There is a section on the semantics of XQuery which is so thick you could cut it with a knife. The book finishes with two chapters on relational to XML mapping.

If you are a serious XQuery user, are interested in a case study in standards development, or are into relational theory this book is probably worth a look.

Rating:
Summary: Good, for a limited audience
Review: This is a good quality book - for a certain audience. It is of interest to people who are writing XQuery processors, and people who have an academic interest in XQuery. It is definitely not for the average person who will be writing queries - only the first chapter would be useful to them. It goes into great depth about the formal semantics, the type system, etc - the kind of stuff 90% of the people using XQuery will never bother to learn. If you're interested in that kind of "theoretical" information, buy this book. If you're looking for a tutorial or a reference for how to write XQuery queries, look elsewhere.