This book is split into three sections: Foundations, XML Vocabularies and Deployment.
The first section is an overview of the processes involved in modelling your XML applications with UML. I found this section to be largely irrelevant, and for a section entitled 'Foundations', I found it overly complex and hard to get through. The author used UML diagrams and a description of these diagrams to represent the tasks involved in designing an XML vocabulary.
The second section brightened me up a bit. Although at times, I still felt a bit lost when it came to the XML example used, the chapters in this section successfully achieved two things; Firstly they gave me a thorough introduction to the concepts being presented e.g. mapping UML class diagrams to XML; linking XML elements and defining DTDs and Schemas;and also to a whole range of XML technologies such as XPath, XPointer, and RSS. Secondly, they really got into the nitty-gritty of each of these topics. This is where the complex example came in handy - it gave the author the opportunity to demonstrate each of the concepts in meaningful terms.
The final section on deployment covers the real-world business scenarios in which your newly learned skills will be deployed. The book concludes with a brilliant introduction to the business case for XML Web Services.
Overall I would recommend this book as an accompaniment to the host of web-based materials that there are on the topic.