Java and XML, 3rd Edition

Chapter 5. DOM

SAX is just one of several APIs that allow XML work to be done within Java. This chapter and the next will widen your API knowledge as I introduce the Document Object Model, commonly called the DOM. This API is quite a bit different from SAX, and complements the Simple API for XML in many ways. You’ll need both, as well as the other APIs and tools in the rest of this book, to be a competent XML developer.

Because DOM is fundamentally different from SAX, I’ll spend a good bit of time discussing the concepts behind DOM, and why it might be used instead of SAX for certain applications. Selecting any XML API involves tradeoffs, and choosing between DOM and SAX is certainly no exception. I’ll move on to possibly the most important topic: code. I’ll introduce you to a utility class that serializes DOM trees and will provide a pretty good look at the DOM structure and related classes. This will get you ready for some more advanced DOM work.

The Document Object Model

The DOM, unlike SAX, has its origins in the World Wide Web Consortium (W3C; online at http://www.w3.org). Whereas SAX is public domain software, developed through long discussions on the XML-dev mailing list, DOM is a standard—just like the actual XML specification. The DOM is designed to represent the content and model of XML documents across all programming languages and tools. On top of that specification, there are several language bindings. These bindings exist for JavaScript, Java, CORBA, and other languages, ...