Java Enterprise Best Practices

DOM

DOM, the Document Object Model, is a far better understood API than SAX. This is largely because it operates using more familiar Java principles: the XML input document is represented as a set of Java objects, output is performed via DOM serializers, and the ability to make significant programming errors is greatly lessened compared to SAX. However, DOM still presents more than its fair share of pitfalls to the unprepared developer.

When deciding to use DOM, you should always begin by first determining if you can use SAX. While SAX programming is generally more complex than DOM programming, it is almost always faster. However, if you were unable to answer “yes” to all the questions in the Section 5.2 , DOM might be a better solution for you.

In particular, there are two things that DOM excels at:

• Providing an object model of an XML document

• Providing access to all parts of an XML document at one time

These two aspects of DOM are interesting in that they both are significantly appealing to Java developers. On the whole, today’s developers prefer using an object-oriented programming model and having an entire business unit (whether it be an XML document or some other construct) available for random access at all times. SAX forces a more procedural and generally unfamiliar programming model, while DOM’s model seems more natural.

Of course, you pay performance and memory penalties for these features—keeping an entire document in memory and representing that document as objects expends ...