Many Jakarta projects read XML configuration files to provide initialization
of various Java objects within the system. There are several ways of doing
this, and the Digester component was designed to provide a common
implementation that can be used in many different projects.

Basically, the Digester package lets you configure an XML ->
Java object mapping module, which triggers certain actions called
rules whenever a particular pattern of nested XML elements is
recognized. A rich set of predefined rules is available for your
use, or you can also create your own. Advanced features of Digester
include:

• Ability to plug in your own pattern matching engine, if the standard one
  is not sufficient for your requirements.


• Optional namespace-aware processing, so that you can define rules that
  are relevant only to a particular XML namespace.


• Encapsulation of Rules into RuleSets that can be
  easily and conveniently reused in more than one application that requires
  the same type of processing.