Quite often in a Struts application you have objects that need to be initialized only once when the application starts up. One good way to initialize these objects is to write a class that implements org.apache.struts.action.Plugin and put the initialization code in its init() method. You would then declare this plugin class in the struts-config.xml file with a <plug-in> tag. If you do this, the Struts ActionServlet will execute your logic when it initializes.
Many developers have found this a convenient way to initialize a Hibernate Session Factory, for example. [ September 06, 2006: Message edited by: Merrill Higginson ]