Simple class that holds the action mapping information used to invoke a Struts action. The name and namespace are required
ActionMapper:
When given an HttpServletRequest, the ActionMapper may return null if no action invocation request matches, or it may return an ActionMapping that describes an action invocation for the framework to try
ActionProxy:
ActionProxy is an extra layer between XWork and the action so that different proxies are possible.
ActionInvocation:
An ActionInvocation represents the execution state of an Action. It holds the Interceptors and the Action instance. By repeated re-entrant execution of the invoke() method, initially by the ActionProxy, then by the Interceptors, the Interceptors are all executed, and then the Action and the Result.