Verify if a user can be authenticated.
An authenticator can implement all the usual component lifecycle interfaces
and gets the information set.
An authenticator must be implemented in a thread safe manner!
author: Carsten Ziegeler version: CVS $Id: Authenticator.java 433543 2006-08-22 06:22:54Z crossley $
Inner Class :public static class AuthenticationResult
Try to authenticate the user.
An AuthenticationResult that is either valid (authenticationsuccessful) or invalid (authentication failed. throws: ProcessingException - Only if an error occurs
This notifies the authenticator that a user logs out of the given
handler.
After the authenticator is notified, the AuthenticationManager
removes the authentication context, eventually the session etc.