upport event driven communication
  between the application and the actors of the MVC triad.</p></p>
<p><p> An Observer is an object that encapsulates information
  about an interested object with a notification method that
  should be called when an <code>INotification</code> is broadcast. The Observer then
  acts as a proxy for notifying the interested object.</p>
<p><p>Observers can receive <code>Notification</code>s by having their
  <code>notifyObserver</code> method invoked, passing
  in an object imp