title: Refresh a Servlet by another Servlet
body: <p>I have to create a little webshop for a school-project, but entered in to a problem during the process by updating/refreshing the <code>Servlets</code>.</p>
  
  <p>Description:
  I created an <code>index.html</code> file which includes two servlets via <code>iframes</code>, the left side for <code>Navigation-Servlet</code> and on the right the <code>Controller-Servlet</code> does something to show a welcome page (or shows off the categories etc.) - works all fine.</p>
  
  <p>But now I have to implement a login with an small administration.
  By clicking in the navigation on <code>Administration</code>, it leads to another <code>Servlet</code> called <code>Administration-Servlet</code>, in the right iframe (actually not over the <code>Controller-Servlet</code>).</p>
  
  <p>There comes up a login mask, where the user put in his username and password. If the login was correct, it leads then to the administration content (not finished by now).</p>
  
  <p>The upcoming problem is now that I somehow have to update/refresh the <code>Navigation iframe</code> too, when the login was successful because there must be the <code>Logout-Button</code> and some entries have to be hidden.</p>
  
  <p>By which "technique" or pattern I can solve this problem? Maybe a little code example would be helpful. :)</p>
  
  <p>Best greets.</p>