title: How to call Backing Bean method to fetch the request Header value from Incoming request and forward result to a JSF page
body: <p>My requirement is " Our users are Authenticated by External System using SSO". 
  On successful authentication the external system returns header variables viz. userId,
  firstName, lastName etc to our System. 
  Currently I am able to retrieve these header variables using
  request.getHeader("userId") in my JSP page.</p>
  
  <p>But I am using JSF 2.0 and not able to figure out as to how this can be done in JSF. I saw one example here on Stack overflow ...</p>
  
  <pre><code>Map&lt;String, String&gt; requestHeaders = context.getExternalContext().getRequestHeaderMap(); 
  String userName = requestHeaders.get(requestHeaderName); 
  </code></pre>
  
  <p>but there was no further response as how this will be invoked on the backing bean.</p>
  
  <p>Any pointer or sample code would be helpful.</p>