Example: Tracking Number of Concurrent Users

• Implement the HttpSessionListener interface:
  • sessionCreated()
  • sessionDestroyed()
• A ConcurrentUserTracker class that implements HttpSessionListener.
• A DisplayUsers Servlet that uses ConcurrentUserTracker.
• http://redrock.d.umn.edu:8082/jspbook/DisplayUsers
  • Reload this page as different users access the site
• The rest of the Servlet event listeners behave similarly.