Logout

hi I am Abhijit. I coded this small module which uses session. But i want the logout functionality. Thus i used invalidate() function . This is my code

package com.abhi;

import javax.servlet.http.*;
import java.io.*;
import java.util.*;

public class WelcomeServlet extends HttpServlet 
{
	public void doGet(HttpServletRequest request,HttpServletResponse response)
	{
		HttpSession session = request.getSession();
		try 
		{
			PrintWriter writer = response.getWriter();
			if (session == null || session.isNew()) 
			{
				writer.println("You are not logged in");
			}
			else 
			{
				response.setContentType("text/html");
				writer.println("<html><body style=\"font-family:verdana;font-size:10pt\">");
				writer.println("<h1>Login Application using Session Tracking</h1>");
				writer.println("<p>Thank you, you are already logged in");
				writer.println("<p>Here is the data in your session");
				
				Enumeration names = session.getAttributeNames();
				while (names.hasMoreElements()) 
				{
					String name = (String) names.nextElement();
					Object value = session.getAttribute(name);
					writer.println("<p>name=" + name + " value=" + value);
				}
			}
			
			session.invalidate();
			writer.println("<p><a href=\"index.html\">Logout" + "</a> and return to login page");
			writer.println("</body></html>");
			writer.close();
		} 
		catch (Exception e) 
		{
			e.printStackTrace();
		}
	}
}

The rest is working good, it is printing the name - value pair in the while loop
My main concern is how to write a code which is based on login-logout function . If somebody help me it is very good for me.
When I click logout link it is going to login page, but when i again click the back button of the browser, it is again going back to the previous page instead of redirecting to the same login page
so please help me

In order to logout you must make a POST request to a special servlet, mapped at ibm_security_logout. You may check 'form logout example' section here to figure out how to setup you page to use form based logout facility.

thanks man ! but i use apache tomcat server not the Websphere so i don't know about ibm .

Well, then may be you shall post your question on Tomcat Forum instead of here.