session persistance from server perspective

[yogesh srinivasan]

Hi Ranchers,

I wrote a simple code to understand sessions.
This code creates a session and adds a cookie and an attribute to a new session.
I restarted the tomcat and refreshed the stale browser. The session and its attribute were retained by the browser.
I thought the session and its attributes were created in server's memory and would be destroyed after the restart.
How this is possible?

   
import javax.servlet.*;
import java.io.*;
import javax.servlet.http.*;
public class test extends HttpServlet {
	int cookieCount=0;
	public void doPost(HttpServletRequest req, HttpServletResponse res)throws IOException, ServletException{
		HttpSession session= req.getSession();
		PrintWriter write = res.getWriter();
		Cookie[] cookies = req.getCookies();
		write.println("Session.isNew="+session.isNew());
		if(session.isNew()) {
			Cookie c = new Cookie("cookie1",Integer.toString(cookieCount++));
			res.addCookie(c);
		}
		if(cookies != null){
			for(Cookie temp : cookies){
				write.println("<br>cookie name= "+temp.getName()+" value= "+temp.getValue()+" maxAge= "+temp.getMaxAge());
			}
		}
		write.println("<br>session ID"+session.getId());
		write.println("<br>session MaxInactivInterval "+session.getMaxInactiveInterval());
	}

}
 

[Devaka Cooray]

yogesh srinivasan wrote:This code creates a session and adds a cookie and an attribute to a new session.

yogesh srinivasan wrote:The session and its attribute were retained by the browser.

Well,... I can't see a session attribute in your code. Can you?

Devaka.

[yogesh srinivasan]

oops..sorry forgot to add the latest code

import javax.servlet.*;
import java.io.*;
import javax.servlet.http.*;
public class test extends HttpServlet {
	int cookieCount=0;
	public void doPost(HttpServletRequest req, HttpServletResponse res)throws IOException, ServletException{
		HttpSession session= req.getSession();
		PrintWriter write = res.getWriter();
		Cookie[] cookies = req.getCookies();
		write.println("Session.isNew="+session.isNew());
		
		if(session.isNew()) {
			Cookie c = new Cookie("cookie1",Integer.toString(cookieCount));
			res.addCookie(c);
			session.setAttribute("attribute1",cookieCount);
			cookieCount++;
		}
		if(cookies != null){
			for(Cookie temp : cookies){
				write.println("<br>cookie name= "+temp.getName()+" value= "+temp.getValue()+" maxAge= "+temp.getMaxAge());
			}
		}
		write.println("<br>session ID"+session.getId());
		write.println("<br>session MaxInactivInterval "+session.getMaxInactiveInterval());
		write.println("<br>session attirbute1 value= "+(Integer)session.getAttribute("attribute1"));
	}

}    

[Sourin K. Sen]

tell us the outputs that you are getting prior to restarting the server and after restarting it.

[yogesh srinivasan]

step1 : create a sample home.html with a form triggereing the test servlet
step2 : output
Session.isNew=true
session ID42D3279AE5EF2FE634F0ECE96CAA583A
session MaxInactivInterval 1800
session attirbute1 value= 3
step3 : hit the back button and resubmit home.html
step 4 : output
Session.isNew=false
cookie name= cookie1 value= 3 maxAge= -1
cookie name= JSESSIONID value= 42D3279AE5EF2FE634F0ECE96CAA583A maxAge= -1
session ID42D3279AE5EF2FE634F0ECE96CAA583A
session MaxInactivInterval 1800
session attirbute1 value= 3
step 5 : shutdown and restart tomcat
step 6 : hit back button and resbmit
step 8 : output
Session.isNew=false
cookie name= cookie1 value= 3 maxAge= -1
cookie name= JSESSIONID value= 42D3279AE5EF2FE634F0ECE96CAA583A maxAge= -1
session ID42D3279AE5EF2FE634F0ECE96CAA583A
session MaxInactivInterval 1800
session attirbute1 value= 3

[I created 3 request to increment the cookieCount value]