SESSION VARIABLE BECOMES NULL AFTER SOME REFRESH

[MUKUND Premchander]

Hi,

I have a jsp page which is refreshed atuomatically every 10 seconds.I
get and put values in the session by using the implicit session variable
. Everything works fine for say 2-3 mins after that the session becomes
null and throws a null pointer exception. 

IN the try block I even have a code as 
try {
     if (session == null || session.isNew()) {
            //do something 
      } else {
             //do otherwise 
      }
 }catch(Exception e )
 { //print stack trace and value of session } 

I get a null pointer exception and session is preinted as null but even
the if block is noit executed . I printed the value of
request.getSession(false);.This gives me session object ,where as the
implicit session does not have this after many refresh interval . During
the first few refresh both have the same value. 

Also note that this runs fine in Windows ,I get this problem only in
UNIX . I use tomcat 3.2 in unix and view using IE in windows 

Please help me out as to where I am going wrong .
 
thanks and Regards
Mukund