EJB 3.0 Stateful bean not saving state while Stateless bean is !!!

Question

My Stateless bean is as follow:
package test;
import javax.ejb.Stateless;
@Stateless(mappedName = "StatelessBean")
public class StatelessBean implements StatelessBeanRemote {
     int counter;
     public void increment(){
          System.out.println("Stateless counter value:"+counter);
          counter++;
My Stateful bean is as follow:
package test;
import javax.ejb.Stateful;
@Stateful(mappedName = "StateFulBean")
public class StateFulBean implements StateFulBeanRemote {
     int counter;
     public void increment(){
          System.out.println("Stateful counter value:"+counter);
Client is as follows:
package test;
import java.util.Hashtable;
import javax.naming.Context;
import javax.naming.InitialContext;
public class TestClient {
     public static void main(String[] args) {
          Hashtable hashtable = new Hashtable();
          hashtable.put(Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory");
          hashtable.put(Context.PROVIDER_URL, "t3://localhost:7001");
          InitialContext ic;
          try {
               ic = new InitialContext(hashtable);
               StateFulBeanRemote stateFulBeanRemote = (StateFulBeanRemote)ic.lookup("StateFulBean#test.StateFulBeanRemote");
               stateFulBeanRemote.increment();
               StatelessBeanRemote statelessBeanRemote = (StatelessBeanRemote)ic.lookup("StatelessBean#test.StatelessBeanRemote");
               statelessBeanRemote.increment();
          } catch (Exception e) {
               e.printStackTrace();
The output i am getting after running the client twice is as follows:
//first time
Stateful counter value:0
Stateless counter value:0
//second time
Stateful counter value:0
Stateless counter value:1
Shouldn't the counter values be incremented in case of Stateful bean and remain the same for Stateless bean. But the output that I am getting is the complete opposite !!!
Can anyone please explain this confusing behavior of stateless and stateful ejb 3.0 beans.

Answer 1

868664 wrote:
Can anyone please explain this confusing behavior of stateless and stateful ejb 3.0 beans.It is very simple: a stateless bean is ASSUMED to be stateless; you cannot keep state in a stateless bean as a contractual rule. That doesn't mean that you will fail to keep state in them at least for a little while, they are still only Java objects. Generally stateless EJBs are pooled, so you may get the same instance each time you use such an EJB, but you may just get another one. It is not dependable and the rules say don't do it - so don't do it.
A stateful bean is tied to a single client, and so can be used by a client to keep state in it. Since You are running the client application twice you are operating with two different clients and so you will get a new stateful bean each time and your code will keep printing 0. However there is also a bug in your code:
public void increment(){
System.out.println("Stateful counter value:"+counter);
}You are not incrementing anything.