Problem in understanding session beans

[Poornima Sharma]

Hi Friends,

I am a novice in ejb and I am finding it very hard to understand stateful and stateless session beans. As we all know stateful session beans are used when we want to maintain a state. Here as per my understanding is maintaining a session by the container. Such as what all activities are being done in a particular session.

To implement this I made a very small program of stateless and stateful session bean and connected this ejb module with struts via Guice DI framework.

The following is my stateful and stateless code:-

package ejb;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.ejb.Stateful;

@Stateful(mappedName="ejb/Stateful")
public class MySessionStateful implements MyStatefulInterface 
{

	private int i=0;
	
	@Override
	public void display() {
		System.out.println("displaying stateful session bean "+ i++);
		
	}
	
	@PostConstruct
	public void initialize()
	{
		System.out.println("Stateful session bean initialized");
	}
	
	@PreDestroy
	public void cleanUp()
	{
		System.out.println("Cleanup of stateful session bean");
	}

}

package ejb;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.ejb.Stateful;
import javax.ejb.Stateless;

@Stateless(mappedName="ejb/MySessionInterface")
public class MySessionStateless implements MyStatelessInterface 
{

	private int i=0;
	@Override
	public void display() {
		System.out.println("displaying stateless session bean for "+ i++ + "times");
		
	}
	
	@PostConstruct
	public void initialize()
	{
		System.out.println("Post construct of stateless session bean");
	}
	
	@PreDestroy
	public void cleanup()
	{
		System.out.println("Cleanup of stateless sessionbean");
	}

}

Here both the interfaces are remote.


My problem is:- Whenever I call a struts action method method which internally calls the stateless session bean from one particular browser the bean is initialized (only once for one browser) and the value of i is incremented by 1. This increment happens each time i call the bean method. If i call stateless session bean from another browser a new stateless session bean is created, and its postconstruct method is executed and the value of i is initialized.

However when i call a method that calls the stateful session bean, each time i call the stateful session bean from the same browser, it is initialized and a new value of i is used. It has become so confusing for me.

Please guide.