Stateless vs Stateful Session Beans

[Riaan Nel]

Hi Guys

I wanted to try and illustrate the difference between the two types of beans for myself, so I created a couple of classes and remote interfaces as follows:

@Remote
public interface StatefulDemoRemote {
    public void call();
}

@Stateful
public class StatefulDemoBean implements StatefulDemoRemote {
    
    private int callCount = 0;
    
    public StatefulDemoBean() {
        
    }
    
    @Override
    public void call() {
        System.out.println("Stateful bean: " + ++callCount);
    }
}

@Remote
public interface StatelessDemoRemote {
    public void call();
}

@Stateless
public class StatelessDemoBean implements StatelessDemoRemote {
    
    private int callCount = 0;
    
    public StatelessDemoBean() {
        
    }
    
    @Override
    public void call() {
        System.out.println("Stateless bean: " + ++callCount);
    }
}

I then exposed the call() methods through a web service and invoked each of them four times. My output (in the Glassfish log) was as follows:

INFO: Stateless bean: 1
INFO: Stateful bean: 1
INFO: Stateless bean: 2
INFO: Stateful bean: 2
INFO: Stateless bean: 3
INFO: Stateful bean: 3
INFO: Stateless bean: 4
INFO: Stateful bean: 4

I was expecting the stateful bean's counter to be incremented with each call, but I didn't expect the stateless bean to do the same - I thought that it would essentially lose track of whatever state it was in (i.e. that it would be lost after being invoked, and that the next call would get a new instance). What am I missing?

Cheers,
Riaan

[Riaan Nel]

Anyone?

[Ragavan Natarajan]

This might help you.

http://www.coderanch.com/t/312022/EJB-JEE/java/Stateless-Session-Bean-maintain-state

[Riaan Nel]

Ragavan Natarajan wrote:This might help you.

http://www.coderanch.com/t/312022/EJB-JEE/java/Stateless-Session-Bean-maintain-state

Thank you Ragavan, and welcome to JavaRanch!