Stateless Session Bean

[murali kankanala]

Hi Friends,

I have implemented a Stateless Session Bean, part of the code snippet is below.

public class CalculatorStatelessSessionBean implements SessionBean 
{
	private SessionContext ctx;
	//private UserTransaction userTran = null;
	//These two variables are to test whether stateless session is a able to remember previous state ( previous values).
	private double arg1;
	private double arg2;

        -----------
        -------------

        public double add(double arg1, double arg2) throws RemoteException 
	{
		//We are assigning to test whether stateless session is a able to remember previous state ( previous values).
		System.out.println("Previous arg1 = "+this.arg1);
		System.out.println("Previous arg2 = "+this.arg2);
		this.arg1 = arg1;
		this.arg2 = arg2;
		
		System.out.println("Current arg1 = "+arg1);
		System.out.println("Current arg2 = "+arg2);
		
		double result = arg1 + arg2;		
		return result;
	}
	 
}

ejb-jar .xml

<ejb-jar>
	<display-name>Calculator Service</display-name>
	<enterprise-beans>
		<session>
			<ejb-name>Calculator</ejb-name>
			<home>com.training.ejb.day1.statelesssessionbean.calculator.CalculatorHome</home>
			<remote>com.training.ejb.day1.statelesssessionbean.calculator.CalculatorRemote</remote>
			<ejb-class>com.training.ejb.day1.statelesssessionbean.calculator.CalculatorStatelessSessionBean</ejb-class>
			<session-type>Stateless</session-type>
			<transaction-type>Container</transaction-type>			
		</session>
	</enterprise-beans>
</ejb-jar>

Client code:

 //Get the remote interface by calling the home object's create() method
	          calculatorRemote = (CalculatorRemote) PortableRemoteObject.narrow(calculatorHome.create(), CalculatorRemote.class);
	          
	          System.out.println(calculatorRemote.add(10, 20));
	          System.out.println(calculatorRemote.subtract(10, 20));
	          System.out.println(calculatorRemote.multiply(10, 20));
	          System.out.println(calculatorRemote.devide(10, 20));

My problem is when i call add() method on stateless session bean i trying to store the values in the global variables, so when i call different method on the same bean, the previous values which i stored in the session as global variables able to retain. How this is happening.? According the Stateless session bean behaviour it should not remember the values which i stored as part of my first call to my first method right?

Can you please clarify me ?

Appreciate your help.


Thanks,
Murali

[Ninad Kulkarni]

Hi Murali,

You are using same calculatorRemote. Try using different instance of calculatorRemote and call appropriate method and post the result.

[murali kankanala]

Hi Ninad,

I agree with this, if i close the existing bean and create new bean obviously its brand new bean eventually its not going to remember what previous state.

Lets say i have another stateful session bean. Suppose if i create first bean and called add() method and closed the bean. I have created new bean and called add() method, here you mean to say that this 2nd bean can remember that state of the previous bean.add().

I am worried how to see the difference between Stateless and Stateful practically.

Could you help me earliest.


Thanks,
Murali

[murali kankanala]

I tried as you said,

	          //Get the remote interface by calling the home object's create() method
	          calculatorRemote1 = (CalculatorRemote) PortableRemoteObject.narrow(calculatorHome.create(), CalculatorRemote.class);
	          
	          System.out.println(calculatorRemote1.add(10, 20));   
	          calculatorRemote1.remove();

	          
	          //Get the remote interface by calling the home object's create() method
	          calculatorRemote2 = (CalculatorRemote) PortableRemoteObject.narrow(calculatorHome.create(), CalculatorRemote.class);
	          System.out.println(calculatorRemote2.add(10, 20));

I closed the first bean and created new one but the new bean is retaining the previous values of first bean.
Note: i am using same home refferencing.

[Ninad Kulkarni]

murali kankanala wrote:I am worried how to see the difference between Stateless and Stateful practically

In lifecycle of satefull session bean ejbActivate() & ejbPassivate() methods come into picture but not in lifecycle of stateless session bean