how to use local & remote intefaces in ejb3

[sanjay nitwal]

hi
i am not able to understand the concept of local & remote


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

package com.ericsson;
import javax.ejb.Local;

@Local
public interface calcSumLocal {
	String sumOFnum(int i,int j);

}

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

package com.ericsson;

import javax.ejb.EJB;
import javax.ejb.Stateless;

/**
 * Session Bean implementation class calcSum
 */
@Stateless
public class calcSum implements calcSumLocal {

    /**
     * Default constructor. 
     */
    public calcSum() {
        // TODO Auto-generated constructor stub
    	
    }
    @Override
    public String sumOFnum(int i, int j) {
    	// TODO Auto-generated method stub
    	return (""+(i+j));
    }

}

----------client---------

package com.ericsson;

//import calcSumLocal;

import javax.ejb.EJB;


public class testApp {

	@EJB 
	public static  calcSumLocal c1;
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		System.out.println(c1.sumOFnum(2,3));
		
	}

}

this bean is deploying properly but when i am running the client it is giving exception


Exception in thread "main" java.lang.NullPointerException
at com.ericsson.testApp.main(testApp.java:18)

[Nick Potter]

You must also deploy the client, or use JNDI to remotely invoke the bean.

[Jeanne Boyarsky]

Sanjay,
Welcome to JavaRanch! I've added [ code ] tags to make your post easier to read.

There are a few ways of calling an EJB:

from a servlet and auto-injecting

from another EJB and auto-injecting

from an application client - don't remember if injecting works here

looking up the JNDI name

[sanjay nitwal]

Nick Potter wrote:You must also deploy the client, or use JNDI to remotely invoke the bean.

hi
i know remotly accessing ejb
my question is how can i access it localy ? because it is giving nullpointer exception

[Jonh Smith]

As already pointed out,

A) if you're calling the ejb from a stand-alone client outside the jee container, then there are two things wrong with your approach:

- the ejb needs to be remote
- you cannot use resource injection ("@EJB"). you have to use jndi lookup instead.

B) If on the other hand you're using your jee server application client container to run the client you may use injection but the ejb still needs to be remote (check this link : http://docs.sun.com/app/docs/doc/820-4336/beakv?a=view)


To access an ejb locally, the client app needs to be part of the same deployed application, whether it is a servlet, an ejb or simply a pojo.
Even inside the container, injection only works inside ejbs(3.0) and servlets (since 2.5, if I'm not mistaken), not POJOs. For the later, you do have to use jndi lookup.
You may use the "java:comp/env/<BeanName>" jndi name if you're in case B and do define a reference to the ejb in your app-client dd. This is necessary for the container to create a reference to the ejb in that jndi tree.
If you're in case A, you have to use the global jndi name to lookup your ejb, which you can get by checking your container's jndi browser.

[sanjay nitwal]

hi

I am calling the ejb from client inside the same jee container
My application is working fine using jndi lookup but problem is how to use the (@EJB) dependency injection.



:confused:

[Jonh Smith]

Besides what others and i have already told you, i can only suggest further that you confirm that you're using an ejb 3.0 container and not a 2.1 one. I do suggest you read the link i provided you and the jee tutorial about ejbs .

[Dejan Mratinkovic]

[quote]I am calling the ejb from client inside the same jee container[/quote]



Your sample code does not look like you do it. I looks like it is standalone program outside of jee container.