What is the EJB Client?

Question

ALL, I am a newbie for EJB of Java World, After reading the good book named Ejb3.0 in Action, I have a question about Session Bean. What is the EJB Client for a session bean? Say we have some code looks like below.

//EJB definition
import javax.ejb.Remote;
@Remote
public interface PlaceOrder {
  ..
  void addItem(Long itemId);
  Long confirmOrder(); 
  ..
}

@Stateful
public class PlaceOrderBean implements PlaceOrder {
  private List<Long> items;
  public PlaceOrderBean () {
    items = new ArrayList<Long>();
  }

  public void addItem(Long itemId) {
    items.add(itemId);
  }

  @Remove
  public Long confirmOrder() {
    Order order = new Order();
    ...
    return order.getOrderId();
  }
}


//Client 
import javax.ejb.EJB;
public class PlaceOrderTestClient {
  @EJB
  private static PlaceOrder placeOrder1;
  @EJB
  private static PlaceOrder placeOrder2;
  public static void main(String [] args) throws Exception {
    System.out.println("Exercising PlaceOrder EJB...");
    placeOrder1.addItem(new Long(200));
    placeOrder1.addItem(new Long(201));

    Long orderId = placeOrder1.confirmOrder();
    System.out.println("Order confirmation number: " + orderId);
  }
}

Updated

The EJB Client means placeOrder1 and placeOrder2 or the main application ? Does it means multiple EJB clients? Another question is what if it is in Servlet instead of main method ? thanks.

Answer 1

EJBClient is a local program which can call and operate Remote Bean

Here, in your scenario whatever triggers the PlaceOrderBean is a client

InCase of Servlet, if Servlet calls the EJB it is technically client but often called Facade