Listing 13.2 LazyServerImpl.java

import java.rmi.*;
import java.rmi.activation.*;

public class LazyServerImpl extends Activatable 
	implements LazyInterface {

  //this constructor is called by the
  //method ActivationInstantiator.newInstance during
  //activation process, to construct the object.
  public LazyServerImpl(ActivationID id, MarshalledObject data) 
	throws RemoteException {

    //Register the object with the activation system and
    //then export it. 
   super(id, 0);
 }
	
 //Remote method 
 public String sayHello() throws RemoteException {
	return "Hello World!";
  }
}

Explanation of Code

The implementation class declares which remote interface(s) it is implementing. Here is the LazyServerImpl class declaration:

public class LazyServerImpl extends Activatable 
	implements LazyInterface {

The Activatable class provides support for remote objects that require persistent access over time and that can be activated by the system on demand.

The constructor registers the object with the activation system.

public LazyServerImpl(ActivationID id, MarshalledObject data) 
	throws RemoteException {
   
    super(id, 0);
 }

Our next task is to provide implementation for each remote method. In this example, the remote interface contains only one remote method sayHello(). Here is the implementation for the sayHello() method, which returns the string "Hello World!" to the client:

public String sayHello() throws RemoteException {
	return "Hello World!";
  }