Implementation of Remote Interface

Now you must create a server implementation of the remote interface (HelloInterface).

Responsibilities of a remote object implementation class:

• The class must implement at least one remote interface. It is possible for a single class to implement more than one remote interface.
• Define the constructor(s) for the remote object and declare its constructor(s) to throw RemoteException.
• Provide implementation for the methods that may be invoked by the client remotely.
• Export the object by extending the UnicastRemoteObjec class or use the exportObject() method of the same class.

In this example, the server class (HelloServerImpl) will implement the remote interface (HelloInterface) and extend UnicastRemoteObject (See Figure 3.1).

Figure 3.1

Listing 3.2 HelloServerImpl.java (Complete server code)

import java.rmi.*;
import java.rmi.server.*;
import java.net.MalformedURLException;

//server class
public class HelloServerImpl 
	extends UnicastRemoteObject 
	implements HelloInterface{
 
 //constructor
  public HelloServerImpl()
	throws RemoteException {
					
 	System.out.println("Creating server Object");
  }

		
 //remote method called by clients
 public String getMessage()
	throws RemoteException {
			
       return "Hello World";
  }
	
  //main method	
  public static void main(String []helloWorld) {

      try {

	  //create a server object
	  HelloServerImpl helloServer = new HelloServerImpl();
			
	  //bind the server
	  Naming.rebind("Server",helloServer);
	  System.out.println("Server Ready");
	 }catch(RemoteException ex) {
	     System.out.println("Error " +ex.getMessage());
	 }
	 catch(MalformedURLException ex) {
	     System.out.println("Error " +ex.getMessage());
	 }
    } 
}