RMI Client And RMI Server Implementation

The RMI application comprises of the two separate programs, a server and a client.

Introduction
The RMI application comprises of the two separate programs, a server and a client. A typical server program creates some remote objects, makes references to these objects accessible, and waits for clients to invoke methods on these objects. The RMI application provides the mechanism by which the server and the client communicate and pass information back and forth. The RMI distributed application uses the RMI Registry to obtain a reference to a remote object. The server calls the registry to associate a name with a remote object. The client looks up the remote object by its name in the server?s registry and then invokes a method on it.

Program description:
In this section, you will learn how to send massage from RmiClient to the RmiServer. Here, we are going to create "ReceiveMessageInterface" interface. The interface defines the methods that can be invoked from the client. Essentially, the interface defines the client's view of the remote object. After that, we will create a class named "RMIServer". The RMI Server accepts tasks from clients, runs the tasks, and returns any result. The server code consists of an interface and a class.

In this class, the ?receiveMessage()? method, which is called from the remote client, is defined. This class is the implementation of the RMI interface. The RmiServer creates the ?registry?. This is a kind of directory. Its key is a name (which is the ID of a remote object) and its content is an object. This object is looked up from a remote program by the name. This registry is accessed from a remote object by the IP address or host name and the port number.

createRegistry(): This is the method creates and exports a registry on the local host that accepts requests on the specified port.

ReceiveMessageInterface.java


import java.rmi.*;



public interface ReceiveMessageInterface extends Remote{

  void receiveMessage(String x) throws RemoteException;

}

The above code defines the RMI interface. The receiveMessage() method is implemented in the server class.

Here is the code of RMI Server:

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

public class RmiServer extends
java.rmi.server.UnicastRemoteObject implements ReceiveMessageInterface{
  String address;
  Registry registry;

  public void receiveMessage(String x) throws RemoteException{
  System.out.println(x);
  }

  public RmiServer() throws RemoteException{
  try{
  address = (InetAddress.getLocalHost()).toString();
  }
  catch(Exception e){
  System.out.println("can't get inet address.");
  }
  int port=3232;
  System.out.println("this address=" + address +  ",port=" + port);
  try{
  registry = LocateRegistry.createRegistry(port);
  registry.rebind("rmiServer", this);
  }
  catch(RemoteException e){
  System.out.println("remote exception"+ e);
  }
  }
  static public void main(String args[]){
  try{
  RmiServer server = new RmiServer();
  }
  catch (Exception e){
  e.printStackTrace();
  System.exit(1);
  }
  }
}

The above class uses LocateRegistry class to create a remote object registry that accepts calls on a specific port.

Download of this code.

Output of the above program:

C:\rose>javac RmiServer.java
C:\rose>java RmiServer
this address=roseindi/192.168.10.104,port=3232t=
_3232

Here is the code of RMI Client:


import java.rmi.*;

import java.rmi.registry.*;

import java.net.*;



public class RmiClient{

  static public void main(String args[]){

  ReceiveMessageInterface rmiServer;

  Registry registry;

  String serverAddress=args[0];

  String serverPort=args[1];

  String text=args[2];

  System.out.println

   ("sending " + text + " to " +serverAddress + ":" + serverPort);

  try{

  registry=LocateRegistry.getRegistry

 
(serverAddress,(new Integer(serverPort)).intValue());

  rmiServer=(ReceiveMessageInterface)(registry.lookup("rmiServer"));

  // call the remote method

  rmiServer.receiveMessage(text);

  }

  catch(RemoteException e){

  e.printStackTrace();

  }

  catch(NotBoundException e){

  System.err.println(e);

  }

  }

}

lookup(): This is the method that returns a reference, a stub, for the remote object associated with the specified name.

Output of the above program:

C:\rose>java RmiClient 192.168.10.104 3232 roseindia
sending roseindia to 192.168.10.104:3232

C:\rose>

If the RMI client sends any type of massage then massage will be displayed on the RMI Server.

C:\rose>java RmiServer
this address=roseindi/192.168.10.104,port=3232
roseindia

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RMI Client And RMI Server Implementation

RMI Client And RMI Server Implementation

RMI Client And RMI Server Implementation

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