Implementation Of Remote Method Invocation Concept In Java

Remote Method Invocation

RMI (Remote Method Invocation) is a way that a programmer, using the Java programming language and development environment, can write object-oriented programming in which objects on different computers can interact in a distributed network.

Working with RMI

1. Interface program
2. Implementation program
3. Server program
4. Client program

Example: Calculating the factorial of a given number using RMI concept.

Step 1: Interface Program

Declare the Methods only.

Open the first note pad, type the following program, and save the file as “rint.java”.

Interface Program (rint.java)

import java.rmi.*;
public interface rint extends Remote // rint is the interface name
{
    double fact(double x) throws RemoteException; // fact() is the method declaration only
}

Step 2: Implementation Program

Define the Methods only.

Open the second note pad, type the following program, and save the file as “rimp.java”.

 

Implementation Program (rimp.java)

import java.rmi.*;
import java.rmi.server.*;
public class rimp extends UnicastRemoteObject implements rint // rimp is implementation name
{
    public rimp() throws RemoteException // rimp() is constructor
        {}
    public double fact(double x) throws RemoteException // fact() method definition
        {
            if (x <= 1) return (1);
            else return (x * fact(x - 1));
        }
}

Step 3: Server Program

It is the main program.

Open the third note pad, type the following program, and save the file as “rser.java”.

 

Server Program (rser.java)

import java.rmi.*;
import java.net.*;
public class rser // rser is server name
{
    public static void main(String arg[]) {
        try {
            rimp ri = new rimp();
            Naming.rebind("rser", ri);
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

Step 4: Client Program

It is the data send (request) to the Server program.

Open the fourth note pad, type the following program, and save the file as “rcli.java”.

Client Program (rcli.java)

import java.rmi.*;
public class rcli // rcli is client name
{
    public static void main(String arg[]) {
        try {
            rint rr = (rint) Naming.lookup("rmi://172.16.13.2/rser"); // system IP address
            double s = rr.fact(5);
            System.out.println("Factorial value is… : " + s);
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

Explanation

Compile and Execute the Program.

In a single system, let us assume that we can open two command prompts. One command prompt is called Server while the other one is called Client.

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Step 2



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Summary: In the above blog, the remote method invocation concept has been implemented successfully.