How to Call RMI Service using Servlet Application

on February 3, 2017

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Call RMI Service using Servlet Application

In this example, I will show you how to call RMI service using servlet application. This example was tested with Apache Tomcat environment and output has been shared in the same post.

1. Developing RMI Service

In this part, we are going to develop the RMI Service, Which can be called by the servlet application.

Project Structure

How to Call RMI Service using Servlet Application

Creating the Interface

package com.dineshkrish.rmi;
import java.rmi.Remote;
import java.rmi.RemoteException;
/**
* 
* @author Dinesh Krishnan
*
*/
public interface Authentication extends Remote {
public boolean authenticate(String userName, String password) throws RemoteException;
}

Implementing the Interface

package com.dineshkrish.rmi;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
/**
* 
* @author Dinesh Krishnan
*
*/
public class AuthenticationImpl extends UnicastRemoteObject implements Authentication {
protected AuthenticationImpl() throws RemoteException {
}
@Override
public boolean authenticate(String userName, String password)
throws RemoteException {
if ((userName != null && !userName.isEmpty())
&& (password != null && !password.isEmpty())) {
if ((userName.equalsIgnoreCase("admin"))
&& (password.equalsIgnoreCase("admin"))) {
return true;
}
}
return false;
}
}

Publishing the Service

package com.dineshkrish.rmi;
import java.rmi.AlreadyBoundException;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
/**
* 
* @author Dinesh Krishnan
*
*/
public class Publish {
// Port Number you can change based on your system availability
private static final int PORT = 5252;
public static void main(String[] args) {
try {
// Defining Object
Authentication authentication = new AuthenticationImpl();
// Creating RMI Registry with Port
Registry registry = LocateRegistry.createRegistry(PORT);
// Binding the Object
registry.bind("auth", authentication);
System.out.println("Authentication Service running at " + PORT
+ " port...");
} catch (RemoteException e) {
System.out.println(e.getMessage());
e.printStackTrace();
} catch (AlreadyBoundException e) {
System.out.println(e.getMessage());
e.printStackTrace();
}
}
}

Run it

Authentication Service running at 5252 port…

2. Developing the Servlet Application

Project Structure

How to Call RMI Service using Servlet Application

Servlet Class

package com.dineshkrish.controller;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.dineshkrish.model.AuthenticationService;
/**
* 
* @author Dinesh Krishnan
*
*/
public class LoginController extends HttpServlet {
private String userName;
private String password;
@Override
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
userName = request.getParameter("userName");
password = request.getParameter("password");
if ((userName != null && !userName.isEmpty()) && password != null
&& !password.isEmpty()) {
AuthenticationService service = new AuthenticationService();
boolean status = service.verifyUser(userName, password);
if(status) {
RequestDispatcher dispatcher = request.getRequestDispatcher("success.html");
dispatcher.forward(request, response);
} else {
RequestDispatcher dispatcher = request.getRequestDispatcher("error.html");
dispatcher.forward(request, response);
}
} else {
RequestDispatcher dispatcher = request.getRequestDispatcher("error.html");
dispatcher.forward(request, response);
}
}
}

Calling the RMI Service

package com.dineshkrish.model;
import java.net.MalformedURLException;
import java.rmi.Naming;
import java.rmi.NotBoundException;
import java.rmi.RemoteException;
import com.dineshkrish.rmi.Authentication;
/**
* 
* @author Dinesh Krishnan
*
*/
public class AuthenticationService {
private final String SERVICE_URL = "rmi://localhost:5252/auth";
public boolean verifyUser(String userName, String password) {
try {
Authentication authentication = (Authentication)Naming.lookup(SERVICE_URL);
return authentication.authenticate(userName, password);
} catch (MalformedURLException | RemoteException | NotBoundException e) {
System.out.println(e.getMessage());
e.printStackTrace();
}
return false;
}
}

Developing Views Component

login.html

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Login Application</title>
</head>
<body>
<form action="login" method="post">
<h1>Login Page!!!</h1>
<table cellpadding="5" cellspacing="5">
<tr>
<td><label>Username</label></td>
<td><input type="text" name="userName" /></td>
</tr>
<tr>
<td><label>Password</label></td>
<td><input type="password" name="password" /></td>
</tr>
<tr>
<td></td>
<td align="right"><input type="submit" value="Login" /></td>
</tr>
</table>
</form>
</body>
</html>

success.html

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Success Page | Login Servlet + RMI Example</title>
</head>
<body>
<h1>You are logged in successfully...</h1>
</body>
</html>

error.html

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Error Page | Login Servlet + RMI Example</title>
</head>
<body>
<h1>Your Username / Password is incorrect...</h1>
</body>
</html>

Configuration File web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
id="WebApp_ID" version="3.0">
<display-name>LoginClient</display-name>
<welcome-file-list>
<welcome-file>login.html</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>Login</servlet-name>
<servlet-class>com.dineshkrish.controller.LoginController</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
</web-app>