Java Remote Method Invocation (RMI) with Secure Socket Layer (SSL)

In this post I will demonstrate how a Java Remote Method Invocation (RMI) application can make remote invocations over Secure Socket Layer (SSL) connections.

Environment

Microsoft Windows 7
java version "1.7.0_09"
Java(TM) SE Runtime Environment (build 1.7.0_09-b05)
Java HotSpot(TM) 64-Bit Server VM (build 23.5-b02, mixed mode) 

Before we actually start coding the RMI Client and Server, we have to do following:

• Create a KeyStore and Generate a Public-Private Key
• Export a X.509 Certificate against above Key into a file
• Create a TrustStore and Import X.509 Certificate as a Trusted Certificate

Define RMI Remote Interface

	/**
	* Java Remote Method Invocation (RMI) with Secure Socket Layer (SSL)
	* http://codeoftheday.blogspot.com/2013/07/java-remote-method-invocation-rmi-with.html
	*/
	package smhumayun.codeoftheday.RmiOverSslTest;
	import java.rmi.Remote;
	import java.rmi.RemoteException;
	/**
	* Central Time Service is used by all clients to synchronize time with server
	*
	* User: smhumayun
	* Date: 7/4/13
	* Time: 8:20 AM
	*/
	public interface CentralTimeService extends Remote {
	/**
	* Port where this service is exposed via RMI over SSL
	*/
	int PORT = 8844;
	/**
	* Return current time in milliseconds on server
	*
	* @return current time on server in milliseconds
	* @throws RemoteException
	*/
	long getTime () throws RemoteException;
	}

view raw CentralTimeService.java hosted with ❤ by GitHub

Implement RMI Remote Interface

	/**
	* Java Remote Method Invocation (RMI) with Secure Socket Layer (SSL)
	* http://codeoftheday.blogspot.com/2013/07/java-remote-method-invocation-rmi-with.html
	*/
	package smhumayun.codeoftheday.RmiOverSslTest;
	import javax.rmi.ssl.SslRMIClientSocketFactory;
	import javax.rmi.ssl.SslRMIServerSocketFactory;
	import java.rmi.RemoteException;
	import java.rmi.registry.LocateRegistry;
	import java.rmi.registry.Registry;
	import java.rmi.server.UnicastRemoteObject;
	/**
	* Implementation of {@link CentralTimeService}
	*
	* User: smhumayun
	* Date: 7/4/13
	* Time: 8:25 AM
	*/
	public class CentralTimeServiceImpl extends UnicastRemoteObject implements CentralTimeService {
	/**
	* Creates and exports a new UnicastRemoteObject object using an
	* anonymous port.
	*
	* @throws java.rmi.RemoteException if failed to export object
	* @since JDK1.1
	*/
	protected CentralTimeServiceImpl() throws RemoteException {
	super(0,
	new SslRMIClientSocketFactory(),
	new SslRMIServerSocketFactory(null, null, true));
	}
	/**
	* Return current time in milliseconds on server
	*
	* @return current time on server in milliseconds
	* @throws RemoteException
	*/
	@Override
	public long getTime() throws RemoteException {
	return System.currentTimeMillis();
	}
	/**
	* Main method to start server
	*
	* @param args arguments
	*/
	public static void main(String args[]) {
	try {
	// Get SSL-based registry
	Registry registry = LocateRegistry.getRegistry(null, CentralTimeService.PORT, new SslRMIClientSocketFactory());
	//Create new impl object
	CentralTimeServiceImpl centralTimeServiceImpl = new CentralTimeServiceImpl();
	// Bind this object instance to the name "CentralTimeService"
	registry.bind("CentralTimeService", centralTimeServiceImpl);
	System.out.println("CentralTimeService bound in registry");
	} catch (Exception e) {
	System.out.println("CentralTimeServiceImpl Error : " + e.getMessage());
	e.printStackTrace();
	}
	}
	}

view raw CentralTimeServiceImpl.java hosted with ❤ by GitHub

Create RMI Client which will consume/invoke RMI method remotely

	/**
	* Java Remote Method Invocation (RMI) with Secure Socket Layer (SSL)
	* http://codeoftheday.blogspot.com/2013/07/java-remote-method-invocation-rmi-with.html
	*/
	package smhumayun.codeoftheday.RmiOverSslTest;
	import javax.rmi.ssl.SslRMIClientSocketFactory;
	import java.rmi.AccessException;
	import java.rmi.NotBoundException;
	import java.rmi.RemoteException;
	import java.rmi.registry.LocateRegistry;
	import java.rmi.registry.Registry;
	import java.text.SimpleDateFormat;
	import java.util.Date;
	/**
	* Client which consumes {@link CentralTimeService}
	*
	* User: smhumayun
	* Date: 7/4/13
	* Time: 8:34 AM
	*/
	public class CentralTimeServiceClient {
	public static void main(String args[]) {
	try {
	//Make reference to SSL-based registry
	Registry registry = LocateRegistry.getRegistry(null, CentralTimeService.PORT, new SslRMIClientSocketFactory());
	//Create a reference to the remote object that implements the "CentralTimeService"
	CentralTimeService centralTimeService = (CentralTimeService) registry.lookup("CentralTimeService");
	//Invoke RMI call
	long serverTime = centralTimeService.getTime();
	System.out.println("Central Server Time is " + SimpleDateFormat.getDateTimeInstance().format(new Date(serverTime)));
	} catch (AccessException e) {
	e.printStackTrace();
	} catch (RemoteException e) {
	e.printStackTrace();
	} catch (NotBoundException e) {
	e.printStackTrace();
	}
	}
	}

view raw CentralTimeServiceClient.java hosted with ❤ by GitHub

Finally, create RMI Registry

	/**
	* Java Remote Method Invocation (RMI) with Secure Socket Layer (SSL)
	* http://codeoftheday.blogspot.com/2013/07/java-remote-method-invocation-rmi-with.html
	*/
	package smhumayun.codeoftheday.RmiOverSslTest;
	import javax.rmi.ssl.SslRMIClientSocketFactory;
	import javax.rmi.ssl.SslRMIServerSocketFactory;
	import java.rmi.registry.LocateRegistry;
	/**
	* RMI Registry
	*
	* User: smhumayun
	* Date: 7/4/13
	* Time: 8:40 AM
	*/
	public class RmiRegistry {
	public static void main(String[] args) throws Exception
	{
	// Start RMI registry on configured port
	LocateRegistry.createRegistry(CentralTimeService.PORT, new SslRMIClientSocketFactory(), new SslRMIServerSocketFactory(null, null, true));
	System.out.println("RMI registry running on port " + CentralTimeService.PORT);
	// Sleep forever
	Thread.sleep(Long.MAX_VALUE);
	}
	}

view raw RmiRegistry.java hosted with ❤ by GitHub

Copy ‘test-keystore’ created here and ‘test-truststore’ created here to the folder where your compiled classes reside.

Now, open up a console/command prompt and ‘cd’ to the directory where your compiled class files are, and:

Run RMIRegistry

java -Djavax.net.ssl.keyStore=test-keystore -Djavax.net.ssl.keyStorePassword=test-keystore-pwd -Djavax.net.ssl.trustStore=test-truststore -Djavax.net.ssl.trustStorePassword=test-truststore-pwd smhumayun.codeoftheday.RmiOverSslTest.RmiRegistry

Run CentralTimeServiceImpl

java -Djavax.net.ssl.keyStore=test-keystore -Djavax.net.ssl.keyStorePassword=test-keystore-pwd -Djavax.net.ssl.trustStore=test-truststore -Djavax.net.ssl.trustStorePassword=test-truststore-pwd smhumayun.codeoftheday.RmiOverSslTest.CentralTimeServiceImpl

Run CentralTimeServiceClient

java -Djavax.net.ssl.keyStore=test-keystore -Djavax.net.ssl.keyStorePassword=test-keystore-pwd -Djavax.net.ssl.trustStore=test-truststore -Djavax.net.ssl.trustStorePassword=test-truststore-pwd smhumayun.codeoftheday.RmiOverSslTest.CentralTimeServiceClient

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