Creating a Java RMI Server

kc@example.com (kc kim) — Tue, 29 Mar 2022 08:14:00 +0900

RMI

Java RMI (Remote Method Invocation) is a protocol that enables message transmission, including method calls, between distributed objects.
With RMI, you can build a server very simply without having to think about sockets.
You can also access the server almost as if you were using a local class.

To start the server, add permission java.security.AllPermission; to JAVA_HOME/jre/lib/security/java.policy.

Server interface

package com.devkuma.basic.rmi;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface RemoteServer extends Remote {
    boolean isAlive() throws RemoteException;
}

Server implementation class

package com.devkuma.basic.rmi;

import java.net.MalformedURLException;
import java.rmi.Naming;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.server.UnicastRemoteObject;

public class RemoteServerImpl extends UnicastRemoteObject implements RemoteServer {

    public RemoteServerImpl(String name, int port) throws RemoteException {
        System.setSecurityManager(new SecurityManager());
        LocateRegistry.createRegistry(port);
        try {
            Naming.rebind(new StringBuffer(64).append("//:").append(port)
                    .append('/').append(name).toString(), this);
        } catch (MalformedURLException e) {
            throw new RemoteException(e.getMessage(), e);
        }
    }

    public boolean isAlive() throws RemoteException {
        return true;
    }

    public static void main(String[] args) {
        try {
            String serviceName = "devkuma";
            int port = 1234;
            new RemoteServerImpl(serviceName, port);
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }
}

Client class

package com.devkuma.basic.rmi;

import java.rmi.Naming;

public class RemoteServerClient {

    public static void main(String[] args) {
        try {
            RemoteServer server = (RemoteServer) Naming.lookup("rmi:/localhost:1234/devkuma");
            System.out.println(server.isAlive());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

devkuma – RMI

Creating a Java RMI Server

RMI