Simple text-based chat application (SimpleChat), with the following features:

SimpleChat.java

package com.simpleChat;
import org.jgroups.*;

import java.io.BufferedReader;
import java.io.InputStreamReader;

// Reference: http://www.jgroups.org/tutorial/#_configuration
public class SimpleChat extends ReceiverAdapter{
    /*
    * JGroups uses a JChannel as the main API to connect to a cluster, send and receive messages, and to register
    * listeners that are called when things (such as member joins) happen.
    */
    JChannel channel;
    String userName = "";

    private void start(String userName) throws Exception {
        // Alternatively, we could pass an XML file to configure the channel, e.g. new JChannel("/home/bela/udp.xml").
        channel = new JChannel(); // use default config, udp.xml
        channel.receiver(this);
        this.userName = userName;

        /*
         * Note that we don’t need to explicitly create a cluster beforehand; connect() creates the cluster if it is the
         * first instance.
        */
        channel.connect("ChatCluster"); // Joins cluster "ChatCluster"
        eventLoop();
        channel.close();
    }

    /**
     * Callback is called whenever a new instance joins the cluster, or an existing instance leaves (crashes included).
     * Its
     */
    public void viewAccepted(View view) {
        System.out.println("** view: " + view);
    }

    /**
     * We simply get its buffer as an object (again using Java serialization) and print it to stdout. We also print
     * the sender’s address (Message.getSrc()).
     */
    public void receive(Message message) {
        System.out.println(message.getSrc() + ": " + message.getObject());
    }

    /*
     * We now run an event loop, which reads input from stdin (a message) and sends it to all instances currently in the
     * cluster. When "exit" or "quit" are entered, we fall out of the loop and close the channel.
    */
    private void eventLoop() {
        InputStreamReader inputStreamReader = new InputStreamReader(System.in);
        BufferedReader input = new BufferedReader(inputStreamReader);

        while(true) {
            try {
                System.out.println("> ");
                System.out.flush();
                String line = input.readLine();

                if(line.startsWith("quit") || line.startsWith("exit")) break;

                line = "["+userName+"]"+ line;
                /*
                 * Message constructor
                 * First argument is the destination address
                 *  |> A null destination address sends the message to everyone
                 *
                 * First argument is the source address
                 *  |> This is null as well, as the stack will insert the correct address anyway.
                 *
                 */
                Message message = new Message(null, null, line);
                channel.send(message);
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }
        }
    }

    public static void main(String[] args) throws Exception  {
        new SimpleChat().start(args[0]);
    }
}