A simple JGroups demo

JGroupsDemo.java

package it.tgi.demos;

import org.jgroups.*;

import static it.tgi.demos.JGroupsDemo.Role.MASTER;
import static it.tgi.demos.JGroupsDemo.Role.SLAVE;

/**
 * Created by nanomad on 28/05/2017.
 */
public class JGroupsDemo extends ReceiverAdapter {

    private Role role;

    enum Role {
        MASTER,
        SLAVE
    }

    private final JChannel channel;

    public static void main(String[] args) throws Exception {
        new JGroupsDemo();
    }

    public JGroupsDemo() throws Exception {
        this.role = SLAVE;
        channel = new JChannel();
        channel.setReceiver(this);
        channel.connect("Ze Cluster");
    }

    @Override
    public void viewAccepted(View view) {
        System.out.println("New view " + view.toString());
        Address coordinator = view.getCoord();
        if (coordinator.equals(channel.getAddress())) {
            switch (role) {
                case SLAVE:
                    System.err.println(channel.getClusterName() + " I'm your master, now");
                    this.role = MASTER;
                    break;
                case MASTER:
                    break;
                default:
                    throw new IllegalStateException("Role not supported: " + role);
            }
        } else {
            switch (role) {
                case MASTER:
                    System.err.println("Uh-oh, we lost master status! Our lord now is " + coordinator);
                    break;
                case SLAVE:
                    break;
                default:
                    throw new IllegalStateException("Role not supported: " + role);
            }
        }
    }

    @Override
    public void receive(Message msg) {
        System.out.println("Got message " + msg.getObject());
    }
}