RabbitMQ

Info

I love it...

After years of working with CORBA and not really seeing anything much on the market to replace, I was forced to look at an alternative the WebServices using a ReSTful api called Jersey - absolute nightmare to work it. It turns a simple task of marshalling complex objects across the wire in an Eaton Mess. It's a mishmash of code that just doesn't work properly, is hard to debug and test.

I've been familiar with MOM based technologies since the 1990s (DDE, JMS, MS-MQ, MQ-Series etc). I had heard about RabbitMQ some time ago but never actually used. So when I decided to get my teeth into, I was shocked how easy it was to deploy and work. It's elegant and easy to work with.

I'm working with the pub/sub model. The examples given in the RabbitMQ documentation pretty much outline the code as follows

Publisher

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.Channel;

public class RabbitMqLogsSender
{
    private static String EXCHANGE_NAME = "logs"; // specify as ReSTful URI param
    private static final String HOST_ID = "192.168.99.100"; // put in a config file

    public static void main(String[] argv) throws Exception
    {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost(HOST_ID);   // put this in a config file
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.FANOUT);

        String message = argv[0];

        channel.basicPublish(EXCHANGE_NAME, "", null, message.getBytes("UTF-8"));
        System.out.println(" [x] Sent '" + message + "'");

        channel.close();
        connection.close();
    }

Subscriber

import com.rabbitmq.client.*;

import java.io.IOException;

public class RabbitMqLogsReceiver
{
    private static String EXCHANGE_NAME = "logs";
    private static final String HOST_ID = "192.168.99.100";

    public static void main(String[] argv) throws Exception
    {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost(HOST_ID);
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.FANOUT);
        String queueName = channel.queueDeclare().getQueue();
        channel.queueBind(queueName, EXCHANGE_NAME, "");
        
        // Once a channel has been created, yu can send messages to yourself on it...
        String message = "Sending a message to myself to start";
        channel.basicPublish(EXCHANGE_NAME, "", null, message.getBytes("UTF-8"));

        System.out.println(" [*] Waiting for messages on: " + queueName + ". To exit press CTRL+C");

        Consumer consumer = new DefaultConsumer(channel)
        {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope,
                    AMQP.BasicProperties properties, byte[] body) throws IOException
            {
                String message = new String(body, "UTF-8");
                System.out.println(" [x] Received '" + message + "'");
            }
        };
        channel.basicConsume(queueName, true, consumer);
    }
}