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A simple pub-sub library on top of the RabbitMQ infrastructure.

There is a newer version: 0.1-RELEASE

package org.bitbucket.gkutiel;

import static org.slf4j.LoggerFactory.getLogger;
import java.io.IOException;
import org.slf4j.Logger;
import com.google.gson.Gson;
import com.rabbitmq.client.AMQP.BasicProperties;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;

class Bus {
	private final Channel channel = openChannel();
	private final String EXCHANGE = "default";
	private final Gson gson = new Gson();
	private final Logger log = getLogger(Bus.class);

	private  void addConsumer(final Class type, final Callback on, final String name) throws IOException {
		final DefaultConsumer consumer = new DefaultConsumer(channel) {
			@Override public void handleDelivery(final String tag, final Envelope env, final BasicProperties props,
					final byte[] body) throws IOException {
				on.event(gson.fromJson(new String(body), type));
			}
		};
		channel.basicConsume(name, consumer);
	}

	private Channel openChannel() {
		try {
			final ConnectionFactory factory = new ConnectionFactory();
			factory.setHost("localhost");
			final Channel c = factory.newConnection().createChannel();
			c.exchangeDeclare(EXCHANGE, "direct");
			return c;
		} catch (final IOException e) {
			throw new RuntimeException(e);
		}
	}

	 void pub(final String channelName, final T val) {
		try {
			final String json = gson.toJson(val);
			log.info("pub event key {} val {}", channelName, json);
			channel.basicPublish(EXCHANGE, channelName, null, json.getBytes("utf-8"));
		} catch (final IOException e) {
			throw new RuntimeException(e);
		}
	}

	 void sub(final String channelName, final Class type, final Callback on) {
		try {
			final String name = channel.queueDeclare().getQueue();
			channel.queueBind(name, EXCHANGE, channelName);
			addConsumer(type, on, name);
		} catch (final IOException e) {
			throw new RuntimeException(e);
		}
	}
}