Java tutorial
/* * Copyright 2013 Jean-Francois Arcand * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */ package org.atmosphere.plugin.rabbitmq; import com.rabbitmq.client.AMQP; import com.rabbitmq.client.Channel; import com.rabbitmq.client.DefaultConsumer; import com.rabbitmq.client.Envelope; import com.rabbitmq.client.MessageProperties; import org.atmosphere.cpr.AtmosphereConfig; import org.atmosphere.cpr.BroadcasterFuture; import org.atmosphere.cpr.Entry; import org.atmosphere.util.SimpleBroadcaster; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; /** * Simple {@link org.atmosphere.cpr.Broadcaster} implementation based on RabbitMQ * * @author Thibault Normand * @author Jean-Francois Arcand */ public class RabbitMQBroadcaster extends SimpleBroadcaster { private static final Logger logger = LoggerFactory.getLogger(RabbitMQBroadcaster.class); private String queueName; private String consumerTag; private final RabbitMQConnectionFactory factory; private final Channel channel; private final String exchangeName; public RabbitMQBroadcaster(String id, AtmosphereConfig config) { super(id, config); factory = RabbitMQConnectionFactory.getFactory(config); channel = factory.channel(); exchangeName = factory.exchangeName(); } @Override public void setID(String id) { super.setID(id); restartConsumer(); } @Override public String getID() { String id = super.getID(); if (id.startsWith("/*")) { id = "atmosphere"; } return id; } @Override protected void push(Entry entry) { if (destroyed.get()) { return; } outgoingBroadcast(entry.message); } public void outgoingBroadcast(Object message) { try { String id = getID(); if (message instanceof String) { logger.trace("Outgoing broadcast : {}", message); channel.basicPublish(exchangeName, id, MessageProperties.PERSISTENT_TEXT_PLAIN, message.toString().getBytes()); } else { throw new IOException("Message is not a string, so could not be handled !"); } } catch (IOException e) { logger.warn("Failed to send message over RabbitMQ", e); } } void restartConsumer() { try { final String id = getID(); if (consumerTag != null) { logger.debug("Delete consumer {}", consumerTag); channel.basicCancel(consumerTag); consumerTag = null; } if (queueName != null) { logger.debug("Delete queue {}", queueName); channel.queueUnbind(queueName, exchangeName, id); channel.queueDelete(queueName); queueName = null; } queueName = channel.queueDeclare().getQueue(); channel.queueBind(queueName, exchangeName, id); logger.info("Create AMQP consumer on queue {}, for routing key {}", queueName, id); DefaultConsumer queueConsumer = new DefaultConsumer(channel) { @Override public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException { // Not for us. if (!envelope.getRoutingKey().equalsIgnoreCase(id)) return; String message = new String(body); try { Object newMsg = filter(message); // if newSgw == null, that means the message has been filtered. if (newMsg != null) { deliverPush(new Entry(newMsg, new BroadcasterFuture<Object>(newMsg, RabbitMQBroadcaster.this), message), true); } } catch (Throwable t) { logger.error("failed to push message: " + message, t); } } }; consumerTag = channel.basicConsume(queueName, true, queueConsumer); logger.info("Consumer " + consumerTag + " for queue {}, on routing key {}", queueName, id); } catch (Throwable ex) { String msg = "Unable to initialize RabbitMQBroadcaster"; logger.error(msg, ex); throw new IllegalStateException(msg, ex); } } @Override public synchronized void releaseExternalResources() { try { if (channel != null && channel.isOpen()) { if (consumerTag != null) { channel.basicCancel(consumerTag); } } } catch (Exception ex) { logger.trace("", ex); } } }