source: branches/objectmq_old/src/omq/common/broker/Broker.java

package omq.common.broker;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

import omq.Remote;
import omq.client.listener.ResponseListener;
import omq.client.proxy.Proxymq;
import omq.common.event.Event;
import omq.common.event.EventDispatcher;
import omq.common.event.EventWrapper;
import omq.common.util.Environment;
import omq.common.util.OmqConnectionFactory;
import omq.common.util.ParameterQueue;
import omq.common.util.Serializer;
import omq.exception.InitBrokerException;
import omq.exception.RemoteException;
import omq.exception.SerializerException;
import omq.server.RemoteObject;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.QueueingConsumer;
import com.rabbitmq.client.QueueingConsumer.Delivery;
import com.rabbitmq.client.ShutdownListener;
import com.rabbitmq.client.ShutdownSignalException;

public class Broker {
        private static Connection connection;
        private static Channel channel;
        private static boolean clientStarted = false;
        private static boolean connectionClosed = false;
        // TODO ask Pedro if it can be only one object in the map (an object can
        // have multiple threads in the same broker -see environment-)
        private static Map<String, RemoteObject> remoteObjs;

        /**
         * Initializes a new Broker with the environment called by reference
         * 
         * @param env
         * @throws Exception
         */
        public static synchronized void initBroker(Properties env) throws Exception {
                if (Environment.isVoid()) {
                        remoteObjs = new HashMap<String, RemoteObject>();
                        Environment.setEnvironment(env);
                        connection = OmqConnectionFactory.getNewConnection(env);
                        channel = connection.createChannel();
                        addFaultTolerance();
                        try {
                                tryConnection(env);
                        } catch (Exception e) {
                                channel.close();
                                connection.close();
                                throw new InitBrokerException("The connection didn't work");
                        }
                } else {
                        throw new InitBrokerException("Broker already started");
                }
        }

        public static void stopBroker() throws Exception {
                // Stop the client
                if (clientStarted) {
                        ResponseListener.stopResponseListner();
                        EventDispatcher.stopEventDispatcher();
                }
                // Stop all the remote objects working
                for (String reference : remoteObjs.keySet()) {
                        unbind(reference);
                }
                // Close the connection once all the listeners are died
                closeConnection();
        }

        /**
         * @return Broker's connection
         * @throws Exception
         */
        public static Connection getConnection() throws Exception {
                return connection;
        }

        public static void closeConnection() throws IOException {
                connectionClosed = true;
                connection.close();
        }

        /**
         * 
         * @return Broker's channel
         * @throws Exception
         */
        public static Channel getChannel() throws Exception {
                return channel;
        }

        /**
         * Creates a new channel using the Broker's connection
         * 
         * @return newChannel
         * @throws IOException
         */
        public static Channel getNewChannel() throws IOException {
                return connection.createChannel();
        }

        @SuppressWarnings("unchecked")
        public static <T extends Remote> T lookup(String reference, Class<T> contract) throws RemoteException {
                try {
                        Properties environment = Environment.getEnvironment();

                        if (!clientStarted) {
                                initClient(environment);
                                clientStarted = true;
                        }

                        if (!Proxymq.containsProxy(reference)) {
                                Proxymq proxy = new Proxymq(reference, contract, environment);
                                Class<?>[] array = { contract };
                                return (T) Proxymq.newProxyInstance(contract.getClassLoader(), array, proxy);
                        }
                        return (T) Proxymq.getInstance(reference);

                } catch (Exception e) {
                        throw new RemoteException(e);
                }
        }

        public static void bind(String reference, RemoteObject remote) throws RemoteException {
                try {
                        Properties environment = Environment.getEnvironment();
                        remote.startRemoteObject(reference, environment);
                        remoteObjs.put(reference, remote);
                } catch (Exception e) {
                        throw new RemoteException(e);
                }
        }

        public static void unbind(String reference) throws RemoteException, IOException {
                if (remoteObjs.containsKey(reference)) {
                        RemoteObject remote = remoteObjs.get(reference);
                        remote.kill();
                } else {
                        throw new RemoteException("The object referenced by 'reference' does not exist in the Broker");
                }

        }

        public void rebind(String name, Remote obj) throws RemoteException {

        }

        /**
         * This method ensures the client will have only one ResponseListener and
         * only one EventDispatcher. Both with the same environment.
         * 
         * @param environment
         * @throws Exception
         */
        private static synchronized void initClient(Properties environment) throws Exception {
                if (ResponseListener.isVoid()) {
                        ResponseListener.init(environment);
                }
                if (EventDispatcher.isVoid()) {
                        EventDispatcher.init(environment);
                }
        }

        /**
         * This method sends an event with its information
         * 
         * @param event
         * @throws IOException
         * @throws SerializerException
         */
        public static void trigger(Event event) throws IOException, SerializerException {
                String UID = event.getTopic();
                EventWrapper wrapper = new EventWrapper(event);
                System.out.println("EventTrigger fanout exchange: " + UID + " Event topic: " + UID + " Event corrID: " + event.getCorrId());
                channel.exchangeDeclare(UID, "fanout");

                byte[] bytesResponse = Serializer.serialize(wrapper);
                channel.basicPublish(UID, "", null, bytesResponse);

                // Log.saveLog("Server-Serialize", bytesResponse);
        }

        /**
         * This function is used to send a ping message to see if the connection
         * works
         * 
         * @param env
         * @throws Exception
         */
        public static void tryConnection(Properties env) throws Exception {
                Channel channel = connection.createChannel();
                String message = "ping";

                String exchange = env.getProperty(ParameterQueue.USER_NAME) + "ping";
                String queueName = exchange;
                String routingKey = "routingKey";

                channel.exchangeDeclare(exchange, "direct");
                channel.queueDeclare(queueName, false, false, false, null);
                channel.queueBind(queueName, exchange, routingKey);

                channel.basicPublish(exchange, routingKey, null, message.getBytes());

                QueueingConsumer consumer = new QueueingConsumer(channel);

                channel.basicConsume(queueName, true, consumer);
                Delivery delivery = consumer.nextDelivery(1000);

                channel.exchangeDelete(exchange);
                channel.queueDelete(queueName);

                channel.close();

                if (!message.equalsIgnoreCase(new String(delivery.getBody()))) {
                        throw new IOException("Ping initialitzation has failed");
                }
        }

        /**
         * This method adds a ShutdownListener to the Broker's connection. When this
         * connection falls, a new connection will be created and this will also
         * have the listener.
         */
        private static void addFaultTolerance() {
                connection.addShutdownListener(new ShutdownListener() {
                        @Override
                        public void shutdownCompleted(ShutdownSignalException cause) {
                                if (!connectionClosed)
                                        if (cause.isHardError()) {
                                                if (connection.isOpen()) {
                                                        try {
                                                                connection.close();
                                                        } catch (IOException e) {
                                                                e.printStackTrace();
                                                        }
                                                }
                                                try {
                                                        Properties env = Environment.getEnvironment();
                                                        connection = OmqConnectionFactory.getNewWorkingConnection(env);
                                                        channel = connection.createChannel();
                                                        addFaultTolerance();
                                                } catch (Exception e) {
                                                        e.printStackTrace();
                                                }
                                        } else {
                                                Channel channel = (Channel) cause.getReference();
                                                if (channel.isOpen()) {
                                                        try {
                                                                channel.close();
                                                        } catch (IOException e) {
                                                                e.printStackTrace();
                                                        }
                                                }
                                        }
                        }
                });
        }

}