source: trunk/src/main/java/omq/common/broker/Broker.java @ 83

package omq.common.broker;

import java.io.IOException;
import java.lang.reflect.Proxy;
import java.net.URL;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;
import java.util.Properties;

import omq.Remote;
import omq.client.listener.ResponseListener;
import omq.client.proxy.MultiProxymq;
import omq.client.proxy.Proxymq;
import omq.common.util.OmqConnectionFactory;
import omq.common.util.ParameterQueue;
import omq.common.util.Serializer;
import omq.exception.AlreadyBoundException;
import omq.exception.InitBrokerException;
import omq.exception.RemoteException;
import omq.server.RemoteObject;

import org.apache.log4j.Logger;
import org.apache.log4j.xml.DOMConfigurator;

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;

/**
 * A "broker" allows a new connection to a RabbitMQ server. Under this
 * connection it can have binded object and proxies.
 * 
 * @author Sergi Toda <sergi.toda@estudiants.urv.cat>
 * 
 */
public class Broker {

        private static final Logger logger = Logger.getLogger(Broker.class.getName());

        private Connection connection;
        private Channel channel;
        private ResponseListener responseListener;
        private Serializer serializer;
        private boolean clientStarted = false;
        private boolean connectionClosed = false;
        private Properties environment = null;
        private Map<String, RemoteObject> remoteObjs;
        private Map<String, Object> proxies = new Hashtable<String, Object>();
        private Map<String, Object> multiProxies = new Hashtable<String, Object>();

        public Broker(Properties env) throws Exception {
                // Load log4j configuration
                URL log4jResource = Broker.class.getResource("/log4j.xml");
                DOMConfigurator.configure(log4jResource);

                remoteObjs = new HashMap<String, RemoteObject>();
                serializer = new Serializer(env);
                environment = 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");
                }
        }

        /**
         * This method stops the broker's connection and all the threads created
         * 
         * @throws Exception
         */
        public void stopBroker() throws Exception {
                logger.warn("Stopping broker");
                // Stop the client
                if (clientStarted) {
                        responseListener.kill();
                        // TODO proxies = null; ??
                }
                // Stop all the remote objects working
                for (String reference : remoteObjs.keySet()) {
                        unbind(reference);
                }

                // Close the connection once all the listeners are died
                closeConnection();

                clientStarted = false;
                connectionClosed = false;
                environment = null;
                remoteObjs = null;
        }

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

        /**
         * This method close the broker's connection
         * 
         * @throws IOException
         */
        public void closeConnection() throws IOException {
                logger.warn("Clossing connection");
                connectionClosed = true;
                connection.close();
                connectionClosed = false;
        }

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

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

        /**
         * Returns the remote object for specified reference.
         * 
         * @param reference
         *            - Binding name
         * @param contract
         *            - Remote Interface
         * @return newProxy
         * @throws RemoteException
         */
        @SuppressWarnings("unchecked")
        public synchronized <T extends Remote> T lookup(String reference, Class<T> contract) throws RemoteException {
                try {

                        if (!clientStarted) {
                                initClient();
                        }

                        if (!proxies.containsKey(reference)) {
                                Proxymq proxy = new Proxymq(reference, contract, this);
                                Class<?>[] array = { contract };
                                Object newProxy = Proxy.newProxyInstance(contract.getClassLoader(), array, proxy);
                                proxies.put(reference, newProxy);
                                return (T) newProxy;
                        }
                        return (T) proxies.get(reference);

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

        /**
         * Returns the remote object for specified reference. This function returns
         * an special type of proxy, every method invoked will be multi and
         * asynchronous.
         * 
         * @param reference
         *            - Binding name
         * @param contract
         *            - Remote Interface
         * @return newProxy
         * @throws RemoteException
         */
        @SuppressWarnings("unchecked")
        public synchronized <T extends Remote> T lookupMulti(String reference, Class<T> contract) throws RemoteException {
                try {
                        if (!multiProxies.containsKey(reference)) {
                                MultiProxymq proxy = new MultiProxymq(reference, contract, this);
                                Class<?>[] array = { contract };
                                Object newProxy = Proxy.newProxyInstance(contract.getClassLoader(), array, proxy);
                                multiProxies.put(reference, newProxy);
                                return (T) newProxy;
                        }
                        return (T) multiProxies.get(reference);

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

        /**
         * Binds the reference to the specified remote object. This function uses
         * the broker's environment
         * 
         * @param reference
         *            - Binding name
         * @param remote
         *            - RemoteObject to bind
         * @throws RemoteException
         *             If the remote operation failed
         * @throws AlreadyBoundException
         *             If name is already bound.
         */
        public void bind(String reference, RemoteObject remote) throws RemoteException, AlreadyBoundException {
                bind(reference, remote, environment);
        }

        /**
         * Binds the reference to the specified remote object. This function uses
         * the broker's environment
         * 
         * @param reference
         *            - Binding name
         * @param remote
         *            - RemoteObject to bind
         * @param env
         *            - RemoteObject environment. You can set how many threads will
         *            be listen to the reference, the multiqueue name and the
         *            properties of the object queue and multiqueue
         * @throws RemoteException
         *             If the remote operation failed
         * @throws AlreadyBoundException
         *             If name is already bound.
         */
        public void bind(String reference, RemoteObject remote, Properties env) throws RemoteException, AlreadyBoundException {
                if (remoteObjs.containsKey(reference)) {
                        throw new AlreadyBoundException(reference);
                }
                // Try to start the remtoeObject listeners
                try {
                        remote.startRemoteObject(reference, this, env);
                        remoteObjs.put(reference, remote);
                } catch (Exception e) {
                        throw new RemoteException(e);
                }
        }

        /**
         * Unbinds a remoteObject from its reference and kills all the threads
         * created.
         * 
         * @param reference
         *            - Binding name
         * @throws RemoteException
         *             If the remote operation failed
         * @throws IOException
         *             If there are problems while killing the threads
         */
        public 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");
                }

        }

        /**
         * This method ensures the client will have only one ResponseListener.
         * 
         * @throws Exception
         */
        private synchronized void initClient() throws Exception {
                if (responseListener == null) {
                        responseListener = new ResponseListener(this);
                        responseListener.start();
                        clientStarted = true;
                }
        }

        /**
         * This function is used to send a ping message to see if the connection
         * works
         * 
         * @param env
         * @throws Exception
         */
        public 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 void addFaultTolerance() {
                connection.addShutdownListener(new ShutdownListener() {
                        @Override
                        public void shutdownCompleted(ShutdownSignalException cause) {
                                logger.warn("Shutdown message received. Cause: " + cause.getMessage());
                                if (!connectionClosed)
                                        if (cause.isHardError()) {
                                                if (connection.isOpen()) {
                                                        try {
                                                                connection.close();
                                                        } catch (IOException e) {
                                                                e.printStackTrace();
                                                        }
                                                }
                                                try {
                                                        connection = OmqConnectionFactory.getNewWorkingConnection(environment);
                                                        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();
                                                        }
                                                }
                                        }
                        }
                });
        }

        public Properties getEnvironment() {
                return environment;
        }

        public ResponseListener getResponseListener() {
                return responseListener;
        }

        public Serializer getSerializer() {
                return serializer;
        }
}