/**
 *   GRANITE DATA SERVICES
 *   Copyright (C) 2006-2013 GRANITE DATA SERVICES S.A.S.
 *
 *   This file is part of the Granite Data Services Platform.
 *
 *   Granite Data Services is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   Granite Data Services is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
 *   General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 *   USA, or see <http://www.gnu.org/licenses/>.
 */
package org.granite.gravity;

import java.io.Serializable;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.ConcurrentHashMap;

import javax.management.ObjectName;

import org.granite.clustering.DistributedData;
import org.granite.config.GraniteConfig;
import org.granite.config.flex.Destination;
import org.granite.config.flex.ServicesConfig;
import org.granite.context.GraniteContext;
import org.granite.context.SimpleGraniteContext;
import org.granite.gravity.adapters.AdapterFactory;
import org.granite.gravity.adapters.ServiceAdapter;
import org.granite.gravity.security.GravityDestinationSecurizer;
import org.granite.gravity.security.GravityInvocationContext;
import org.granite.gravity.udp.UdpReceiverFactory;
import org.granite.jmx.MBeanServerLocator;
import org.granite.jmx.OpenMBean;
import org.granite.logging.Logger;
import org.granite.messaging.amf.process.AMF3MessageInterceptor;
import org.granite.messaging.jmf.SharedContext;
import org.granite.messaging.service.security.SecurityService;
import org.granite.messaging.service.security.SecurityServiceException;
import org.granite.messaging.webapp.ServletGraniteContext;
import org.granite.scan.ServiceLoader;
import org.granite.util.TypeUtil;
import org.granite.util.UUIDUtil;

import flex.messaging.messages.AcknowledgeMessage;
import flex.messaging.messages.AsyncMessage;
import flex.messaging.messages.CommandMessage;
import flex.messaging.messages.ErrorMessage;
import flex.messaging.messages.Message;

/**
 * @author William DRAI
 * @author Franck WOLFF
 */
public class DefaultGravity implements Gravity, DefaultGravityMBean {

    ///////////////////////////////////////////////////////////////////////////
    // Fields.

    private static final Logger log = Logger.getLogger(Gravity.class);

    private final Map<String, Object> applicationMap = new HashMap<String, Object>();
    private final ConcurrentHashMap<String, TimeChannel<?>> channels = new ConcurrentHashMap<String, TimeChannel<?>>();
    
    private GravityConfig gravityConfig = null;
    private ServicesConfig servicesConfig = null;
    private GraniteConfig graniteConfig = null;
    private SharedContext sharedContext = null;

    private Channel serverChannel = null;
    private AdapterFactory adapterFactory = null;
    private GravityPool gravityPool = null;
    
    private UdpReceiverFactory udpReceiverFactory = null;

    private Timer channelsTimer;
    private boolean started;

    ///////////////////////////////////////////////////////////////////////////
    // Constructor.

    public DefaultGravity(GravityConfig gravityConfig, ServicesConfig servicesConfig, GraniteConfig graniteConfig, SharedContext sharedContext) {
        if (gravityConfig == null || servicesConfig == null || graniteConfig == null)
            throw new NullPointerException("All arguments must be non null.");

        this.gravityConfig = gravityConfig;
        this.servicesConfig = servicesConfig;
        this.graniteConfig = graniteConfig;
        this.sharedContext = sharedContext;
    }

    ///////////////////////////////////////////////////////////////////////////
    // Properties.

    public GravityConfig getGravityConfig() {
                return gravityConfig;
        }

        public ServicesConfig getServicesConfig() {
        return servicesConfig;
    }

        public GraniteConfig getGraniteConfig() {
        return graniteConfig;
    }

    public SharedContext getSharedContext() {
        return sharedContext;
    }

        public boolean isStarted() {
        return started;
    }
        
        public ServiceAdapter getServiceAdapter(String messageType, String destinationId) {
                return adapterFactory.getServiceAdapter(messageType, destinationId);
        }

    ///////////////////////////////////////////////////////////////////////////
    // Starting/stopping.

    public void start() throws Exception {
        log.info("Starting Gravity...");
        synchronized (this) {
                if (!started) {
                    adapterFactory = new AdapterFactory(this);
                    internalStart();
                    serverChannel = new ServerChannel(this, ServerChannel.class.getName(), null, null);
                    
                    if (gravityConfig.isUseUdp()) {
                        ServiceLoader<UdpReceiverFactory> loader = ServiceLoader.load(UdpReceiverFactory.class);
                        Iterator<UdpReceiverFactory> factories = loader.iterator();
                        if (factories.hasNext()) {
                                udpReceiverFactory = factories.next();
                                udpReceiverFactory.setPort(gravityConfig.getUdpPort());
                                udpReceiverFactory.setNio(gravityConfig.isUdpNio());
                                udpReceiverFactory.setConnected(gravityConfig.isUdpConnected());
                                udpReceiverFactory.setSendBufferSize(gravityConfig.getUdpSendBufferSize());
                                udpReceiverFactory.start();
                        }
                        else
                                log.warn("UDP receiver factory not found");
                    }
                    
                    started = true;
                }
        }
        log.info("Gravity successfully started.");
    }
    
    protected void internalStart() {
        gravityPool = new GravityPool(gravityConfig);
        channelsTimer = new Timer();
        
        if (graniteConfig.isRegisterMBeans()) {
                try {
                    ObjectName name = new ObjectName("org.graniteds:type=Gravity,context=" + graniteConfig.getMBeanContextName());
                        log.info("Registering MBean: %s", name);
                    OpenMBean mBean = OpenMBean.createMBean(this);
                        MBeanServerLocator.getInstance().register(mBean, name, true);
                }
                catch (Exception e) {
                        log.error(e, "Could not register Gravity MBean for context: %s", graniteConfig.getMBeanContextName());
                }
        }
    }
    
    public void restart() throws Exception {
        synchronized (this) {
                stop();
                start();
        }
        }

        public void reconfigure(GravityConfig gravityConfig, GraniteConfig graniteConfig) {
        this.gravityConfig = gravityConfig;
        this.graniteConfig = graniteConfig;
        if (gravityPool != null)
                gravityPool.reconfigure(gravityConfig);
    }

    public void stop() throws Exception {
        stop(true);
    }

    public void stop(boolean now) throws Exception {
        log.info("Stopping Gravity (now=%s)...", now);
        synchronized (this) {
                if (adapterFactory != null) {
                    try {
                                        adapterFactory.stopAll();
                                } catch (Exception e) {
                                log.error(e, "Error while stopping adapter factory");
                                }
                    adapterFactory = null;
                }

                if (serverChannel != null) {
                    try {
                                        removeChannel(serverChannel.getId(), false);
                                } catch (Exception e) {
                                log.error(e, "Error while removing server channel: %s", serverChannel);
                                }
                    serverChannel = null;
                }
            
            if (channelsTimer != null) {
                    try {
                                        channelsTimer.cancel();
                                } catch (Exception e) {
                                log.error(e, "Error while cancelling channels timer");
                                }
                    channelsTimer = null;
            }
                
                if (gravityPool != null) {
                        try {
                                if (now)
                                        gravityPool.shutdownNow();
                                else
                                        gravityPool.shutdown();
                        }
                        catch (Exception e) {
                                log.error(e, "Error while stopping thread pool");
                        }
                        gravityPool = null;
                }
                
                if (udpReceiverFactory != null) {
                        try {
                                udpReceiverFactory.stop();
                        }
                        catch (Exception e) {
                                log.error(e, "Error while stopping udp receiver factory");
                        }
                        udpReceiverFactory = null;
                }
            
            started = false;
        }
        log.info("Gravity sucessfully stopped.");
    }

    ///////////////////////////////////////////////////////////////////////////
    // GravityMBean attributes implementation.

        public String getGravityFactoryName() {
                return gravityConfig.getGravityFactory();
        }

        public long getChannelIdleTimeoutMillis() {
                return gravityConfig.getChannelIdleTimeoutMillis();
        }
        public void setChannelIdleTimeoutMillis(long channelIdleTimeoutMillis) {
                gravityConfig.setChannelIdleTimeoutMillis(channelIdleTimeoutMillis);
        }

        public boolean isRetryOnError() {
                return gravityConfig.isRetryOnError();
        }
        public void setRetryOnError(boolean retryOnError) {
                gravityConfig.setRetryOnError(retryOnError);
        }

        public long getLongPollingTimeoutMillis() {
                return gravityConfig.getLongPollingTimeoutMillis();
        }
        public void setLongPollingTimeoutMillis(long longPollingTimeoutMillis) {
                gravityConfig.setLongPollingTimeoutMillis(longPollingTimeoutMillis);
        }

        public int getMaxMessagesQueuedPerChannel() {
                return gravityConfig.getMaxMessagesQueuedPerChannel();
        }
        public void setMaxMessagesQueuedPerChannel(int maxMessagesQueuedPerChannel) {
                gravityConfig.setMaxMessagesQueuedPerChannel(maxMessagesQueuedPerChannel);
        }

        public long getReconnectIntervalMillis() {
                return gravityConfig.getReconnectIntervalMillis();
        }

        public int getReconnectMaxAttempts() {
                return gravityConfig.getReconnectMaxAttempts();
        }

    public int getCorePoolSize() {
        if (gravityPool != null)
                return gravityPool.getCorePoolSize();
        return gravityConfig.getCorePoolSize();
        }

        public void setCorePoolSize(int corePoolSize) {
                gravityConfig.setCorePoolSize(corePoolSize);
                if (gravityPool != null)
                gravityPool.setCorePoolSize(corePoolSize);
        }

        public long getKeepAliveTimeMillis() {
        if (gravityPool != null)
                return gravityPool.getKeepAliveTimeMillis();
        return gravityConfig.getKeepAliveTimeMillis();
        }
        public void setKeepAliveTimeMillis(long keepAliveTimeMillis) {
                gravityConfig.setKeepAliveTimeMillis(keepAliveTimeMillis);
                if (gravityPool != null)
                gravityPool.setKeepAliveTimeMillis(keepAliveTimeMillis);
        }

        public int getMaximumPoolSize() {
        if (gravityPool != null)
                return gravityPool.getMaximumPoolSize();
        return gravityConfig.getMaximumPoolSize();
        }
        public void setMaximumPoolSize(int maximumPoolSize) {
                gravityConfig.setMaximumPoolSize(maximumPoolSize);
                if (gravityPool != null)
                gravityPool.setMaximumPoolSize(maximumPoolSize);
        }

        public int getQueueCapacity() {
        if (gravityPool != null)
                return gravityPool.getQueueCapacity();
        return gravityConfig.getQueueCapacity();
        }

        public int getQueueRemainingCapacity() {
        if (gravityPool != null)
                return gravityPool.getQueueRemainingCapacity();
        return gravityConfig.getQueueCapacity();
        }

        public int getQueueSize() {
        if (gravityPool != null)
                return gravityPool.getQueueSize();
        return 0;
        }
        
        public boolean hasUdpReceiverFactory() {
                return udpReceiverFactory != null;
        }

    public UdpReceiverFactory getUdpReceiverFactory() {
                return udpReceiverFactory;
        }

    ///////////////////////////////////////////////////////////////////////////
    // Channel's operations.

        protected <C extends Channel> C createChannel(ChannelFactory<C> channelFactory, String clientId) {
        C channel = null;
        if (clientId != null) {
                channel = getChannel(channelFactory, clientId);
                if (channel != null)
                        return channel;
        }
        
        String clientType = GraniteContext.getCurrentInstance().getClientType();
        channel = channelFactory.newChannel(UUIDUtil.randomUUID(), clientType);
        TimeChannel<C> timeChannel = new TimeChannel<C>(channel);
        for (int i = 0; channels.putIfAbsent(channel.getId(), timeChannel) != null; i++) {
            if (i >= 10)
                throw new RuntimeException("Could not find random new clientId after 10 iterations");
            channel.destroy(false);
            channel = channelFactory.newChannel(UUIDUtil.randomUUID(), clientType);
            timeChannel = new TimeChannel<C>(channel);
        }

        String channelId = channel.getId();
        
        // Save channel id in distributed data (clustering).
        try {
                DistributedData gdd = graniteConfig.getDistributedDataFactory().getInstance();
                if (gdd != null) {
                        log.debug("Saving channel id in distributed data: %s", channelId);
                        gdd.addChannelId(channelId, channelFactory.getClass().getName(), clientType);
                }
        }
        catch (Exception e) {
                        log.error(e, "Could not add channel id in distributed data: %s", channelId);
        }
        
        // Initialize timer task.
        access(channelId);
        
        return channel;
    }

    @SuppressWarnings("unchecked")
        public <C extends Channel> C getChannel(ChannelFactory<C> channelFactory, String clientId) {
        if (clientId == null)
            return null;

                TimeChannel<C> timeChannel = (TimeChannel<C>)channels.get(clientId);
        if (timeChannel == null) {
                // Look for existing channel id/subscriptions in distributed data (clustering).
                try {
                        DistributedData gdd = graniteConfig.getDistributedDataFactory().getInstance();
                        if (gdd != null && gdd.hasChannelId(clientId)) {
                                log.debug("Found channel id in distributed data: %s", clientId);
                                String channelFactoryClassName = gdd.getChannelFactoryClassName(clientId);
                    String clientType = gdd.getChannelClientType(clientId);
                                channelFactory = (ChannelFactory<C>)TypeUtil.newInstance(channelFactoryClassName, new Class<?>[] { Gravity.class }, new Object[] { this });
                                C channel = channelFactory.newChannel(clientId, clientType);
                        timeChannel = new TimeChannel<C>(channel);
                        if (channels.putIfAbsent(clientId, timeChannel) == null) {
                                for (CommandMessage subscription : gdd.getSubscriptions(clientId)) {
                                        log.debug("Resubscribing channel: %s - %s", clientId, subscription);
                                        handleSubscribeMessage(channelFactory, subscription, false);
                                }
                                access(clientId);
                        }
                        }
                }
                catch (Exception e) {
                        log.error(e, "Could not recreate channel/subscriptions from distributed data: %s", clientId);
                }
        }

        return (timeChannel != null ? timeChannel.getChannel() : null);
    }

    public Channel removeChannel(String channelId, boolean timeout) {
        if (channelId == null)
            return null;

        // Remove existing channel id/subscriptions in distributed data (clustering).
        try {
                DistributedData gdd = graniteConfig.getDistributedDataFactory().getInstance();
                if (gdd != null) {
                        log.debug("Removing channel id from distributed data: %s", channelId);
                        gdd.removeChannelId(channelId);
                }
                }
                catch (Exception e) {
                        log.error(e, "Could not remove channel id from distributed data: %s", channelId);
                }
        
        TimeChannel<?> timeChannel = channels.get(channelId);
        Channel channel = null;
        if (timeChannel != null) {
                try {
                        if (timeChannel.getTimerTask() != null)
                                timeChannel.getTimerTask().cancel();
                }
                catch (Exception e) {
                        // Should never happen...
                }
                
                channel = timeChannel.getChannel();
                
                try {
                    for (Subscription subscription : channel.getSubscriptions()) {
                        try {
                                Message message = subscription.getUnsubscribeMessage();
                                handleMessage(channel.getFactory(), message, true);
                        }
                        catch (Exception e) {
                                log.error(e, "Error while unsubscribing channel: %s from subscription: %s", channel, subscription);
                        }
                    }
                }
                finally {
                        channels.remove(channelId);
                        channel.destroy(timeout);
                }
        }
        return channel;
    }
    
    public boolean access(String channelId) {
        if (channelId != null) {
                TimeChannel<?> timeChannel = channels.get(channelId);
                if (timeChannel != null) {
                        synchronized (timeChannel) {
                                TimerTask timerTask = timeChannel.getTimerTask();
                                if (timerTask != null) {
                                    log.debug("Canceling TimerTask: %s", timerTask);
                                    timerTask.cancel();
                                        timeChannel.setTimerTask(null);
                                }
                            
                                timerTask = new ChannelTimerTask(this, channelId);
                            timeChannel.setTimerTask(timerTask);
                            
                            long timeout = gravityConfig.getChannelIdleTimeoutMillis();
                            log.debug("Scheduling TimerTask: %s for %s ms.", timerTask, timeout);
                            channelsTimer.schedule(timerTask, timeout);
                            return true;
                        }
                }
        }
        return false;
    }
    
    public void execute(AsyncChannelRunner runner) {
        if (gravityPool == null) {
                runner.reset();
                throw new NullPointerException("Gravity not started or pool disabled");
        }
        gravityPool.execute(runner);
    }
    
    public boolean cancel(AsyncChannelRunner runner) {
        if (gravityPool == null) {
                runner.reset();
                throw new NullPointerException("Gravity not started or pool disabled");
        }
        return gravityPool.remove(runner);
    }

    ///////////////////////////////////////////////////////////////////////////
    // Incoming message handling.

    public Message handleMessage(final ChannelFactory<?> channelFactory, Message message) {
        return handleMessage(channelFactory, message, false);
    }

    public Message handleMessage(final ChannelFactory<?> channelFactory, final Message message, boolean skipInterceptor) {

        AMF3MessageInterceptor interceptor = null;
        if (!skipInterceptor)
                interceptor = GraniteContext.getCurrentInstance().getGraniteConfig().getAmf3MessageInterceptor();
        
        Message reply = null;
        boolean publish = false;
        
        try {
                if (interceptor != null)
                    interceptor.before(message);

                if (message instanceof CommandMessage) {
                    CommandMessage command = (CommandMessage)message;
        
                    switch (command.getOperation()) {
        
                    case CommandMessage.LOGIN_OPERATION:
                    case CommandMessage.LOGOUT_OPERATION:
                        return handleSecurityMessage(command);
        
                    case CommandMessage.CLIENT_PING_OPERATION:
                        return handlePingMessage(channelFactory, command);
                    case CommandMessage.CONNECT_OPERATION:
                        return handleConnectMessage(channelFactory, command);
                    case CommandMessage.DISCONNECT_OPERATION:
                        return handleDisconnectMessage(channelFactory, command);
                    case CommandMessage.SUBSCRIBE_OPERATION:
                        return handleSubscribeMessage(channelFactory, command);
                    case CommandMessage.UNSUBSCRIBE_OPERATION:
                        return handleUnsubscribeMessage(channelFactory, command);
        
                    default:
                        throw new UnsupportedOperationException("Unsupported command operation: " + command);
                    }
                }
        
                reply = handlePublishMessage(channelFactory, (AsyncMessage)message);
                publish = true;
        }
        finally {
                if (interceptor != null)
                    interceptor.after(message, reply);
        }
        
        if (reply != null) {
                GraniteContext context = GraniteContext.getCurrentInstance();
                if (context.getSessionId() != null) {
                        reply.setHeader("org.granite.sessionId", context.getSessionId());
                    if (publish && context instanceof ServletGraniteContext && ((ServletGraniteContext)context).getSession(false) != null) {
                        long serverTime = new Date().getTime();
                        ((ServletGraniteContext)context).getSession().setAttribute(GraniteContext.SESSION_LAST_ACCESSED_TIME_KEY, serverTime);
                        reply.setHeader("org.granite.time", serverTime);
                        reply.setHeader("org.granite.sessionExp", ((ServletGraniteContext)context).getSession().getMaxInactiveInterval());
                    }
                }
        }
        
        return reply;
    }

    ///////////////////////////////////////////////////////////////////////////
    // Other Public API methods.

    public GraniteContext initThread(String sessionId, String clientType) {
        GraniteContext context = GraniteContext.getCurrentInstance();
        if (context == null)
            context = SimpleGraniteContext.createThreadInstance(graniteConfig, servicesConfig, sessionId, applicationMap, clientType);
        return context;
    }
    
    public void releaseThread() {
        GraniteContext.release();
        }

        public Message publishMessage(AsyncMessage message) {
        return publishMessage(serverChannel, message);
    }

    public Message publishMessage(Channel fromChannel, AsyncMessage message) {
        initThread(null, fromChannel != null ? fromChannel.getClientType() : serverChannel.getClientType());

        return handlePublishMessage(null, message, fromChannel != null ? fromChannel : serverChannel);
    }

    private Message handlePingMessage(ChannelFactory<?> channelFactory, CommandMessage message) {
        
        Channel channel = createChannel(channelFactory, (String)message.getClientId());
        
        AsyncMessage reply = new AcknowledgeMessage(message);
        reply.setClientId(channel.getId());
        Map<String, Object> advice = new HashMap<String, Object>();
        advice.put(RECONNECT_INTERVAL_MS_KEY, Long.valueOf(gravityConfig.getReconnectIntervalMillis()));
        advice.put(RECONNECT_MAX_ATTEMPTS_KEY, Long.valueOf(gravityConfig.getReconnectMaxAttempts()));
        advice.put(ENCODE_MESSAGE_BODY_KEY, Boolean.valueOf(gravityConfig.isEncodeMessageBody()));
        reply.setBody(advice);
        reply.setDestination(message.getDestination());

        log.debug("handshake.handle: reply=%s", reply);

        return reply;
    }

    private Message handleSecurityMessage(CommandMessage message) {
        GraniteConfig config = GraniteContext.getCurrentInstance().getGraniteConfig();

        Message response = null;

        if (!config.hasSecurityService())
            log.warn("Ignored security operation (no security settings in granite-config.xml): %s", message);
        else if (!config.getSecurityService().acceptsContext())
            log.info("Ignored security operation (security service does not handle this kind of granite context)", message);
        else {
            SecurityService securityService = config.getSecurityService();
            try {
                if (message.isLoginOperation())
                    securityService.login(message.getBody(), (String)message.getHeader(Message.CREDENTIALS_CHARSET_HEADER));
                else
                    securityService.logout();
            }
            catch (Exception e) {
                if (e instanceof SecurityServiceException)
                    log.debug(e, "Could not process security operation: %s", message);
                else
                    log.error(e, "Could not process security operation: %s", message);
                response = new ErrorMessage(message, e, true);
            }
        }

        if (response == null) {
            response = new AcknowledgeMessage(message, true);
            // For SDK 2.0.1_Hotfix2.
            if (message.isSecurityOperation())
                response.setBody("success");
        }

        return response;
    }

    private Message handleConnectMessage(final ChannelFactory<?> channelFactory, CommandMessage message) {
        Channel client = getChannel(channelFactory, (String)message.getClientId());

        if (client == null)
            return handleUnknownClientMessage(message);

        return null;
    }

    private Message handleDisconnectMessage(final ChannelFactory<?> channelFactory, CommandMessage message) {
        Channel client = getChannel(channelFactory, (String)message.getClientId());
        if (client == null)
            return handleUnknownClientMessage(message);

        removeChannel(client.getId(), false);

        AcknowledgeMessage reply = new AcknowledgeMessage(message);
        reply.setDestination(message.getDestination());
        reply.setClientId(client.getId());
        return reply;
    }

    private Message handleSubscribeMessage(final ChannelFactory<?> channelFactory, final CommandMessage message) {
        return handleSubscribeMessage(channelFactory, message, true);
    }
    
    private Message handleSubscribeMessage(final ChannelFactory<?> channelFactory, final CommandMessage message, final boolean saveMessageInSession) {

        final GraniteContext context = GraniteContext.getCurrentInstance();

        // Get and check destination.
        final Destination destination = context.getServicesConfig().findDestinationById(
            message.getMessageRefType(),
            message.getDestination()
        );

        if (destination == null)
            return getInvalidDestinationError(message);


        GravityInvocationContext invocationContext = new GravityInvocationContext(message, destination) {
                        @Override
                        public Object invoke() throws Exception {
                        // Subscribe...
                        Channel channel = getChannel(channelFactory, (String)message.getClientId());
                        if (channel == null)
                            return handleUnknownClientMessage(message);

                        String subscriptionId = (String)message.getHeader(AsyncMessage.DESTINATION_CLIENT_ID_HEADER);
                        if (subscriptionId == null) {
                            subscriptionId = UUIDUtil.randomUUID();
                            message.setHeader(AsyncMessage.DESTINATION_CLIENT_ID_HEADER, subscriptionId);
                        }
                        
                        DistributedData gdd = graniteConfig.getDistributedDataFactory().getInstance();
                        if (gdd != null) {
                            if (!gdd.hasChannelId(channel.getId()))
                                gdd.addChannelId(channel.getId(), channel.getFactory().getClass().getName(), context.getClientType());
                            
                                if (Boolean.TRUE.toString().equals(destination.getProperties().get("session-selector"))) {
                                        String selector = gdd.getDestinationSelector(destination.getId());
                                        log.debug("Session selector found: %s", selector);
                                        if (selector != null)
                                                message.setHeader(CommandMessage.SELECTOR_HEADER, selector);
                                }
                        }

                        ServiceAdapter adapter = adapterFactory.getServiceAdapter(message);
                        
                        AsyncMessage reply = (AsyncMessage)adapter.manage(channel, message);
                        
                        postManage(channel);
                        
                        if (saveMessageInSession && !(reply instanceof ErrorMessage)) {
                                // Save subscription message in distributed data (clustering).
                                try {
                                        if (gdd != null) {
                                                log.debug("Saving new subscription message for channel: %s - %s", channel.getId(), message);
                                                gdd.addSubcription(channel.getId(), message);
                                        }
                                }
                                catch (Exception e) {
                                        log.error(e, "Could not add subscription in distributed data: %s - %s", channel.getId(), subscriptionId);
                                }
                        }

                        reply.setDestination(message.getDestination());
                        reply.setClientId(channel.getId());
                        reply.getHeaders().putAll(message.getHeaders());

                        if (gdd != null && message.getDestination() != null) {
                                gdd.setDestinationClientId(message.getDestination(), channel.getId());
                                gdd.setDestinationSubscriptionId(message.getDestination(), subscriptionId);
                        }

                        return reply;
                        }               
        };

        // Check security 1 (destination).
        if (destination.getSecurizer() instanceof GravityDestinationSecurizer) {
            try {
                ((GravityDestinationSecurizer)destination.getSecurizer()).canSubscribe(invocationContext);
            } 
            catch (Exception e) {
                return new ErrorMessage(message, e);
            }
        }
        
        // Check security 2 (security service).
        GraniteConfig config = context.getGraniteConfig();
        try {
            if (config.hasSecurityService() && config.getSecurityService().acceptsContext())
                return (Message)config.getSecurityService().authorize(invocationContext);
                
            return (Message)invocationContext.invoke();
        }
        catch (Exception e) {
            return new ErrorMessage(message, e, true);
        }
    }

    private Message handleUnsubscribeMessage(final ChannelFactory<?> channelFactory, CommandMessage message) {
        Channel channel = getChannel(channelFactory, (String)message.getClientId());
        if (channel == null)
            return handleUnknownClientMessage(message);

        AsyncMessage reply = null;

        ServiceAdapter adapter = adapterFactory.getServiceAdapter(message);
        
        reply = (AcknowledgeMessage)adapter.manage(channel, message);
        
        postManage(channel);
        
        if (!(reply instanceof ErrorMessage)) {
                // Remove subscription message in distributed data (clustering).
                try {
                        DistributedData gdd = graniteConfig.getDistributedDataFactory().getInstance();
                        if (gdd != null) {
                                String subscriptionId = (String)message.getHeader(AsyncMessage.DESTINATION_CLIENT_ID_HEADER);
                                log.debug("Removing subscription message from channel info: %s - %s", channel.getId(), subscriptionId);
                                gdd.removeSubcription(channel.getId(), subscriptionId);
                        }
                }
                catch (Exception e) {
                        log.error(
                                e, "Could not remove subscription from distributed data: %s - %s",
                                channel.getId(), message.getHeader(AsyncMessage.DESTINATION_CLIENT_ID_HEADER)
                        );
                }
        }

        reply.setDestination(message.getDestination());
        reply.setClientId(channel.getId());
        reply.getHeaders().putAll(message.getHeaders());

        return reply;
    }
    
    protected void postManage(Channel channel) {
    }

    private Message handlePublishMessage(final ChannelFactory<?> channelFactory, final AsyncMessage message) {
        return handlePublishMessage(channelFactory, message, null);
    }
    
    private Message handlePublishMessage(final ChannelFactory<?> channelFactory, final AsyncMessage message, final Channel channel) {

        GraniteContext context = GraniteContext.getCurrentInstance();

        // Get and check destination.
        Destination destination = context.getServicesConfig().findDestinationById(
            message.getClass().getName(),
            message.getDestination()
        );

        if (destination == null)
            return getInvalidDestinationError(message);
                
        if (message.getMessageId() == null)
                message.setMessageId(UUIDUtil.randomUUID());
        message.setTimestamp(System.currentTimeMillis());
        if (channel != null)
                message.setClientId(channel.getId());

        GravityInvocationContext invocationContext = new GravityInvocationContext(message, destination) {
                        @Override
                        public Object invoke() throws Exception {
                        // Publish...
                        Channel fromChannel = channel;
                        if (fromChannel == null)
                                fromChannel = getChannel(channelFactory, (String)message.getClientId());
                        if (fromChannel == null)
                            return handleUnknownClientMessage(message);

                        ServiceAdapter adapter = adapterFactory.getServiceAdapter(message);
                        
                        AsyncMessage reply = (AsyncMessage)adapter.invoke(fromChannel, message);

                        reply.setDestination(message.getDestination());
                        reply.setClientId(fromChannel.getId());

                        return reply;
                        }               
        };

        // Check security 1 (destination).
        if (destination.getSecurizer() instanceof GravityDestinationSecurizer) {
            try {
                ((GravityDestinationSecurizer)destination.getSecurizer()).canPublish(invocationContext);
            } 
            catch (Exception e) {
                return new ErrorMessage(message, e, true);
            }
        }
        
        // Check security 2 (security service).
        GraniteConfig config = context.getGraniteConfig();
        try {
                if (config.hasSecurityService() && config.getSecurityService().acceptsContext())
                return (Message)config.getSecurityService().authorize(invocationContext);

                return (Message)invocationContext.invoke();
        } 
        catch (Exception e) {
            return new ErrorMessage(message, e, true);
        }
    }

    private Message handleUnknownClientMessage(Message message) {
        ErrorMessage reply = new ErrorMessage(message, true);
        reply.setFaultCode("Server.Call.UnknownClient");
        reply.setFaultString("Unknown client");
        return reply;
    }

    ///////////////////////////////////////////////////////////////////////////
    // Utilities.

    private ErrorMessage getInvalidDestinationError(Message message) {

        String messageType = message.getClass().getName();
        if (message instanceof CommandMessage)
            messageType += '[' + ((CommandMessage)message).getMessageRefType() + ']';

        ErrorMessage reply = new ErrorMessage(message, true);
        reply.setFaultCode("Server.Messaging.InvalidDestination");
        reply.setFaultString(
            "No configured destination for id: " + message.getDestination() +
            " and message type: " + messageType
        );
        return reply;
    }

    private static class ServerChannel extends AbstractChannel implements Serializable {

                private static final long serialVersionUID = 1L;
                
                public ServerChannel(Gravity gravity, String channelId, ChannelFactory<ServerChannel> factory, String clientType) {
                super(gravity, channelId, factory, clientType);
        }

                @Override
                public Gravity getGravity() {
                        return gravity;
                }
                
                public void close() {
                }               

                @Override
                public void receive(AsyncMessage message) throws MessageReceivingException {
                }

                @Override
                protected boolean hasAsyncHttpContext() {
                        return false;
                }

                @Override
                protected AsyncHttpContext acquireAsyncHttpContext() {
                        return null;
                }

                @Override
                protected void releaseAsyncHttpContext(AsyncHttpContext context) {
                }
    }
}