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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 flex.messaging;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import flex.management.ManageableComponent;
import flex.management.runtime.messaging.services.ServiceControl;
import flex.messaging.log.LogCategories;
import flex.messaging.log.Log;
import flex.messaging.services.Service;
import flex.messaging.services.ServiceAdapter;
import flex.messaging.util.ClassUtil;
import flex.messaging.cluster.ClusterManager;
import flex.messaging.config.ClusterSettings;
import flex.messaging.config.ConfigMap;
import flex.messaging.config.ConfigurationConstants;
import flex.messaging.config.ConfigurationException;
import flex.messaging.config.NetworkSettings;
import flex.messaging.config.SecurityConstraint;
/**
 * The Destination class is a source and sink for messages sent through
 * a service destination and uses an adapter to process messages.
 */
public class Destination extends ManageableComponent implements java.io.Serializable
{
    static final long serialVersionUID = -977001797620881435L;

    /** Default log category for Destination. */
    public static final String LOG_CATEGORY = LogCategories.SERVICE_GENERAL;
    
    /** Hard coded id for the push destination */
    public static final String PUSH_DESTINATION_ID = "_DS_PUSH_";

    // Errors
    private static final int NO_SERVICE = 11117;

    // Destination's properties
    protected ServiceAdapter adapter;
    protected List channelIds;
    protected NetworkSettings networkSettings;
    protected SecurityConstraint securityConstraint;
    protected String securityConstraintRef;
    protected HashMap extraProperties;
    protected boolean initialized;
    protected boolean clustered;
    protected boolean clusteredCalculated;

    //--------------------------------------------------------------------------
    //
    // Constructor
    //
    //--------------------------------------------------------------------------

    /**
     * Constructs an unmanaged Destination instance.
     */
    public Destination()
    {
        this(false);
    }

    /**
     * Constructs a Destination with the indicated management.
     *
     * @param enableManagement true if the Destination
     * is manageable; otherwise false.
     */
    public Destination(boolean enableManagement)
    {
        super(enableManagement);

        networkSettings = new NetworkSettings();
    }

    //--------------------------------------------------------------------------
    //
    // Initialize, validate, start, and stop methods.
    //
    //--------------------------------------------------------------------------

    /**
     * Initializes the Destination with the properties.
     * If subclasses override, they must call super.initialize().
     *
     * @param id The id of the destination.
     * @param properties Properties for the destination.
     */
    @Override
    public void initialize(String id, ConfigMap properties)
    {
        super.initialize(id, properties);

        if (properties == null || properties.size() == 0)
        {
            initialized = true;
            return;
        }

        ConfigMap network = properties.getPropertyAsMap(NetworkSettings.NETWORK_ELEMENT, null);

        if (network != null)
        {
            networkSettings.setReliable(network.getPropertyAsBoolean(NetworkSettings.RELIABLE_ELEMENT, false));

            ConfigMap clusterInfo = network.getPropertyAsMap(ClusterSettings.CLUSTER_ELEMENT, null);
            if (clusterInfo != null)
            {
                // Mark these as used so we do not get warnings about them.
                network.allowProperty(ClusterSettings.CLUSTER_ELEMENT);
                clusterInfo.allowProperty(ClusterSettings.REF_ATTR);
                clusterInfo.allowProperty(ClusterSettings.SHARED_BACKEND_ATTR);

                String clusterId = clusterInfo.getPropertyAsString(ClusterSettings.REF_ATTR, null);
                String coordinatorPolicy = clusterInfo.getPropertyAsString(ClusterSettings.SHARED_BACKEND_ATTR, null);
                if (coordinatorPolicy != null)
                    networkSettings.setSharedBackend(Boolean.valueOf(coordinatorPolicy));

                networkSettings.setClusterId(clusterId);
            }
        }

        initialized = true;
    }

    /**
     *  Returns whether or not the destination has been initialized.
     *
     * @return True, if the destination has been initialized.
     */
    public boolean isInitialized()
    {
        return initialized;
    }

    /**
     * Verifies that the Destination is in valid state before
     * it is started. If subclasses override, they must call super.validate().
     */
    @Override
    protected void validate()
    {
        if (isValid())
            return;

        super.validate();

        if (getAdapter() == null)
        {
            String defaultAdapterId = getService().getDefaultAdapter();
            if (defaultAdapterId != null)
            {
                createAdapter(defaultAdapterId);
            }
            else
            {
                invalidate();
                // Destination '{id}' must specify at least one adapter.
                ConfigurationException ex = new ConfigurationException();
                ex.setMessage(ConfigurationConstants.DEST_NEEDS_ADAPTER, new Object[]{getId()});
                throw ex;
            }
        }

        if (channelIds != null)
        {
            List brokerChannelIds = getService().getMessageBroker().getChannelIds();
            for (Iterator iter = channelIds.iterator(); iter.hasNext();)
            {
                String id = iter.next();
                if (brokerChannelIds == null || !brokerChannelIds.contains(id))
                {
                    iter.remove();
                    if (Log.isWarn())
                    {
                        Log.getLogger(getLogCategory()).warn("No channel with id '{0}' is known by the MessageBroker." +
                                " Removing the channel.",
                                new Object[]{id});
                    }
                }
            }
        }

        // Set the default channels if needed
        if (channelIds == null)
        {
            List defaultChannelIds = getService().getDefaultChannels();
            if (defaultChannelIds != null && defaultChannelIds.size() > 0)
            {
                setChannels(defaultChannelIds);
            }
            else
            {
                invalidate();
                // Destination '{id}' must specify at least one channel.
                ConfigurationException ex = new ConfigurationException();
                ex.setMessage(ConfigurationConstants.DEST_NEEDS_CHANNEL, new Object[]{getId()});
                throw ex;
            }
        }

        MessageBroker broker = getService().getMessageBroker();

        // Validate the security constraint
        if (securityConstraint == null && securityConstraintRef != null)
        {
            securityConstraint = broker.getSecurityConstraint(securityConstraintRef);
            // No need to throw an error as MessageBroker automatically throws
            // an error if no such constraint exists
        }

        ClusterManager cm = broker.getClusterManager();

        // Set clustering if needed
        if (getNetworkSettings().getClusterId() != null || cm.getDefaultClusterId() != null)
        {
            cm.clusterDestination(this);
        }
    }

    /**
     * Starts the destination if its associated Service is started
     * and if the destination is not already running. The default implementation
     * of this method starts the adapter of the destination. If subclasses
     * override, they must call super.start().
     */
    @Override
    public void start()
    {
        if (isStarted())
        {
            // Needed for adapters added after startup.
            getAdapter().start();
            return;
        }

        // Check if the Service is started
        Service service = getService();
        if (!service.isStarted())
        {
            if (Log.isWarn())
            {
                Log.getLogger(getLogCategory()).warn("Destination with id '{0}' cannot be started" +
                        " when its Service with id '{1}' is not started.",
                        new Object[]{getId(), service.getId()});
            }
            return;
        }

        // Set up management
        if (isManaged() && service.isManaged())
        {
            setupDestinationControl(service);
            ServiceControl controller = (ServiceControl)service.getControl();
            if (getControl() != null)
                controller.addDestination(getControl().getObjectName());
        }

        super.start();

        getAdapter().start();
    }

    /**
     * The default implementation of this method stops all of the adapters
     * of the destination.
     * If subclasses override, they must call super.stop().
     *
     */
    @Override
    public void stop()
    {
        if (!isStarted())
            return;

        getAdapter().stop();

        super.stop();

        // Remove management
        if (isManaged() && getService().isManaged())
        {
            if (getControl() != null)
            {
                getControl().unregister();
                setControl(null);
            }
            setManaged(false);
        }

    }

    //--------------------------------------------------------------------------
    //
    // Public Getters and Setters for Destination properties
    //
    //--------------------------------------------------------------------------

    /**
     * Returns the ServiceAdapter for the Destination.
     *
     * @return The ServiceAdapter for the Destination.
     */
    public ServiceAdapter getAdapter()
    {
        return adapter;
    }

    /**
     * Creates a ServiceAdapter instance, sets its id, sets it manageable
     * if the Destination that created it is manageable,
     * and set its Destination to the Destination that
     * created it.
     *
     * In order to use this method, Destination should have an assigned
     * Service and the id provided for the adapter should already
     * be registered with the Service.
     *
     * @param id The id of the ServiceAdapter.
     * @return The ServiceAdapter instanced created.
     */
    public ServiceAdapter createAdapter(String id)
    {
        if (getService() == null)
        {
            // Destination cannot create adapter '{0}' without its Service set.
            ConfigurationException ex = new ConfigurationException();
            ex.setMessage(NO_SERVICE, new Object[]{id});
            throw ex;
        }
        Map adapterClasses = getService().getRegisteredAdapters();
        if (!adapterClasses.containsKey(id))
        {
            // No adapter with id '{0}' is registered with the service '{1}'.
            ConfigurationException ex = new ConfigurationException();
            ex.setMessage(ConfigurationConstants.UNREGISTERED_ADAPTER, new Object[]{id, getService().getId()});
            throw ex;
        }

        String adapterClassName = adapterClasses.get(id);
        Class adapterClass = ClassUtil.createClass(adapterClassName,
                FlexContext.getMessageBroker() == null ?
                      null : FlexContext.getMessageBroker().getClassLoader());

        ServiceAdapter adapter = (ServiceAdapter)ClassUtil.createDefaultInstance(adapterClass, ServiceAdapter.class);
        adapter.setId(id);
        adapter.setManaged(isManaged());
        adapter.setDestination(this);

        return adapter;
    }

    /**
     * Sets the ServiceAdapter of the Destination.
     *
     * ServiceAdapter needs to be started if the Destination
     * is already running.
     *
     * @param adapter The adapter for the destination.
     */
    public void setAdapter(ServiceAdapter adapter)
    {
        if (getAdapter() == adapter) // No need to reset the adapter.
            return;

        if (adapter == null)
        {
            removeAdapter();
            return;
        }

        addAdapter(adapter);
    }

    /**
     * Used by setAdapter and it removes the old adapter of the destination
     * and adds the new adapter.
     *
     * @param adapter The adapter for the destination.
     */
    private void addAdapter(ServiceAdapter adapter)
    {
        removeAdapter();

        this.adapter = adapter;

        if (adapter.getDestination() == null || adapter.getDestination() != this)
            adapter.setDestination(this);
    }

    /**
     * Used by setAdapter and addAdapter. It removes the current adapter
     * of the destination
     */
    private void removeAdapter()
    {
        ServiceAdapter adapter = getAdapter();
        if (adapter != null)
        {
            adapter.stop();
        }
        this.adapter = null;
    }


    /**
     * The destination may be not clustered at all, may be clustered for channel failover and
     * destination sharing, or it may be clustered for channel failover and also have a
     * common backend, such as a common database or backend clustered JMS topic.
     * If the destination is clustered and has a common backend to coordinate the cluster,
     * this method returns true; otherwise it return false. Note that this method returns
     * false if the Destination is not runnning.
     *
     * @return true if the clustered Destination shares a common backend;
     * otherwise false.
     */
    public boolean isBackendShared()
    {
        if (!isStarted())
            return false;

        ClusterManager clm = getService().getMessageBroker().getClusterManager();
        return clm.isBackendShared(getService().getClass().getName(), getId());
    }

    /**
     * Returns the list of channel ids of the Destination.
     *
     * @return The list of channel ids of the Destination.
     */
    public List getChannels()
    {
        return channelIds;
    }

    /**
     * Adds a channel to the list of channels known by the Destination.
     * MessageBroker has to know the channel. Otherwise, the channel
     * is not added to the list.
     *
     * @param id The id of the channel.
     */
    public void addChannel(String id)
    {
        if (channelIds == null)
            channelIds = new ArrayList();
        else if (channelIds.contains(id))
            return;

        if (isStarted())
        {
            List brokerChannelIds = getService().getMessageBroker().getChannelIds();
            if (brokerChannelIds == null || !brokerChannelIds.contains(id))
            {
                if (Log.isWarn())
                {
                    Log.getLogger(getLogCategory()).warn("No channel with id '{0}' is known by the MessageBroker." +
                            " Not adding the channel.",
                            new Object[]{id});
                }
                return;
            }
        }
        // Either message broker knows about the channel, or destination is not
        // running and channel will be checked before startup during validate
        channelIds.add(id);
    }

    /**
     * Removes the channel from the list of channels for the Destination.
     *
     * @param id The id of the channel.
     * @return true if the list contained the channel id.
     */
    public boolean removeChannel(String id)
    {
        return channelIds != null && channelIds.remove(id);
    }

    /**
     * Sets the channel list of the Destination.
     * MessageBroker has to know the channels, otherwise they
     * are not added to the list.
     *
     * @param ids List of channel ids.
     */
    public void setChannels(List ids)
    {
        if (ids != null && isStarted())
        {
            List brokerChannelIds = getService().getMessageBroker().getChannelIds();
            for (Iterator iter = ids.iterator(); iter.hasNext();)
            {
                String id = iter.next();
                if (brokerChannelIds == null || !brokerChannelIds.contains(id))
                {
                    iter.remove();
                    if (Log.isWarn())
                    {
                        Log.getLogger(getLogCategory()).warn("No channel with id '{0}' is known by the MessageBroker." +
                                " Not adding the channel.",
                                new Object[]{id});
                    }
                }
            }
        }
        // Otherwise, channels will be checked before startup during validate
        channelIds = ids;
    }

    /**
     * The destination may be not clustered at all, may be clustered for channel failover
     * only, or it may be clustered for channel failover and also have shared back ends.
     * If the destination is clustered, regardless of whether or not it relies on a shared
     * back end for cluster configuration, this method returns true. Note that this method
     * returns false if the Destination is not runnning.
     *
     * @return true if the Destination is clustered; otherwise false.
     */
    public boolean isClustered()
    {
        if (!isStarted())
            return false;

        if (!clusteredCalculated)
        {
            ClusterManager clm = getService().getMessageBroker().getClusterManager();
            clustered = clm.isDestinationClustered(getService().getClass().getName(), getId());
            clusteredCalculated = true;
        }
        return clustered;
    }

    /**
     * Sets the id of the Destination. If the Destination
     * has a Service assigned, it also updates the id in the
     * Service.
     *
     * @param id The id of the Destination.
     */
    @Override
    public void setId(String id)
    {
        String oldId = getId();

        super.setId(id);

        // Update the destination id in the service and MessageBroker
        Service service = getService();
        if (service != null)
        {
            service.removeDestination(oldId);
            service.addDestination(this);
        }
    }

    /**
     * Get the NetworkSettings of the Destination.
     *
     * @return The NetworkSettings of the Destination.
     */
    public NetworkSettings getNetworkSettings()
    {
        return networkSettings;
    }

    /**
     * Set the NetworkSettings of the Destination.
     *
     * @param networkSettings The NetworkSettings of the Destination.
     */
    public void setNetworkSettings(NetworkSettings networkSettings)
    {
        this.networkSettings = networkSettings;
    }

    /**
     * Returns the Service managing this Destination.
     *
     * @return The Service managing this Destination.
     */
    public Service getService()
    {
        return (Service)getParent();
    }

    /**
     * Sets the Service managing this Destination.
     * Removes the Destination from the old service
     * (if there was one) and adds to the list of destination in the new service.
     *
     * @param service The Service managing this Destination.
     */
    public void setService(Service service)
    {
        Service oldService = getService();

        setParent(service);

        if (oldService != null)
            oldService.removeDestination(getId());

        // Add the destination to the service if needed
        if (service.getDestination(getId()) != this)
            service.addDestination(this);
    }

    /**
     * Returns the Java class name for the Service managing this
     * Destination. Returns null if there is no Service
     * assigned to the Destination yet.
     *
     * @return The Java class name for the Service manageing this Destination.
     */
    public String getServiceType()
    {
        Service service = getService();
        return service != null? service.getClass().getName() : null;
    }

    /**
     * Returns the SecurityConstraint of the Destination.
     * SecurityConstraint is constructed as the Destination
     * starts up. Therefore, this could return null even if the SecurityConstraint
     * reference is set but Destination is not started yet.
     *
     * @return The SecurityConstraint of the Destination.
     */
    public SecurityConstraint getSecurityConstraint()
    {
        return securityConstraint;
    }

    /**
     * Sets the SecurityConstraint of the Destination.
     *
     * @param securityConstraint The SecurityConstraint of the Destination.
     */
    public void setSecurityConstraint(SecurityConstraint securityConstraint)
    {
        this.securityConstraint = securityConstraint;
    }

    /**
     * Sets the SecurityConstraint reference of the Destination.
     * MessageBroker has to know the SecurityConstraint
     * reference. Note that getSecurityConstraint can return null
     * if the reference is set but the Destination is not started yet.
     *
     * @param ref SecurityConstraint reference.
     */
    public void setSecurityConstraint(String ref)
    {
        if (isStarted())
        {
            MessageBroker msgBroker = getService().getMessageBroker();
            securityConstraint = msgBroker.getSecurityConstraint(ref);
            // No need to throw an error as MessageBroker automatically throws
            // an error if no such constraint exists
        }
        securityConstraintRef = ref;
    }

    //--------------------------------------------------------------------------
    //
    // Other public APIs
    //
    //--------------------------------------------------------------------------

    /**
     * Calls {@link Destination#describeDestination(boolean)} with true boolean value.
     *
     * @return A ConfigMap of destination properties that the client needs.
     * @see flex.messaging.Destination#describeDestination(boolean)
     */
    public ConfigMap describeDestination()
    {
        return describeDestination(true);
    }

    /**
     * Returns a ConfigMap of destination properties that the client
     * needs. Subclasses can add additional properties to super.describeDestination(boolean),
     * or return null if they don't want their properties to be sent to the client.
     *
     * @param onlyReliable Determines whether only reliable destination configuration should be returned.
     * @return A ConfigMap of destination properties that the client needs.
     */
    public ConfigMap describeDestination(boolean onlyReliable)
    {
        boolean reliable = networkSettings != null && networkSettings.isReliable();
        if (onlyReliable && !reliable)
            return null;

        ConfigMap destinationConfig = new ConfigMap();
        destinationConfig.addProperty(ConfigurationConstants.ID_ATTR, getId());

        // Include network settings if reliability for the destination is enabled.
        if (reliable)
        {
            ConfigMap properties = new ConfigMap();
            ConfigMap network = new ConfigMap();

            ConfigMap reliableMap = new ConfigMap();
            // Adding as a value rather than attribute to the parent
            reliableMap.addProperty(ConfigurationConstants.EMPTY_STRING, Boolean.toString(networkSettings.isReliable()));

            network.addProperty(NetworkSettings.RELIABLE_ELEMENT, reliableMap);
            properties.addProperty(NetworkSettings.NETWORK_ELEMENT, network);

            destinationConfig.addProperty(ConfigurationConstants.PROPERTIES_ELEMENT, properties);
        }

        ConfigMap channelsConfig = new ConfigMap();
        for (String id : channelIds)
        {
            ConfigMap channelConfig = new ConfigMap();
            channelConfig.addProperty(ConfigurationConstants.REF_ATTR, id);
            channelsConfig.addProperty(ConfigurationConstants.CHANNEL_ELEMENT, channelConfig);
        }

        if (channelsConfig.size() > 0)
            destinationConfig.addProperty(ConfigurationConstants.CHANNELS_ELEMENT, channelsConfig);

        return destinationConfig;
    }

    /**
     * Method for setting an extra property for the destination at runtime.
     *
     * @param name The name of the property.
     * @param value The value of the property.
     */
    public void addExtraProperty(String name, Object value)
    {
        if (extraProperties == null)
        {
            extraProperties = new HashMap();
        }

        extraProperties.put(name, value);
    }

    /**
     * Method for getting an extra property at runtime.
     *
     * @param name The name of the property.
     * @return The value of the property or null if the property does not exist.
     */
    public Object getExtraProperty(String name)
    {
        return extraProperties != null? extraProperties.get(name) : null;
    }

    //--------------------------------------------------------------------------
    //
    // Protected/private APIs
    //
    //--------------------------------------------------------------------------

    /**
     * Returns the log category of the Destination. Subclasses
     * can override to provide a more specific log category.
     *
     * @return The log category.
     */
    @Override
    protected String getLogCategory()
    {
        return LOG_CATEGORY;
    }

    /**
     * Invoked automatically to allow the Destination to setup its corresponding
     * MBean control. Subclasses should override to setup and register their MBean control.
     *
     * @param service The Service that manages this Destination.
     */
    protected void setupDestinationControl(Service service)
    {
        // Manageable subclasses should override this template method.
        setManaged(false);
    }
}




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