org.cometd.oort.OortComet Maven / Gradle / Ivy
/*
* Copyright (c) 2010 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.cometd.oort;
import java.util.Arrays;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.cometd.bayeux.Channel;
import org.cometd.bayeux.Message;
import org.cometd.bayeux.client.ClientSessionChannel;
import org.cometd.client.BayeuxClient;
import org.cometd.client.transport.LongPollingTransport;
/**
* The Oort comet client connects a local Oort comet server to a remote Oort comet server.
*
*/
public class OortComet extends BayeuxClient
{
private final ConcurrentMap _subscriptions = new ConcurrentHashMap();
private final Oort _oort;
private final String _cometURL;
private volatile boolean _subscriptionsAllowed;
public OortComet(Oort oort, String cometUrl)
{
super(cometUrl, LongPollingTransport.create(null, oort.getHttpClient()));
_oort = oort;
_cometURL = cometUrl;
setDebugEnabled(oort.isClientDebugEnabled());
// Add listener for handshake response
getChannel(Channel.META_HANDSHAKE).addListener(new ClientSessionChannel.MessageListener()
{
public void onMessage(ClientSessionChannel channel, Message message)
{
if (message.isSuccessful())
{
batch(new Runnable()
{
public void run()
{
// Subscribe to cloud notifications
getChannel(Oort.OORT_CLOUD_CHANNEL).subscribe(new ClientSessionChannel.MessageListener()
{
public void onMessage(ClientSessionChannel channel, Message message)
{
if (message.isSuccessful())
_oort.joinComets(_cometURL, message);
}
});
// It is possible that a call to Oort.observeChannel() (which triggers
// the call to subscribe()) is performed concurrently with the handshake
// of this OortComet with a remote comet.
// For example, Seti calls Oort.observeChannel() on startup and this may
// be called while the Oort cloud is connecting all the comets together.
// In this case, below we will clear existing subscriptions, but we will
// subscribe them again just afterwards, ensuring only one subscriber
// (and not multiple ones) is subscribed.
clearSubscriptions();
_subscriptionsAllowed = true;
subscribe(_oort.getObservedChannels());
getChannel(Oort.OORT_CLOUD_CHANNEL).publish(_oort.getKnownComets().toArray());
}
});
_oort.getLogger().info("Connected to comet {} with {}", _cometURL, message.getClientId());
}
else
{
_oort.getLogger().warn("Failed to connect to comet {}, message {}", _cometURL, message);
}
}
});
}
protected void subscribe(Set observedChannels)
{
// Guard against concurrent subscription clearing from the handshake callback
if (!_subscriptionsAllowed)
return;
for (String channel : observedChannels)
{
if (_subscriptions.containsKey(channel))
continue;
ClientSessionChannel.MessageListener listener = new ClientSessionChannel.MessageListener()
{
public void onMessage(ClientSessionChannel channel, Message message)
{
_oort.getLogger().debug("Republishing message {} from {}", message, _cometURL);
// BayeuxServer may sweep channels, so calling bayeux.getChannel(...)
// may return null, and therefore we use the client to send the message
_oort.getOortSession().getChannel(message.getChannel()).publish(message.getData(), message.getId());
}
};
ClientSessionChannel.MessageListener existing = _subscriptions.putIfAbsent(channel, listener);
if (existing == null)
{
_oort.getLogger().debug("Subscribing to messages on {} from {}", channel, _cometURL);
getChannel(channel).subscribe(listener);
}
}
_oort.getLogger().debug("Subscriptions to messages on {} from {}", _subscriptions, _cometURL);
}
protected void unsubscribe(String channel)
{
ClientSessionChannel.MessageListener listener = _subscriptions.remove(channel);
if (listener != null)
{
_oort.getLogger().debug("Unsubscribing to messages on {} from {}", channel, _cometURL);
getChannel(channel).unsubscribe(listener);
}
}
protected void clearSubscriptions()
{
for (String channel : _oort.getObservedChannels())
unsubscribe(channel);
}
@Override
public void onFailure(Throwable x, Message[] messages)
{
_oort.getLogger().debug("Failure, messages: " + Arrays.asList(messages), x);
}
@Override
public String toString()
{
return _cometURL + "@" + getId();
}
}