/*
* Copyright 2005 Joe Walker
*
* 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.directwebremoting.export;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.directwebremoting.Hub;
import org.directwebremoting.HubFactory;
import org.directwebremoting.ScriptBuffer;
import org.directwebremoting.ScriptSession;
import org.directwebremoting.WebContext;
import org.directwebremoting.WebContextFactory;
import org.directwebremoting.event.DefaultMessageEvent;
import org.directwebremoting.event.MessageEvent;
import org.directwebremoting.event.MessageListener;
import org.directwebremoting.extend.ConverterManager;
import org.directwebremoting.extend.IdGenerator;
import org.directwebremoting.extend.RealRawData;
import org.directwebremoting.impl.DefaultCallbackHelper;
/**
* Various functions exported by DWR to help us with various book-keeping
* duties.
* @author Joe Walker [joe at getahead dot ltd dot uk]
*/
public class System
{
/**
* Generates and returns a new unique id suitable to use for the
* CSRF session cookie. This method is itself exempted from CSRF checking.
*/
public String generateId()
{
WebContext webContext = WebContextFactory.get();
IdGenerator idGenerator = webContext.getContainer().getBean(IdGenerator.class);
return idGenerator.generate();
}
/**
* A method designed to be called on page load so the client knows about
* the http and script sessions. This method doesn't actually do anything
* however it does allow DWR's script session checking code to work
*/
public void pageLoaded()
{
}
/**
* A method designed to be called when the client is offline.
* When the server is back online this method will return immediately
* so reverse AJAX polling may resume.
*/
public void checkHeartbeat()
{
}
/**
* Call {@link ScriptSession#invalidate()} on the {@link ScriptSession}
* that called this method.
* Used by the page unloader.
*/
public void pageUnloaded()
{
WebContext wctx = WebContextFactory.get();
ScriptSession scriptSession = wctx.getScriptSession();
log.debug("pageUnloaded is invalidating scriptSession: " + scriptSession);
scriptSession.invalidate();
}
/**
* Used by reverse ajax proxies to send data back to the server
* @param key The unique id under which a callback is registered
* @param data The data to decode and pass to the callback
*/
public void activateCallback(String key, RealRawData data)
{
try
{
DefaultCallbackHelper.executeCallback(key, data);
}
catch (Exception ex)
{
log.error("Failed to marshall data from callback", ex);
}
}
/**
* Something has published to the client side 'hub' and we're getting to
* know about it.
* @param topic The topic that has been published to
* @param data The published data
*/
public void publish(String topic, RealRawData data)
{
WebContext webContext = WebContextFactory.get();
ConverterManager converterManager = webContext.getContainer().getBean(ConverterManager.class);
Hub hub = HubFactory.get();
MessageEvent event = new DefaultMessageEvent(hub, converterManager, data);
hub.publish(topic, event);
}
/**
* Ensure that the clients know about server publishes
* @param topic The topic being subscribed to
* @param subscriptionId The ID to pass back to link to client side data
*/
@SuppressWarnings("unchecked")
public void subscribe(String topic, String subscriptionId)
{
WebContext webContext = WebContextFactory.get();
Hub hub = HubFactory.get();
final ScriptSession session = webContext.getScriptSession();
// Create a subscription block
BrowserMessageListener subscription = new BrowserMessageListener(session, topic, subscriptionId);
Map<String, BrowserMessageListener> subscriptions = (Map<String, BrowserMessageListener>) session.getAttribute(ATTRIBUTE_SUBSCRIPTIONS);
if (subscriptions == null)
{
subscriptions = new HashMap<String, BrowserMessageListener>();
}
subscriptions.put(subscriptionId, subscription);
session.setAttribute(ATTRIBUTE_SUBSCRIPTIONS, subscriptions);
hub.subscribe(subscription.topic, subscription);
}
/**
* Stop notifications of against a subscription id
* @param subscriptionId The ID to pass back to link to client side data
* @return true iff someone was unsubscribed
*/
@SuppressWarnings("unchecked")
public boolean unsubscribe(String subscriptionId)
{
WebContext webContext = WebContextFactory.get();
Hub hub = HubFactory.get();
ScriptSession session = webContext.getScriptSession();
Map<String, BrowserMessageListener> subscriptions = (Map<String, BrowserMessageListener>) session.getAttribute(ATTRIBUTE_SUBSCRIPTIONS);
BrowserMessageListener subscription = subscriptions.get(subscriptionId);
return hub.unsubscribe(subscription.topic, subscription);
}
/**
* A struct to collect the data we need to remember against a subscription
*/
protected class BrowserMessageListener implements MessageListener
{
/**
*
*/
public BrowserMessageListener(ScriptSession session, String topic, String subscriptionId)
{
this.session = session;
this.topic = topic;
this.subscriptionId = subscriptionId;
}
/* (non-Javadoc)
* @see org.directwebremoting.event.MessageListener#onMessage(org.directwebremoting.event.MessageEvent)
*/
public void onMessage(MessageEvent message)
{
ScriptBuffer script = new ScriptBuffer();
script.appendCall("dwr.hub._remotePublish", subscriptionId, message.getRawData());
session.addScript(script);
}
protected String topic;
protected String subscriptionId;
protected ScriptSession session;
}
/**
*
*/
private static final String ATTRIBUTE_SUBSCRIPTIONS = "org.directwebremoting.export.System.subscriptions";
/**
* The log stream
*/
private static final Log log = LogFactory.getLog(System.class);
}