/*
* JBoss, Home of Professional Open Source
* Copyright 2013, Red Hat, Inc. and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This 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.
*
* This software 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 software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.richfaces.application.push;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import javax.el.ELContext;
import javax.faces.context.FacesContext;
import org.richfaces.application.ServiceTracker;
import org.richfaces.el.util.ELUtils;
/**
* <p>
* TopicsContext is a per-application singleton tracking all registered topics.
*
* <p>
* It is erroneous to communicate with the Topic not registered via TopicsContext.
* </p>
*
* <p>
* Application developer obtains instance of TopicsContext via static lookup() method.
* </p>
*
* <p>
* When TopicsContext is being looked up for the first time, it triggers creation of {@link PushContext} via
* {@link PushContextFactory} that is configured as RichFaces service.
* </p>
*
* @author Nick Belaevski
*/
public abstract class TopicsContext {
private ConcurrentMap<String, Topic> topics = new ConcurrentHashMap<String, Topic>();
/**
* Creates topic for given topic key
*/
protected abstract Topic createTopic(TopicKey key);
/**
* <p>
* Creates topic for given key or returns existing one when it was already created.
* </p>
*
* <p>
* This method is thread-safe.
* </p>
*/
public Topic getOrCreateTopic(TopicKey key) {
Topic result = topics.get(key.getTopicName());
if (result == null) {
Topic newTopic = createTopic(key);
result = topics.putIfAbsent(key.getTopicName(), newTopic);
if (result == null) {
result = newTopic;
}
}
return result;
}
/**
* Returns topic for given key or null if no such topic was created yet.
*/
public Topic getTopic(TopicKey key) {
return topics.get(key.getTopicName());
}
/**
* Removes topic with given key or does nothing when no such topic was created yet.
*/
public void removeTopic(TopicKey key) {
topics.remove(key.getTopicName());
}
/**
* <p>
* Publishes data through the topic with given key.
* </p>
*
* <p>
* The provided topic key can contain expressions as the name of topic or its subtopic. In such case, the topic name or
* subtopic name will be first evaluated, which will form actual topic key that will be used to publish a message.
* </p>
*
* @throws MessageException when topic with given key fails to publish given data object.
*/
public void publish(TopicKey key, Object data) throws MessageException {
TopicKey resolvedKey = getTopicKeyWithResolvedExpressions(key);
Topic topic = getOrCreateTopic(resolvedKey);
topic.publish(data);
}
/**
* Look-ups per-application singleton of {@link TopicsContext} tracking all registered topics.
*/
public static TopicsContext lookup() {
return ServiceTracker.getService(PushContextFactory.class).getPushContext().getTopicsContext();
}
protected TopicKey getTopicKeyWithResolvedExpressions(TopicKey key) {
String topicName = key.getTopicName();
String subtopicName = key.getSubtopicName();
String topicAddress = key.getTopicAddress();
if (isExpression(topicName) || isExpression(subtopicName)) {
topicName = evaluateExpression(topicName);
subtopicName = evaluateExpression(subtopicName);
return new TopicKey(topicName, subtopicName);
} else if (isExpression(topicAddress)) {
topicAddress = evaluateExpression(topicAddress);
return new TopicKey(topicAddress);
} else {
return key;
}
}
private boolean isExpression(String expression) {
return ELUtils.isValueReference(expression);
}
private String evaluateExpression(String expression) {
if (isExpression(expression)) {
FacesContext facesContext = FacesContext.getCurrentInstance();
ELContext elContext = facesContext.getELContext();
Object evaluated = ELUtils.evaluateValueExpression(ELUtils.createValueExpression(expression), elContext);
if (evaluated == null) {
throw new NullPointerException("expression '" + expression + "' was evaluated to null");
}
return evaluated.toString();
}
return expression;
}
}