/*
* Copyright 2009 Red Hat, Inc.
* Red Hat 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 org.hornetq.jms.example;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageProducer;
import javax.jms.Queue;
import javax.jms.QueueConnection;
import javax.jms.QueueRequestor;
import javax.jms.QueueSession;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.InitialContext;
import org.hornetq.api.jms.HornetQJMSClient;
import org.hornetq.api.jms.HornetQJMSConstants;
import org.hornetq.api.jms.management.JMSManagementHelper;
import org.hornetq.common.example.HornetQExample;
/**
*
* This example demonstrates the use of HornetQ "pre-acknowledge" functionality where
* messages are acknowledged before they are delivered to the consumer.
*
* Please see the readme.html for more details.
*
* @author <a href="mailto:tim.fox@jboss.com">Tim Fox</a>
*
*/
public class PreacknowledgeExample extends HornetQExample
{
public static void main(final String[] args)
{
new PreacknowledgeExample().run(args);
}
@Override
public boolean runExample() throws Exception
{
Connection connection = null;
InitialContext initialContext = null;
try
{
// Step 1. Create an initial context to perform the JNDI lookup.
initialContext = getContext(0);
// Step 2. Perform the look-ups
Queue queue = (Queue)initialContext.lookup("/queue/exampleQueue");
ConnectionFactory cf = (ConnectionFactory)initialContext.lookup("/ConnectionFactory");
// Step 3. Create a the JMS objects
connection = cf.createConnection();
Session session = connection.createSession(false, HornetQJMSConstants.PRE_ACKNOWLEDGE);
MessageProducer producer = session.createProducer(queue);
MessageConsumer messageConsumer = session.createConsumer(queue);
// Step 4. Create and send a message
TextMessage message1 = session.createTextMessage("This is a text message 1");
producer.send(message1);
System.out.println("Sent message: " + message1.getText());
// Step 5. Print out the message count of the queue. The queue contains one message as expected
// delivery has not yet started on the queue
int count = getMessageCount(connection);
System.out.println("Queue message count is " + count);
// Step 6. Start the Connection, delivery will now start. Give a little time for delivery to occur.
connection.start();
Thread.sleep(1000);
// Step 7. Print out the message countof the queue. It should now be zero, since the message has
// already been acknowledged even before the consumer has received it.
count = getMessageCount(connection);
System.out.println("Queue message count is now " + count);
if (count != 0)
{
return false;
}
// Step 8. Finally, receive the message
TextMessage messageReceived = (TextMessage)messageConsumer.receive(5000);
System.out.println("Received message: " + messageReceived.getText());
return true;
}
finally
{
// Step 9. Be sure to close our resources!
if (initialContext != null)
{
initialContext.close();
}
if (connection != null)
{
connection.close();
}
}
}
// To do this we send a management message to get the message count.
// In real life you wouldn't create a new session every time you send a management message
private int getMessageCount(final Connection connection) throws Exception
{
QueueSession session = ((QueueConnection)connection).createQueueSession(false, Session.AUTO_ACKNOWLEDGE);
Queue managementQueue = HornetQJMSClient.createQueue("hornetq.management");
QueueRequestor requestor = new QueueRequestor(session, managementQueue);
connection.start();
Message m = session.createMessage();
JMSManagementHelper.putAttribute(m, "jms.queue.exampleQueue", "messageCount");
Message response = requestor.request(m);
int messageCount = (Integer)JMSManagementHelper.getResult(response);
return messageCount;
}
}