/*
* 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.BytesMessage;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.DeliveryMode;
import javax.jms.MessageConsumer;
import javax.jms.MessageProducer;
import javax.jms.Queue;
import javax.jms.Session;
import javax.naming.InitialContext;
import org.hornetq.common.example.HornetQExample;
/**
* A simple JMS Queue example that creates a producer and consumer on a queue and sends then receives a message.
*
* @author <a href="csuconic@redhat.com">Clebert Suconic</a>
*/
public class PagingExample extends HornetQExample
{
public static void main(final String[] args)
{
new PagingExample().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 a lookup on the Connection Factory
ConnectionFactory cf = (ConnectionFactory)initialContext.lookup("/ConnectionFactory");
// Step 3. We look-up the JMS queue object from JNDI. pagingQueue is configured to hold a very limited number
// of bytes in memory
Queue pageQueue = (Queue)initialContext.lookup("/queue/pagingQueue");
// Step 4. Lookup for a JMS Queue
Queue queue = (Queue)initialContext.lookup("/queue/exampleQueue");
// Step 5. Create a JMS Connection
connection = cf.createConnection();
// Step 6. Create a JMS Session
Session session = connection.createSession(false, Session.CLIENT_ACKNOWLEDGE);
// Step 7. Create a JMS Message Producer for pageQueueAddress
MessageProducer pageMessageProducer = session.createProducer(pageQueue);
// Step 8. We don't need persistent messages in order to use paging. (This step is optional)
pageMessageProducer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);
// Step 9. Create a Binary Bytes Message with 10K arbitrary bytes
BytesMessage message = session.createBytesMessage();
message.writeBytes(new byte[10 * 1024]);
// Step 10. Send only 20 messages to the Queue. This will be already enough for pagingQueue. Look at
// ./paging/config/hornetq-queues.xml for the config.
for (int i = 0; i < 20; i++)
{
pageMessageProducer.send(message);
}
// Step 11. Create a JMS Message Producer
MessageProducer messageProducer = session.createProducer(queue);
// Step 12. We don't need persistent messages in order to use paging. (This step is optional)
messageProducer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);
// Step 13. Send the message for about 1K, which should be over the memory limit imposed by the server
for (int i = 0; i < 1000; i++)
{
messageProducer.send(message);
}
// Step 14. if you pause this example here, you will see several files under ./build/data/paging
// Thread.sleep(30000); // if you want to just our of curiosity, you can sleep here and inspect the created
// files just for
// Step 15. Create a JMS Message Consumer
MessageConsumer messageConsumer = session.createConsumer(queue);
// Step 16. Start the JMS Connection. This step will activate the subscribers to receive messages.
connection.start();
// Step 17. Receive the messages. It's important to ACK for messages as HornetQ will not read messages from
// paging
// until messages are ACKed
for (int i = 0; i < 1000; i++)
{
message = (BytesMessage)messageConsumer.receive(3000);
if (i % 100 == 0)
{
System.out.println("Received " + i + " messages");
message.acknowledge();
}
}
message.acknowledge();
// Step 18. Receive the messages from the Queue names pageQueue. Create the proper consumer for that
messageConsumer.close();
messageConsumer = session.createConsumer(pageQueue);
for (int i = 0; i < 20; i++)
{
message = (BytesMessage)messageConsumer.receive(1000);
System.out.println("Received message " + i + " from pageQueue");
message.acknowledge();
}
return true;
}
finally
{
// And finally, always remember to close your JMS connections after use, in a finally block. Closing a JMS
// connection will automatically close all of its sessions, consumers, producer and browser objects
if (initialContext != null)
{
initialContext.close();
}
if (connection != null)
{
connection.close();
}
}
}
}