Client Acknowledgement Example

The following code shows the use of client acknowledgement and session recovery.

You will notice messages are not acknowledged unless you explicitly say so.

It does two passes of the messages, the first does not acknowledge, the seconds does.

The second pass is achieved by invoking

session.recover()

to force redelivery of

unacknowledged messages.

  Code

import java.util.Properties;

import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.Queue;
import javax.jms.QueueConnection;
import javax.jms.QueueConnectionFactory;
import javax.jms.QueueReceiver;
import javax.jms.QueueSender;
import javax.jms.QueueSession;
import javax.jms.Session;

import javax.jms.TextMessage;
import javax.naming.Context;
import javax.naming.InitialContext;

public class Client implements MessageListener
{
   public static void main(String[] args)  throws Exception
   {
      log.info("Creating jndi context - alternatively use a jndi.properties");
      Properties properties = new Properties();
      properties.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
      properties.put(Context.URL_PKG_PREFIXES, "org.jnp.interfaces");
      properties.put(Context.PROVIDER_URL, "localhost");
      InitialContext ctx = new InitialContext(properties);

      log.info("Looking up queue");
      Queue queue = (Queue) ctx.lookup("queue/testQueue");

      log.info("Looking up connection factory");
      QueueConnectionFactory qcf = (QueueConnectionFactory) ctx.lookup("UIL2ConnectionFactory");

      log.info("Creating connection");
      QueueConnection qc = qcf.createQueueConnection();
      try
      {
         log.info("Creating session");
         QueueSession qs = qc.createQueueSession(false, Session.CLIENT_ACKNOWLEDGE);
         
         log.info("Creating sender");
         QueueSender sender = qs.createSender(queue);

         log.info("Creating messages");
         TextMessage hello = qs.createTextMessage("hello");
         TextMessage goodbye = qs.createTextMessage("goodbye");

         log.info("Sending messages");
         sender.send(hello);
         sender.send(goodbye);

         log.info("Creating receiver");
         QueueReceiver receiver = qs.createReceiver(queue);

         log.info("You have to start the connection before receiving messages");
         qc.start();

         log.info("Set the message listener");
         receiver.setMessageListener(new Client(qs));

         log.info("Allowing the message listener 10 seconds to receive messages");
         Thread.sleep(10000);
      }
      finally
      {
         qc.close();
      }
   }

   QueueSession session;

   public Client(QueueSession session)
   {
      this.session = session;
   }

   public void onMessage(Message message)
   {
      try
      {
         TextMessage tm = (TextMessage) message;
         String text = tm.getText();
         boolean redelivered = message.getJMSRedelivered();

         log.info("Got message: " + text + " redelivered=" + redelivered);

         if (redelivered)
         {
            log.info("This is the second pass, do a client acknowledgment");
            message.acknowledge();
            return;
         }

         if (text.equals("goodbye"))
         {
            log.info("Got the last message, recover the session forcing redelivery of all messages");
            session.recover();
         }
      }
      catch (JMSException e)
      {
         log.error("Got unexpected error", e);
         System.exit(0);
      }
   }

   public static class log
   {
      public static void info(String message)
      {
         System.out.println(message);
      }

      public static void error(String message, Throwable t)
      {
         System.err.println(message);
         t.printStackTrace();
      }
   }
}

Instructions

To compile it:
javac -classpath JBOSS_HOME/client/jbossall-client.jar Client.java
or windows
javac -classpath JBOSS_HOME\client\jbossall-client.jar Client.java

To run it:
java -classpath .:JBOSS_HOME/client/jbossall-client.jar Client
or windows
java -classpath .;JBOSS_HOME\client\jbossall-client.jar Client

Output

Creating jndi context - alternatively use a jndi.properties
Looking up queue
Looking up connection factory
Creating connection
Creating session
Creating sender
Creating messages
Sending messages
Creating receiver
You have to start the connection before receiving messages
Set the message listener
Got message: hello redelivered=false
Got message: goodbye redelivered=false
Got the last message, recover the session forcing redelivery of all messages
Got message: hello redelivered=true
This is the second pass, do a client acknowledgment
Got message: goodbye redelivered=true
This is the second pass, do a client acknowledgment
Allowing the message listener 10 seconds to receive messages

Things to try

Change CLIENT_ACKNOWLEDGE to AUTO_ACKNOWLEDGE

and remove the

message.acknowledge()

statement

to see the difference between client and auto acknowledgement.