A Message Acknowledgment Example

The AckEquivExample.java program shows how both of the following two scenarios ensure that a message will not be acknowledged until processing of it is complete:

• Using an asynchronous message consumer (a message listener) in an AUTO_ACKNOWLEDGE session

• Using a synchronous receiver in a CLIENT_ACKNOWLEDGE session

With a message listener, the automatic acknowledgment happens when the onMessage method returns (that is, after message processing has finished). With a synchronous receiver, the client acknowledges the message after processing is complete. If you use AUTO_ACKNOWLEDGE with a synchronous receive, the acknowledgment happens immediately after the receive call; if any subsequent processing steps fail, the message cannot be redelivered.

The program is in the following directory:

tut-install/javaeetutorial5/examples/jms/advanced/ackequivexample/src/java/

The program contains a SynchSender class, a SynchReceiver class, an AsynchSubscriber class with a TextListener class, a MultiplePublisher class, a main method, and a method that runs the other classes’ threads.

The program uses the following objects:

• jms/ConnectionFactory, jms/Queue, and jms/Topic: resources that you created in Creating JMS Administered Objects for the Synchronous Receive Example

• jms/ControlQueue: an additional queue

• jms/DurableConnectionFactory: a connection factory with a client ID (see Creating Durable Subscriptions, for more information)

To create the new queue and connection factory, you can use Ant targets defined in the file tut-install/javaeetutorial5/examples/jms/advanced/ackequivexample/build.xml.

To run this example, follow these steps:

1. In a terminal window, go to the following directory:

   tut-install/javaeetutorial5/examples/jms/advanced/ackequivexample/
   

2. To create the objects needed in this example, type the following commands:

   ant create-control-queue ant create-durable-cf

3. To compile and package the program using NetBeans IDE, follow these steps:

   1. In NetBeans IDE, choose Open Project from the File menu.

   2. In the Open Project dialog, navigate to tut-install/javaeetutorial5/examples/jms/advanced/.

   3. Select the ackequivexample folder.

   4. Select the Open as Main Project check box.

   5. Click Open Project.

   6. Right-click the project and choose Build.

   To compile and package the program using Ant, type the following command:

   ant

4. To run the program using NetBeans IDE, right-click the ackequivexample project and choose Run.

   To run the program from the command line, follow these steps:

   1. Go to the dist directory:

      cd dist

   2. Type the following command:

      appclient -client ackequivexample.jar

The program output looks something like this:

Queue name is jms/ControlQueue
Queue name is jms/Queue
Topic name is jms/Topic
Connection factory name is jms/DurableConnectionFactory
  SENDER: Created client-acknowledge session
  SENDER: Sending message: Here is a client-acknowledge message
  RECEIVER: Created client-acknowledge session
  RECEIVER: Processing message: Here is a client-acknowledge message
  RECEIVER: Now I’ll acknowledge the message
SUBSCRIBER: Created auto-acknowledge session
SUBSCRIBER: Sending synchronize message to control queue
PUBLISHER: Created auto-acknowledge session
PUBLISHER: Receiving synchronize messages from control queue; count = 1
PUBLISHER: Received synchronize message;  expect 0 more
PUBLISHER: Publishing message: Here is an auto-acknowledge message 1
PUBLISHER: Publishing message: Here is an auto-acknowledge message 2
SUBSCRIBER: Processing message: Here is an auto-acknowledge message 1
PUBLISHER: Publishing message: Here is an auto-acknowledge message 3
SUBSCRIBER: Processing message: Here is an auto-acknowledge message 2
SUBSCRIBER: Processing message: Here is an auto-acknowledge message 3

After you run the program, you can delete the destination resource jms/ControlQueue. Go to the directory tut-install/javaeetutorial5/examples/jms/advanced/ackequivexample/ and type the following command:

ant delete-control-queue

You will need the other resources for other examples.

To delete the class and JAR files for the program using NetBeans IDE, right-click the project and choose Clean.

To delete the class and JAR files for the program using Ant, type the following:

ant clean