A message will not be acknowledged until processing of it is complete : Java Message Service JMS « J2EE « Java
A message will not be acknowledged until processing of it is complete
/*
* @(#)AckEquivExample.java 1.3 02/05/02
*
* Copyright (c) 2000-2002 Sun Microsystems, Inc. All Rights Reserved.
*
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* modify and redistribute this software in source and binary code form,
* provided that i) this copyright notice and license appear on all copies of
* the software; and ii) Licensee does not utilize the software in a manner
* which is disparaging to Sun.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
* IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
* NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
* LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
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* LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
* INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
* CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
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*
* This software is not designed or intended for use in on-line control of
* aircraft, air traffic, aircraft navigation or aircraft communications; or in
* the design, construction, operation or maintenance of any nuclear
* facility. Licensee represents and warrants that it will not use or
* redistribute the Software for such purposes.
*/
import javax.jms.*;
/**
* The AckEquivExample class shows how the following two scenarios both ensure
* that a message will not be acknowledged until processing of it is complete:
* <ul>
* <li> Using an asynchronous consumer (message listener) in an
* AUTO_ACKNOWLEDGE session
* <li> Using a synchronous consumer in a CLIENT_ACKNOWLEDGE session
* </ul>
* <p>
* With a message listener, the automatic acknowledgment happens when the
* onMessage method returns -- that is, after message processing has finished.
* <p>
* With a synchronous receive, the client acknowledges the message after
* processing is complete. (If you use AUTO_ACKNOWLEDGE with a synchronous
* receive, the acknowledgement happens immediately after the receive call; if
* any subsequent processing steps fail, the message cannot be redelivered.)
* <p>
* The program contains a SynchProducer class, a SynchConsumer class, an
* AsynchSubscriber class with a TextListener class, a MultiplePublisher class,
* a main method, and a method that runs the other classes' threads.
* <p>
* Specify a queue name and a topic name on the command line when you run the
* program. The program also uses a queue named "controlQueue", which should be
* created before you run the program.
*
* @author Kim Haase
* @version 1.6, 08/18/00
*/
public class AckEquivExample {
final String CONTROL_QUEUE = "controlQueue";
String queueName = null;
String topicName = null;
int exitResult = 0;
/**
* The SynchProducer class creates a session in CLIENT_ACKNOWLEDGE mode and
* sends a message.
*
* @author Kim Haase
* @version 1.6, 08/18/00
*/
public class SynchProducer extends Thread {
/**
* Runs the thread.
*/
public void run() {
ConnectionFactory connectionFactory = null;
Connection connection = null;
Session session = null;
Queue queue = null;
MessageProducer msgProducer = null;
final String MSG_TEXT =
new String("Here is a client-acknowledge message");
TextMessage message = null;
try {
connectionFactory =
SampleUtilities.getConnectionFactory();
connection =
connectionFactory.createConnection();
session = connection.createSession(false,
Session.CLIENT_ACKNOWLEDGE);
queue = SampleUtilities.getQueue(queueName, session);
} catch (Exception e) {
System.out.println("Connection problem: " + e.toString());
if (connection != null) {
try {
connection.close();
} catch (JMSException ee) {}
}
System.exit(1);
}
/*
* Create client-acknowledge producer.
* Create and send message.
*/
try {
System.out.println("PRODUCER: Created client-acknowledge session");
msgProducer = session.createProducer(queue);
message = session.createTextMessage();
message.setText(MSG_TEXT);
System.out.println("PRODUCER: Sending message: "
+ message.getText());
msgProducer.send(message);
} catch (JMSException e) {
System.out.println("Exception occurred: " + e.toString());
exitResult = 1;
} finally {
if (connection != null) {
try {
connection.close();
} catch (JMSException e) {
exitResult = 1;
}
}
}
}
}
/**
* The SynchConsumer class creates a session in CLIENT_ACKNOWLEDGE mode and
* receives the message sent by the SynchProducer class.
*
* @author Kim Haase
* @version 1.6, 08/18/00
*/
public class SynchConsumer extends Thread {
/**
* Runs the thread.
*/
public void run() {
ConnectionFactory connectionFactory = null;
Connection connection = null;
Session session = null;
Queue queue = null;
MessageConsumer msgConsumer = null;
TextMessage message = null;
try {
connectionFactory =
SampleUtilities.getConnectionFactory();
connection =
connectionFactory.createConnection();
session = connection.createSession(false,
Session.CLIENT_ACKNOWLEDGE);
queue = SampleUtilities.getQueue(queueName, session);
} catch (Exception e) {
System.out.println("Connection problem: " + e.toString());
if (connection != null) {
try {
connection.close();
} catch (JMSException ee) {}
}
System.exit(1);
}
/*
* Create client-acknowledge consumer.
* Receive message and process it.
* Acknowledge message.
*/
try {
System.out.println("CONSUMER: Created client-acknowledge session");
msgConsumer = session.createConsumer(queue);
connection.start();
message = (TextMessage) msgConsumer.receive();
System.out.println("CONSUMER: Processing message: "
+ message.getText());
System.out.println("CONSUMER: Now I'll acknowledge the message");
message.acknowledge();
} catch (JMSException e) {
System.out.println("Exception occurred: " + e.toString());
exitResult = 1;
} finally {
if (connection != null) {
try {
connection.close();
} catch (JMSException e) {
exitResult = 1;
}
}
}
}
}
/**
* The AsynchSubscriber class creates a session in AUTO_ACKNOWLEDGE mode
* and fetches several messages from a topic asynchronously, using a
* message listener, TextListener.
* <p>
* Each message is acknowledged after the onMessage method completes.
*
* @author Kim Haase
* @version 1.6, 08/18/00
*/
public class AsynchSubscriber extends Thread {
/**
* The TextListener class implements the MessageListener interface by
* defining an onMessage method for the AsynchSubscriber class.
*
* @author Kim Haase
* @version 1.6, 08/18/00
*/
private class TextListener implements MessageListener {
final SampleUtilities.DoneLatch monitor =
new SampleUtilities.DoneLatch();
/**
* Casts the message to a TextMessage and displays its text.
* A non-text message is interpreted as the end of the message
* stream, and the message listener sets its monitor state to all
* done processing messages.
*
* @param message the incoming message
*/
public void onMessage(Message message) {
if (message instanceof TextMessage) {
TextMessage msg = (TextMessage) message;
try {
System.out.println("CONSUMER: Processing message: "
+ msg.getText());
} catch (JMSException e) {
System.out.println("Exception in onMessage(): "
+ e.toString());
}
} else {
monitor.allDone();
}
}
}
/**
* Runs the thread.
*/
public void run() {
ConnectionFactory connectionFactory = null;
Connection connection = null;
Session session = null;
Topic topic = null;
TopicSubscriber topicSubscriber = null;
TextListener topicListener = null;
try {
connectionFactory =
SampleUtilities.getConnectionFactory();
connection =
connectionFactory.createConnection();
connection.setClientID("AckEquivExample");
session = connection.createSession(false,
Session.AUTO_ACKNOWLEDGE);
System.out.println("CONSUMER: Created auto-acknowledge session");
topic = SampleUtilities.getTopic(topicName, session);
} catch (Exception e) {
System.out.println("Connection problem: " + e.toString());
if (connection != null) {
try {
connection.close();
} catch (JMSException ee) {}
}
System.exit(1);
}
/*
* Create auto-acknowledge subscriber.
* Register message listener (TextListener).
* Start message delivery.
* Send synchronize message to publisher, then wait till all
* messages have arrived.
* Listener displays the messages obtained.
*/
try {
topicSubscriber = session.createDurableSubscriber(topic,
"AckEquivExampleSubscription");
topicListener = new TextListener();
topicSubscriber.setMessageListener(topicListener);
connection.start();
// Let publisher know that subscriber is ready.
try {
SampleUtilities.sendSynchronizeMessage("CONSUMER: ",
CONTROL_QUEUE);
} catch (Exception e) {
System.out.println("Queue probably missing: " + e.toString());
if (connection != null) {
try {
connection.close();
} catch (JMSException ee) {}
}
System.exit(1);
}
/*
* Asynchronously process messages.
* Block until publisher issues a control message indicating
* end of publish stream.
*/
topicListener.monitor.waitTillDone();
topicSubscriber.close();
session.unsubscribe("AckEquivExampleSubscription");
} catch (JMSException e) {
System.out.println("Exception occurred: " + e.toString());
exitResult = 1;
} finally {
if (connection != null) {
try {
connection.close();
} catch (JMSException e) {
exitResult = 1;
}
}
}
}
}
/**
* The MultiplePublisher class creates a session in AUTO_ACKNOWLEDGE mode
* and publishes three messages to a topic.
*
* @author Kim Haase
* @version 1.6, 08/18/00
*/
public class MultiplePublisher extends Thread {
/**
* Runs the thread.
*/
public void run() {
ConnectionFactory connectionFactory = null;
Connection connection = null;
Session session = null;
Topic topic = null;
MessageProducer topicPublisher = null;
TextMessage message = null;
final int NUMMSGS = 3;
final String MSG_TEXT =
new String("Here is an auto-acknowledge message");
try {
connectionFactory =
SampleUtilities.getConnectionFactory();
connection =
connectionFactory.createConnection();
session = connection.createSession(false,
Session.AUTO_ACKNOWLEDGE);
System.out.println("PRODUCER: Created auto-acknowledge session");
topic = SampleUtilities.getTopic(topicName, session);
} catch (Exception e) {
System.out.println("Connection problem: " + e.toString());
if (connection != null) {
try {
connection.close();
} catch (JMSException ee) {}
}
System.exit(1);
}
/*
* After synchronizing with subscriber, create publisher.
* Send 3 messages, varying text slightly.
* Send end-of-messages message.
*/
try {
/*
* Synchronize with subscriber. Wait for message indicating
* that subscriber is ready to receive messages.
*/
try {
SampleUtilities.receiveSynchronizeMessages("PRODUCER: ",
CONTROL_QUEUE, 1);
} catch (Exception e) {
System.out.println("Queue probably missing: " + e.toString());
if (connection != null) {
try {
connection.close();
} catch (JMSException ee) {}
}
System.exit(1);
}
topicPublisher = session.createProducer(topic);
message = session.createTextMessage();
for (int i = 0; i < NUMMSGS; i++) {
message.setText(MSG_TEXT + " " + (i + 1));
System.out.println("PRODUCER: Publishing message: "
+ message.getText());
topicPublisher.send(message);
}
// Send a non-text control message indicating end of messages.
topicPublisher.send(session.createMessage());
} catch (JMSException e) {
System.out.println("Exception occurred: " + e.toString());
exitResult = 1;
} finally {
if (connection != null) {
try {
connection.close();
} catch (JMSException e) {
exitResult = 1;
}
}
}
}
}
/**
* Instantiates the producer, consumer, subscriber, and publisher classes and
* starts their threads.
* Calls the join method to wait for the threads to die.
*/
public void run_threads() {
SynchProducer synchProducer = new SynchProducer();
SynchConsumer synchConsumer = new SynchConsumer();
AsynchSubscriber asynchSubscriber = new AsynchSubscriber();
MultiplePublisher multiplePublisher = new MultiplePublisher();
synchProducer.start();
synchConsumer.start();
try {
synchProducer.join();
synchConsumer.join();
} catch (InterruptedException e) {}
asynchSubscriber.start();
multiplePublisher.start();
try {
asynchSubscriber.join();
multiplePublisher.join();
} catch (InterruptedException e) {}
}
/**
* Reads the queue and topic names from the command line, then calls the
* run_threads method to execute the program threads.
*
* @param args the topic used by the example
*/
public static void main(String[] args) {
AckEquivExample aee = new AckEquivExample();
if (args.length != 2) {
System.out.println("Usage: java AckEquivExample <queue_name> <topic_name>");
System.exit(1);
}
aee.queueName = new String(args[0]);
aee.topicName = new String(args[1]);
System.out.println("Queue name is " + aee.queueName);
System.out.println("Topic name is " + aee.topicName);
aee.run_threads();
SampleUtilities.exit(aee.exitResult);
}
}
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