The use of message header fields
/*
* @(#)MessageHeadersTopic.java 1.3 02/05/02
*
* Copyright (c) 2000-2002 Sun Microsystems, Inc. All Rights Reserved.
*
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* which is disparaging to Sun.
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* facility. Licensee represents and warrants that it will not use or
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*/
import java.sql.*;
import java.util.*;
import javax.jms.*;
/**
* The MessageHeadersTopic class demonstrates the use of message header fields.
* <p>
* The program contains a HeaderProducer class, a HeaderConsumer class, a
* display_headers() method that is called by both classes, a main method, and
* a method that runs the consumer and producer threads.
* <p>
* The producing class sends three messages, and the consuming class
* receives them. The program displays the message headers just before the
* send call and just after the receive so that you can see which ones are
* set by the send method.
* <p>
* Specify 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 1.8, 08/18/00
*/
public class MessageHeadersTopic {
final String CONTROL_QUEUE = "controlQueue";
String topicName = null;
int exitResult = 0;
/**
* The HeaderProducer class sends three messages, setting the JMSType
* message header field, one of three header fields that are not set by
* the send method. (The others, JMSCorrelationID and JMSReplyTo, are
* demonstrated in the RequestReplyQueue example.) It also sets a
* client property, "messageNumber".
*
* The displayHeaders method is called just before the send method.
*
* @author Kim Haase
* @version 1.8, 08/18/00
*/
public class HeaderProducer extends Thread {
/**
* Runs the thread.
*/
public void run() {
ConnectionFactory connectionFactory = null;
javax.jms.Connection connection = null;
Session session = null;
Topic topic = null;
MessageProducer msgProducer = null;
TextMessage message = null;
final String MSG_TEXT = new String("Read My Headers");
try {
connectionFactory =
SampleUtilities.getConnectionFactory();
connection =
connectionFactory.createConnection();
session = connection.createSession(false,
Session.AUTO_ACKNOWLEDGE);
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);
}
try {
/*
* Synchronize with consumer. Wait for message indicating
* that consumer is ready to receive messages.
*/
try {
SampleUtilities.receiveSynchronizeMessages("PRODUCER THREAD: ",
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);
}
// Create producer.
msgProducer = session.createProducer(topic);
// First message: no-argument form of send method
message = session.createTextMessage();
message.setJMSType("Simple");
System.out.println("PRODUCER THREAD: Setting JMSType to "
+ message.getJMSType());
message.setIntProperty("messageNumber", 1);
System.out.println("PRODUCER THREAD: Setting client property messageNumber to "
+ message.getIntProperty("messageNumber"));
message.setText(MSG_TEXT);
System.out.println("PRODUCER THREAD: Setting message text to: "
+ message.getText());
System.out.println("PRODUCER THREAD: Headers before message is sent:");
displayHeaders(message, "PRODUCER THREAD: ");
msgProducer.send(message);
/*
* Second message: 3-argument form of send method;
* explicit setting of delivery mode, priority, and
* expiration
*/
message = session.createTextMessage();
message.setJMSType("Less Simple");
System.out.println("\nPRODUCER THREAD: Setting JMSType to "
+ message.getJMSType());
message.setIntProperty("messageNumber", 2);
System.out.println("PRODUCER THREAD: Setting client property messageNumber to "
+ message.getIntProperty("messageNumber"));
message.setText(MSG_TEXT + " Again");
System.out.println("PRODUCER THREAD: Setting message text to: "
+ message.getText());
displayHeaders(message, "PRODUCER THREAD: ");
msgProducer.send(message, DeliveryMode.NON_PERSISTENT,
3, 10000);
/*
* Third message: no-argument form of send method,
* MessageID and Timestamp disabled
*/
message = session.createTextMessage();
message.setJMSType("Disable Test");
System.out.println("\nPRODUCER THREAD: Setting JMSType to "
+ message.getJMSType());
message.setIntProperty("messageNumber", 3);
System.out.println("PRODUCER THREAD: Setting client property messageNumber to "
+ message.getIntProperty("messageNumber"));
message.setText(MSG_TEXT
+ " with MessageID and Timestamp disabled");
System.out.println("PRODUCER THREAD: Setting message text to: "
+ message.getText());
msgProducer.setDisableMessageID(true);
msgProducer.setDisableMessageTimestamp(true);
System.out.println("PRODUCER THREAD: Disabling Message ID and Timestamp");
displayHeaders(message, "PRODUCER THREAD: ");
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 HeaderConsumer class receives the three messages and calls the
* displayHeaders method to show how the send method changed the
* header values.
* <p>
* The first message, in which no fields were set explicitly by the send
* method, shows the default values of these fields.
* <p>
* The second message shows the values set explicitly by the send method.
* <p>
* The third message shows whether disabling the MessageID and Timestamp
* has any effect in the current JMS implementation.
*
* @author Kim Haase
* @version 1.8, 08/18/00
*/
public class HeaderConsumer extends Thread {
/**
* Runs the thread.
*/
public void run() {
ConnectionFactory connectionFactory = null;
javax.jms.Connection connection = null;
Session session = null;
Topic topic = null;
MessageConsumer msgConsumer = null;
final boolean NOLOCAL = true;
TextMessage message = null;
try {
connectionFactory =
SampleUtilities.getConnectionFactory();
connection =
connectionFactory.createConnection();
session = connection.createSession(false,
Session.AUTO_ACKNOWLEDGE);
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 consumer and start message delivery.
* Send synchronize message to producer.
* Receive the three messages.
* Call the displayHeaders method to display the message headers.
*/
try {
msgConsumer =
session.createConsumer(topic, null, NOLOCAL);
connection.start();
// Let producer know that consumer is ready.
try {
SampleUtilities.sendSynchronizeMessage("CONSUMER THREAD: ",
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);
}
for (int i = 0; i < 3; i++) {
message = (TextMessage) msgConsumer.receive();
System.out.println("\nCONSUMER THREAD: Message received: "
+ message.getText());
System.out.println("CONSUMER THREAD: Headers after message is received:");
displayHeaders(message, "CONSUMER THREAD: ");
}
} catch (JMSException e) {
System.out.println("Exception occurred: " + e.toString());
exitResult = 1;
} finally {
if (connection != null) {
try {
connection.close();
} catch (JMSException e) {
exitResult = 1;
}
}
}
}
}
/**
* Displays all message headers. Each display is in a try/catch block in
* case the header is not set before the message is sent.
*
* @param message the message whose headers are to be displayed
* @param prefix the prefix (producer or consumer) to be displayed
*/
public void displayHeaders (Message message, String prefix) {
Destination dest = null;
int delMode = 0;
long expiration = 0;
Time expTime = null;
int priority = 0;
String msgID = null;
long timestamp = 0;
Time timestampTime = null;
String correlID = null;
Destination replyTo = null;
boolean redelivered = false;
String type = null;
String propertyName = null;
try {
System.out.println(prefix + "Headers set by send method: ");
// Display the destination (topic, in this case).
try {
dest = message.getJMSDestination();
System.out.println(prefix + " JMSDestination: " + dest);
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
// Display the delivery mode.
try {
delMode = message.getJMSDeliveryMode();
System.out.print(prefix);
if (delMode == DeliveryMode.NON_PERSISTENT) {
System.out.println(" JMSDeliveryMode: non-persistent");
} else if (delMode == DeliveryMode.PERSISTENT) {
System.out.println(" JMSDeliveryMode: persistent");
} else {
System.out.println(" JMSDeliveryMode: neither persistent nor non-persistent; error");
}
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
/*
* Display the expiration time. If value is 0 (the default),
* the message never expires. Otherwise, cast the value
* to a Time object for display.
*/
try {
expiration = message.getJMSExpiration();
System.out.print(prefix);
if (expiration != 0) {
expTime = new Time(expiration);
System.out.println(" JMSExpiration: " + expTime);
} else {
System.out.println(" JMSExpiration: " + expiration);
}
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
// Display the priority.
try {
priority = message.getJMSPriority();
System.out.println(prefix + " JMSPriority: " + priority);
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
// Display the message ID.
try {
msgID = message.getJMSMessageID();
System.out.println(prefix + " JMSMessageID: " + msgID);
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
/*
* Display the timestamp.
* If value is not 0, cast it to a Time object for display.
*/
try {
timestamp = message.getJMSTimestamp();
System.out.print(prefix);
if (timestamp != 0) {
timestampTime = new Time(timestamp);
System.out.println(" JMSTimestamp: " + timestampTime);
} else {
System.out.println(" JMSTimestamp: " + timestamp);
}
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
// Display the correlation ID.
try {
correlID = message.getJMSCorrelationID();
System.out.println(prefix + " JMSCorrelationID: " + correlID);
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
// Display the ReplyTo destination.
try {
replyTo = message.getJMSReplyTo();
System.out.println(prefix + " JMSReplyTo: " + replyTo);
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
// Display the Redelivered value (usually false).
System.out.println(prefix + "Header set by JMS provider:");
try {
redelivered = message.getJMSRedelivered();
System.out.println(prefix + " JMSRedelivered: " + redelivered);
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
// Display the JMSType.
System.out.println(prefix + "Headers set by client program:");
try {
type = message.getJMSType();
System.out.println(prefix + " JMSType: " + type);
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
// Display any client properties.
try {
for (Enumeration e = message.getPropertyNames(); e.hasMoreElements() ;) {
propertyName = new String((String) e.nextElement());
System.out.println(prefix + " Client property "
+ propertyName + ": "
+ message.getObjectProperty(propertyName));
}
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
} catch (Exception e) {
System.out.println(prefix + "Exception occurred: "
+ e.toString());
exitResult = 1;
}
}
/**
* Instantiates the consumer and producer classes and starts their
* threads.
* Calls the join method to wait for the threads to die.
* <p>
* It is essential to start the consumer before starting the producer.
* In the send/subscribe model, a consumer can ordinarily receive only
* messages sent while it is active.
*/
public void run_threads() {
HeaderConsumer headerConsumer = new HeaderConsumer();
HeaderProducer headerProducer = new HeaderProducer();
headerConsumer.start();
headerProducer.start();
try {
headerConsumer.join();
headerProducer.join();
} catch (InterruptedException e) {}
}
/**
* Reads the topic name 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) {
MessageHeadersTopic mht = new MessageHeadersTopic();
if (args.length != 1) {
System.out.println("Usage: java MessageHeadersTopic <topic_name>");
System.exit(1);
}
mht.topicName = new String(args[0]);
System.out.println("Topic name is " + mht.topicName);
mht.run_threads();
SampleUtilities.exit(mht.exitResult);
}
}
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