org.apache.activemq.artemis.jms.example.ZookeeperSinglePairFailback Maven / Gradle / Ivy
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package org.apache.activemq.artemis.jms.example;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.JMSException;
import javax.jms.MessageConsumer;
import javax.jms.MessageProducer;
import javax.jms.Queue;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.InitialContext;
import org.apache.activemq.artemis.util.ServerUtil;
/**
* Example of live and replicating backup pair using Zookeeper as the quorum provider.
*
* After both servers are started, the live server is killed and the backup becomes active ("fails-over").
*
* Later the live server is restarted and takes back its position by asking the backup to stop ("fail-back").
*/
public class ZookeeperSinglePairFailback {
private static Process server0;
private static Process server1;
public static void main(final String[] args) throws Exception {
// Step 0. Prepare Zookeeper Evironment as shown on readme.md
final int numMessages = 30;
Connection connection = null;
InitialContext initialContext = null;
try {
server0 = ServerUtil.startServer(args[0], ZookeeperSinglePairFailback.class.getSimpleName() + "-primary", 0, 30000);
server1 = ServerUtil.startServer(args[1], ZookeeperSinglePairFailback.class.getSimpleName() + "-backup", 1, 10000);
// Step 2. Get an initial context for looking up JNDI from the server #1
initialContext = new InitialContext();
// Step 3. Look up the JMS resources from JNDI
Queue queue = (Queue) initialContext.lookup("queue/exampleQueue");
ConnectionFactory connectionFactory = (ConnectionFactory) initialContext.lookup("ConnectionFactory");
// Step 4. Create a JMS Connection
connection = connectionFactory.createConnection();
// Step 5. Create a *non-transacted* JMS Session with client acknowledgement
Session session = connection.createSession(false, Session.CLIENT_ACKNOWLEDGE);
// Step 6. Start the connection to ensure delivery occurs
connection.start();
// Step 7. Create a JMS MessageProducer and a MessageConsumer
MessageProducer producer = session.createProducer(queue);
MessageConsumer consumer = session.createConsumer(queue);
// Step 8. Send some messages to server #1, the live server
for (int i = 0; i < numMessages; i++) {
TextMessage message = session.createTextMessage("This is text message " + i);
producer.send(message);
System.out.println("Sent message: " + message.getText());
}
// Step 9. Receive and acknowledge a third of the sent messages
TextMessage message0 = null;
for (int i = 0; i < numMessages / 3; i++) {
message0 = (TextMessage) consumer.receive(5000);
System.out.println("Got message: " + message0.getText());
}
message0.acknowledge();
System.out.println("Received and acknowledged a third of the sent messages");
// Step 10. Receive the rest third of the sent messages but *do not* acknowledge them yet
for (int i = numMessages / 3; i < numMessages; i++) {
message0 = (TextMessage) consumer.receive(5000);
System.out.println("Got message: " + message0.getText());
}
System.out.println("Received without acknowledged the rest of the sent messages");
Thread.sleep(2000);
// Step 11. Crash server #0, the live server, and wait a little while to make sure
// it has really crashed
ServerUtil.killServer(server0);
System.out.println("Killed primary");
Thread.sleep(2000);
// Step 12. Acknowledging the received messages will fail as failover to the backup server has occurred
try {
message0.acknowledge();
} catch (JMSException e) {
System.out.println("Got (the expected) exception while acknowledging message: " + e.getMessage());
}
// Step 13. Consume again the 2nd third of the messages again. Note that they are not considered as redelivered.
for (int i = numMessages / 3; i < (numMessages / 3) * 2; i++) {
message0 = (TextMessage) consumer.receive(5000);
System.out.printf("Got message: %s (redelivered?: %s)\n", message0.getText(), message0.getJMSRedelivered());
}
// Step 14. Acknowledging them on the failed-over broker works fine
message0.acknowledge();
System.out.println("Acknowledged 2n third of messages");
// Step 15. Restarting primary
server0 = ServerUtil.startServer(args[0], ZookeeperSinglePairFailback.class.getSimpleName() + "-primary", 0, 10000);
System.out.println("Started primary");
// await fail-back to complete
Thread.sleep(4000);
// Step 16. Consuming the 3rd third of the messages. Note that they are not considered as redelivered.
for (int i = (numMessages / 3) * 2; i < numMessages; i++) {
message0 = (TextMessage) consumer.receive(5000);
System.out.printf("Got message: %s (redelivered?: %s)\n", message0.getText(), message0.getJMSRedelivered());
}
message0.acknowledge();
System.out.println("Acknowledged 3d third of messages");
} finally {
// Step 17. Be sure to close our resources!
if (connection != null) {
connection.close();
}
if (initialContext != null) {
initialContext.close();
}
ServerUtil.killServer(server0);
ServerUtil.killServer(server1);
// Step 18. stop the ZK server
}
}
}