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Log4j JMS appender can be used to send your log messages to JMS broker. To use ActiveMQ as a destination of your messages, you need to configure JMS appender properly. The code sample below shows example configuration: log4j.rootLogger=INFO, stdout, jms ## Be sure that ActiveMQ messages are not logged to 'jms' appender log4j.logger.org.apache.activemq=INFO, stdout log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.layout=org.apache.log4j.PatternLayout log4j.appender.stdout.layout.ConversionPattern=%d %-5p %c - %m%n ## Configure 'jms' appender. You'll also need jndi.properties file in order to make it work log4j.appender.jms=org.apache.log4j.net.JMSAppender log4j.appender.jms.InitialContextFactoryName=org.apache.activemq.jndi.ActiveMQInitialContextFactory log4j.appender.jms.ProviderURL=tcp://localhost:61616 log4j.appender.jms.TopicBindingName=logTopic log4j.appender.jms.TopicConnectionFactoryBindingName=ConnectionFactory The important thing is not to send ActiveMQ logs to JMS appender, as it can cause errors since the broker will want to log before the connection is established. You will also need a JNDI configuration, so that appender can find appropriate topic to send log messages to. The example topic.logTopic=logTopic Finally, you can subscribe to the topic and listen for log messages:
public class Log4jJMSAppenderExample implements MessageListener {
public Log4jJMSAppenderExample() throws Exception {
// create a logTopic topic consumer
ActiveMQConnectionFactory factory = new ActiveMQConnectionFactory("tcp://localhost:61616");
Connection conn = factory.createConnection();
Session sess = conn.createSession(false, Session.AUTO_ACKNOWLEDGE);
conn.start();
MessageConsumer consumer = sess.createConsumer(sess.createTopic("logTopic"));
consumer.setMessageListener(this);
// log a message
Logger log = Logger.getLogger(Log4jJMSAppenderExample.class);
log.info("Test log");
// clean up
Thread.sleep(1000);
consumer.close();
sess.close();
conn.close();
System.exit(1);
}
public static void main(String[] args) throws Exception {
new Log4jJMSAppenderExample();
}
public void onMessage(Message message) {
try {
// receive log event in your consumer
LoggingEvent event = (LoggingEvent)((ActiveMQObjectMessage)message).getObject();
System.out.println("Received log [" + event.getLevel() + "]: "+ event.getMessage());
} catch (Exception e) {
e.printStackTrace();
}
}
}
Note that appender send logging event wrapped in an object message, so you can extract information such as logger name, level and of course the message. Starting with ActiveMQ 5.3, this example is included in the standard distribution. You can run it by executing ant log4j-jms inside
log4j-jms:
[echo] Running a Log4j JMS Appender example
[java] 2009-08-11 13:58:46,767 INFO Log4jJMSAppenderExample - Test log
[java] Received log [INFO]: Test log
[java] Java Result: 1
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