This example shows how to receive management notifications from ActiveMQ Artemis using JMS Messages.
ActiveMQ Artemis servers emit management notifications when events of interest occur (consumers are created or closed,
destinations are created or deleted, security authentication fails, etc.).
These notifications can be received either by using JMX (see JMX example) or by receiving JMS Messages
from a well-known destination.
This example will setup a JMS MessageListener to receive management notifications. We will also perform normal JMS operations to see the kind of notifications they trigger.
ActiveMQ Artemis can configured to send JMS messages when management notifications are emitted on the server.
By default, the management name is called activemq.notifications
but this can be configured in broker.xml.
For this example, we will set it to jms.topic.notificationsTopic
to be able to receive notifications from a JMS Topic.
<management-notification-address>jms.topic.notificationsTopic</management-notification-address>
Since we want to lookup the notifications topic using JNDI, we also declare it in activemq-jms.xml
<topic name="notificationsTopic">
<entry name="/topic/notificationsTopic"/>
</topic>
The notification queue requires permission to create/delete temporary queues and consume messages. This is also configured in broker.xml
<security-setting match="jms.topic.notificationsTopic">
<permission type="consume" roles="guest"/>
<permission type="createNonDurableQueue" roles="guest"/>
<permission type="deleteNonDurableQueue" roles="guest"/>
</security-setting>
To run the example, simply type mvn verify -Pexample
from this directory
InitialContext initialContext = getContext(0);
Queue queue = (Queue) initialContext.lookup("/queue/exampleQueue");
ConnectionFactory cf = (ConnectionFactory) initialContext.lookup("/ConnectionFactory");
connection = cf.createConnection();
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
MessageProducer producer = session.createProducer(queue);
Topic notificationsTopic = (Topic) initialContext.lookup("/topic/notificationsTopic");
MessageConsumer notificationConsumer = session.createConsumer(notificationsTopic);
notificationConsumer.setMessageListener(new MessageListener()
{
public void onMessage(Message notif)
{
System.out.println("------------------------");
System.out.println("Received notification:");
try
{
Enumeration propertyNames = notif.getPropertyNames();
while (propertyNames.hasMoreElements())
{
String propertyName = (String)propertyNames.nextElement();
System.out.format(" %s: %s\n", propertyName, notif.getObjectProperty(propertyName));
}
}
catch (JMSException e)
{
}
System.out.println("------------------------");
}
});
connection.start();
Now that a message listener is setup to receive management notifications, we will perform regular JMS operations to see what kind of notifications are triggered
MessageConsumer consumer = session.createConsumer(queue);
This will generate a CONSUMER_CREATED
notification:
------------------------
Received notification:
_AMQ_RoutingName: jms.queue.exampleQueue
_AMQ_Address: jms.queue.exampleQueue
...
_AMQ_ConsumerCount: 1
...
_AMQ_NotifType: CONSUMER_CREATED
------------------------
The notification tells us that a consumer was created for the JMS queue exampleQueue
. When the notification
was emitted, this consumer was the only one for the queue
consumer.close();
This will generate a CONSUMER_CLOSED
notification:
------------------------
Received notification:
_AMQ_RoutingName: jms.queue.exampleQueue
_AMQ_Address: jms.queue.exampleQueue
...
_AMQ_ConsumerCount: 0
...
_AMQ_NotifType: CONSUMER_CLOSED
------------------------
The notification tells us that a consumer was closed for the JMS queue exampleQueue
. When the notification
was emitted, there were no other consumers on the queue
try
{
cf.createConnection("not.a.valid.user", "not.a.valid.password");
} catch (JMSException e)
{
}
This will generate a SECURITY_AUTHENTICATION_VIOLATION
notification:
------------------------
Received notification:
_AMQ_User: not.a.valid.user
...
_AMQ_NotifType: SECURITY_AUTHENTICATION_VIOLATION
------------------------
The notification tells us that a user named not.a.valid.user
failed to authenticate when creating a connection to ActiveMQ Artemis.
finally
block. Closing a JMS connection will automatically close all of its sessions, consumers, producer and browser objects
finally
{
if (initialContext != null)
{
initialContext.close();
}
if (connection != null)
{
connection.close();
}
}