Posts tagged Java

As per my last post, we are currently looking into migrating from ActiveMQ towards HornetQ. One of the missing features which we used and depend on are dynamic queues and topics. Our main goal is to avoid touching any java code and depend solely on Spring configuration changes.

Non dynamic destination configuration through spring

<bean name="myDestination" class="org.hornetq.api.jms.HornetQJMSClient" factory-method="createQueue">
   <constructor-arg index="0" value="ExampleQueue"/>
</bean>
<bean name="jmsTemplate">
   <property name="connectionFactory" ref="connectionFactory"/>
   <property name="defaultDestination" ref="myDestination"/>
</bean>

In the above example, the queue TestQueue will already need to be defined on your HornetQ server.

Dynamic creation through a Spring FactoryBean implementation

Using a simple FactoryBean implementation and the HornetQ management api, we can achieve dynamic destination creation.

<bean name="myDestination" class="com.mikem.HornetQueueFactory">
   <property name="name" value="TestQueue"/>
</bean>
<bean name="jmsTemplate">
   <property name="connectionFactory" ref="connectionFactory"/>
   <property name="defaultDestination" ref="myDestination"/>
</bean>

Notice the different class used to define the myDestination bean. This is a simple implementation of a Spring FactoryBean.

 public class HornetQueueFactory implements FactoryBean {
	private String name;

	@Override
	public Class getObjectType() {
		return Queue.class;
	}

	@Override
	public boolean isSingleton() {
		return true;
	}

	@SuppressWarnings("unchecked")
	@Override
	public Queue getObject() throws Exception {
		boolean created = false;

        ObjectName on = ObjectNameBuilder.DEFAULT.getJMSServerObjectName();
        JMXConnector connector = JMXConnectorFactory.connect(new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:1097/jmxrmi"), new HashMap());
        MBeanServerConnection mbsc = connector.getMBeanServerConnection();
        JMSServerControl serverControl = (JMSServerControl)MBeanServerInvocationHandler.newProxyInstance(mbsc, on, JMSServerControl.class, false);

        String[] queueNames = serverControl.getQueueNames();
        if (!ArrayUtils.contains(queueNames, this.name)){
        	created = serverControl.createQueue(name);
        	System.out.println("Created new queue with name " + name);
        } else {
        	created = true;
        }

        if (!created) {
        	throw new RuntimeException("Queue isn't created. Not sure why.");
        }

        return HornetQJMSClient.createQueue(name);
	}

	@Required
	public void setName(String name) {
		this.name = name;
	}}

Notes:

• JMX/RMI needs to be configured and on for this to work
• Obviously, this is a naive implementation only used to see if it could be done.
• Once it’s all cleaned up, I will probably use a single factory for both Queues and Topics