Listening for queues

To listen queues you only should add the next code fragment using the @MQListener annotation.

In the @MQListener annotation you can set the next properties:

• value: Name of the listening queue, use only when listen for a fixed queue
• concurrency: Number of open connections to listening the queue, applies for fixed and temporary queues.
• connectionFactory: Name of a specific ConnectionFactory Bean, used to create the connections for this consumer.
• queueCustomizer: Name of a specific MQQueueCustomizer Bean, used to customize the listening queue properties before start the consumers.

Listening a fixed queue reactive

@MQListener("DEV.QUEUE.1")
public Mono<Void> process(Message message) throws JMSException {
  String text=((TextMessage)message).getText();
  return doSomething(text);
}

You also can set name from properties to make it dynamic configurable

@MQListener("${commons.jms.input-queue}")
public Mono<Void> process(Message message) throws JMSException {
  String text=((TextMessage)message).getText();
  return doSomething(text);
}

You also can pass specific listener settings like:

@MQListener(value = "${commons.jms.input-queue}", concurrency = "5", maxRetries = "5", connectionFactory = "domainB")
public Mono<Void> process(Message message) throws JMSException {
  String text=((TextMessage)message).getText();
  return doSomething(text);
}

Listening a fixed queue non reactive

In this case the main difference is the return type of the annotated method, in reactive should be Mono<Void> and the method should return the reactive flow resolving a Mono<Void>. In non reactive must be void and in this case no return value is required

@MQListener("DEV.QUEUE.1")
public void process(Message message) throws JMSException {
  String text=((TextMessage)message).getText();
  doSomething(text);
}

Connection Architecture

This sample will listen for a fixed queue named DEV.QUEUE.1, the JMS objects structure will be like this:

The amount of JMSContexts and JMSConsumers is related to the concurrency annotation attribute, it is based on JMS 2.0.

The amount of Sessions and MessageConsumers is related to the concurrency annotation attribute, it is based on JMS 1.1.