How to implement multiple applications to consume from the same topic at the same time? - jms

Question

I have the following applications:
Publisher Server --> Publish {name} to topic name
Consumer Server A --> Consumes topic name, prints "Hello, " + name
Consumer Server B --> Consumes topic name, prints "Good bye, " + name
I'm using Spring Boot 2.7 with Spring JMS and ActiveMQ.
The expected result:
For each name published, both consumer servers consume the data, so the expected result for each published message should be (IE publish name John and then Jane):
Hello, John
Good bye, John
Hello, Jane
Good bye, Jane
The actual result:
Hello, John
Good bye, Jane
Meaning, the two consumers are alternating to consume from the topic.
The code:
Each server has the same application.yml configuration to connect with ActiveMQ server.
Publisher Server - publisher code:
#RequiredArgsConstructor
#Component
public class Publisher {
private final JmsTemplate jmsTemplate;
public void publish(final String name) {
jmsTemplate.convertAndSend("name-topic", name);
}
}
Consumer Server A - Subscriber code
#RequiredArgsConstructor
#Component
public class SubscriberA {
#JmsListener(destination = "name-topic")
void welcome(final String name) {
System.out.println("Hello, " + name);
}
}
Consumer ServerB - Subscriber code
#RequiredArgsConstructor
#Component
public class SubscriberB {
#JmsListener(destination = "name-topic")
void welcome(final String name) {
System.out.println("Good bye, " + name);
}
}
I tried to use the different properties of the #JmsListener like the concurrency property, with no luck.

Answer 1

I found the solution.
By default, Spring JMS configuration is set to work with Queues instead of Topics.
Creating the necessary configuration beans and setting the .setPubSubDomain(true); fixed the problem.
Changes I needed to implement:
Add JMS configuration:
#RequiredArgsConstructor
#Configuration
#EnableJms
public class JmsConfiguration {
private final ConnectionFactory connectionFactory;
#Bean
public JmsTemplate jmsTemplate() {
// To publish messages as topics, setPubSubDomain to true
final JmsTemplate jmsTemplate = new JmsTemplate();
jmsTemplate.setPubSubDomain(true);
jmsTemplate.setConnectionFactory(connectionFactory);
return jmsTemplate;
}
#Bean
public DefaultJmsListenerContainerFactory defaultJmsListenerContainerFactory() {
// To subscribe to topics instead of queues, setPubSubDomain to true
final DefaultJmsListenerContainerFactory defaultJmsListenerContainerFactory = new DefaultJmsListenerContainerFactory();
defaultJmsListenerContainerFactory.setConnectionFactory(connectionFactory);
defaultJmsListenerContainerFactory.setSessionTransacted(true);
defaultJmsListenerContainerFactory.setPubSubDomain(true);
return defaultJmsListenerContainerFactory;
}
}
Change the #JmsListener(s), adding the created ContainerFactory
#RequiredArgsConstructor
#Component
public class SubscriberA {
#JmsListener(destination = "name-topic", containerFactory = "defaultJmsListenerContainerFactory")
void welcome(final String name) {
System.out.println("Hello, " + name);
}
}
#RequiredArgsConstructor
#Component
public class SubscriberB {
#JmsListener(destination = "name-topic", containerFactory = "defaultJmsListenerContainerFactory")
void welcome(final String name) {
System.out.println("Good bye, " + name);
}
}