guide jms

Table of Contents

• Messaging
  • Products
  • Receiver
    • JMS Listener
  • Sender

Messaging

Messaging in Java is done using the JMS standard from JEE.

Products

For messaging you need to choose a JMS provider such as:

• RabbitMQ

• ActiveMQ

• Oracle Advanced Queuing (esp. if you already use Oracle RDBMS)

Receiver

As a receiver of messages is receiving data from other systems it is located in the service-layer.

JMS Listener

A JmsListener is a class listening and consuming JMS messages. It should carry the suffix JmsListener and implement the MessageListener interface or have its listener method annotated with @JmsListener. This is illustrated by the following example:

@Named
@Transactional
public class BookingJmsListener /* implements MessageListener */ {

  @Inject
  private Bookingmanagement bookingmanagement;

  @Inject
  private MessageConverter messageConverter;

  @JmsListener(destination = "BOOKING_QUEUE", containerFactory = "jmsListenerContainerFactory")
  public void onMessage(Message message) {
    try {
      BookingTo bookingTo = (BookingTo) this.messageConverter.fromMessage(message);
      this.bookingmanagement.importBooking(bookingTo);
    } catch (MessageConversionException | JMSException e) {
      throw new InvalidMessageException(message);
    }
  }
}

Sender

The sending of JMS messages is considered as any other sending of data like kafka messages or RPC calls via REST using service-client, gRPC, etc. This will typically happen directly from a use-case in the logic-layer. However, the technical complexity of the communication and protocols itself shall be hidden from the use-case and not be part of the logic layer. With spring we can simply use JmsTemplate to do that.