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Adrian Matei for Codever

Posted on • Edited on • Originally published at codever.dev

How to consume a text message from a JMS queue with a Message Driven Bean (MDB)

#java #jms #ejb #javaee

In the snippet you can see a message driven bean set up to consume asynchronously messages from a JMS queue:

import javax.ejb.ActivationConfigProperty; import javax.ejb.MessageDriven; import javax.ejb.MessageDrivenContext; import javax.ejb.TransactionAttribute; import javax.ejb.TransactionAttributeType; import javax.inject.Inject; import javax.jms.JMSException; import javax.jms.Message; import javax.jms.MessageListener; import javax.jms.TextMessage; import javax.xml.bind.JAXBException; import org.slf4j.Logger; import org.slf4j.LoggerFactory; @MessageDriven( name = "AccountMessageBean", activationConfig = { @ActivationConfigProperty( propertyName = "destinationType", propertyValue = "javax.jms.Queue"), @ActivationConfigProperty( propertyName = "destination", propertyValue = "java:jboss/exported/queue/account.queue"), @ActivationConfigProperty( propertyName = "acknowledgeMode", propertyValue = "Auto-acknowledge") }) public class AccountMessageBean implements MessageListener { private static final Logger logger = LoggerFactory.getLogger(AccountMessageBean.class); @Inject MessageDrivenContext messageDrivenContext; @Inject MessageService messageService; @Override @TransactionAttribute(TransactionAttributeType.REQUIRED) public void onMessage(Message message) { if (!(message instanceof TextMessage)) { logger.warn("This is not a text message. Break"); return; } TextMessage messageText = (TextMessage) message; try { if (messageText.getText().contains("organisation")) { this.messageService.createOrganisation(messageText.getText()); } else if (messageText.getText().contains("person")) this.messageService.createPerson(messageText.getText()); else { logger.warn("Something went wrong, must be one of those types"); } } catch (JMSException | JAXBException e) { logger.error("An error occured while processing the message, mark to rollback"); messageDrivenContext.setRollbackOnly(); } } }
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Note the following:

  • @MessageDriven annotation where the type of the consumed resource is defined (destinationType - here javax.jms.Queue, but it could also be javax.jms.Topic), the location of the queue (propertyName = "destination") and that the message from the queue is acknowledged once the processing is successful (this is the default setup)
  • the consuming message driven bean implements the javax.jms.MessageListener and the method onMessage(Message message)
  • if a container-managed transaction is not present a new one is created - @TransactionAttribute(TransactionAttributeType.REQUIRED)
  • the consumed message is expected to be text (javax.jms.TextMessage)
  • you access the string value of the message by calling the getText() method - messageText.getText()
  • MessageDrivenContext is used to gain additional access to transaction management - here the transaction is marked for rollback, if an error occurs messageDrivenContext.setRollbackOnly(); (this is only possible in container-based transactions)


Reference -

https://docs.oracle.com/javaee/6/tutorial/doc/bncgl.html#bncgq

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