In the B2B example, we are using the JMSCorrelationID as a way for the Retailer to associate its identity with its reply message, as illustrated by the following code in Retailer.autoBuy( ) :

private void autoBuy (javax.jms.Message message){
    ...
    publisher = session.createPublisher(buytopic);
    textMsg.setJMSCorrelationID("DurableRetailer");
                
    publisher.publish(
           textMsg,
           javax.jms.DeliveryMode.PERSISTENT,
           javax.jms.Message.DEFAULT_PRIORITY,
           1800000);
        ...           
}

In Wholesaler, the JMSCorrelationID is extracted in the onMessage( ) handler, and simply printed on the command line:

public void onMessage( javax.jms.Message message){
        ...           
         System.out.println("Order received - "+text+
                            " from " + message.getJMSCorrelationID( ));
        ...           
   }

Another way to associate the Retailer's identity with the reply message would be to store something unique in a message property, or in the message body itself.

A more common use of the JMSCorrelationID is not for the sake of establishing identity; it is for correlating the asynchronous reception of a message with a message that had been previously sent. A message consumer wishing to create a message to be used as a response may place the JMSMessageID of the original message in the JMSCorrelationID of the response message.