Looks like there is a race condition when handling multiple CASes coming in at the same time from the same client. The first thread creates a Connection and sets up a Session then the second thread sees the Connection made and proceeds to send a reply. The Connection has not yet started though, resulting in
20 Jan 2014 14:32:18,426 WARN DUCC.ActiveMQSessionExecutor - Received a message on a connection which is not yet started. Have you forgotten to call Connection.start()? Connection: ActiveMQConnection
Start the Connection as soon as it is created in a synchronized block.