code: protected void connectToJMS(String clientId) throws MessagingException {
          // Check to see if already connected
          //
          if (connected == true) return;
  
          try {
              // Get a JMS Connection
              //
              connection = getConnection();
              if(clientId != null) {
                  connection.setClientID(clientId);
              }
              connection.start();
              connected = true;
              logger.debug("connectToJMS - connected");
          } catch (JMSException e) {
              connected = false;
              logger.error("JMSManager.connectToJMS - Exception occurred:");
              throw new MessagingException(e.getMessage(), e);
          }
      }
docs: Internal worker methods