public void activate() throws Exception {
      Output<TransactionApplicationEvents, ApplicationEventReplayException> playerOutput =
          ApplicationEvents.playEvents(player, receiveEmails);

      tracker =
          new ApplicationTransactionTracker<ApplicationEventReplayException>(
              stream, eventSource, config, playerOutput);
      tracker.start();
    }
 public void passivate() throws Exception {
   tracker.stop();
 }