public void handle (ControlTask aControlTask) {
    logger.debug("received control task: {}", aControlTask);
    if(ControlTask.TYPE_CANCEL.equals(aControlTask.getType())) {
      String jobId = aControlTask.getRequiredString("jobId");
      for(TaskExecutionFuture<?> tef : taskExecutions.values()) {
        if(tef.taskExecution.getJobId().equals(jobId)) {
          logger.info("Cancelling task {}->{}",jobId,tef.taskExecution.getId());
          tef.cancel(true);
        }
      }
    }
  }
Handle control tasks. Control tasks are used by the Coordinator
to control Worker instances. For example to stop an ongoing task
or to adjust something on a worker outside the context of a job.
src/main/java/com/creactiviti/piper/core/Worker.java