@Daemon
public class MyTask implements Callable<Void> {
  @Context
  private ExecutionContext execution;
  private double fractionDone = 0.0;
  
  @Init
  public void preValidate() throws RejectedExecutionException {
    // any initialisation and/or error checking that needs to be
    // done when a call is made to TaskExecutor.start() or
    // TaskExecutor.execute().
  }
  
  @BeforeCall
  public void prepare() {
    // anything to do prior to call() being executed.
    // Typically defined within super-classes.
  }

  @AfterCall
  public void cleanup() {
    // anything to do after call() being executed.
    // Typically defined within super-classes.
  }
  
  public Void call() throws Exception {
    while (!execution.isCancellationRequested(true)) {
      // do stuff
    }
    return null;
  }

  @OnCancel
  public void cancelled(boolean mayInterruptIfRunning) {
    // anything special that needs to be done immediately,
    // such as calling Object.notify() on something
  }

  @OnPauseStateChanged
  public void pauseStateChanged() {
    if (execution.isPauseRequested()) {
      // anything that needs to be done as it is paused
    }
    else {
      // anything that needs to be done as it is resumed
    }
  }
  
  @Progress
  public ProgressState getProgress() {
    return new ProgressState() {
      public Double getFractionDone() {
        return fractionDone;
      }
    };
  }
}