interface ihello {
  in void hello();
  in void cancel();
  out void world();
  behaviour {
    bool triggered = false;

    [!triggered] on hello: triggered = true;
    [triggered]  on hello: illegal;

    [triggered] on cancel: triggered = false;
    [!triggered] on cancel: illegal;

    [triggered] on inevitable: {triggered = false; world;}
  }
}

interface iworld {
  in void hello();
  in void cancel();
  out void world();
  out void canceled();
  behaviour {
    bool triggered = false;
    [!triggered] on hello: triggered = true;
    [triggered] on hello: illegal;

    on cancel: {triggered = false; canceled;}

    [triggered] on inevitable: {triggered = false; world;}
  }
}

component hello_blocked_external {
  provides ihello h;
  requires external iworld w;

  behaviour {
    bool triggered = false;
    [!triggered] on h.hello(): {
      w.hello();
      triggered = true;
    }
    [triggered] on h.cancel(): blocking {
      triggered = false;
      w.cancel();
    }
    on w.canceled(): {
      h.reply();
    }
    [triggered] on w.world(): {
      triggered = false;
      h.world();
    }
    [!triggered] on w.world(): {
    }
  }
}