To implement a periodic execution of Tasks you have currently to manually restart a service with registering a listener:

Service<...> service;

 service.stateProperty().addListener(new ChangeListener<Worker.State>() {
            public void changed(ObservableValue<? extends Worker.State> observable, Worker.State oldState, Worker.State newState) {
                if (newState.equals(Worker.State.SUCCEEDED) || newState.equals(Worker.State.FAILED)) {
                    service.reset();
                    service.start();
                }
            }

        });


An out-of-the-box support for polling in javafx.concurrent.Service is appreciated: long-pooling of RESTful services is a common practice for the implementation of server push.