Asynchronously update vaadin components

Question

I have this code for updating vaadin button's caption every 3 seconds.

TimerTask tt = new TimerTask() {

    @Override
    public void run() {
        try {
            logger.debug("adding l to button's caption");
            btn.setCaption(eventsButton.getCaption() + "l");
        } catch (Exception ex) {
            logger.error(ex.getMessage());
        }
    }
};
Timer t = new Timer(true);
t.scheduleAtFixedRate(tt, 0, 3000);

However, it can't change button's caption although it is executed every 3 seconds(judging by the log file). How can I access vaadin's GUI components from another thread?

Solution 1

There's an addon named ICEPush which does exactly what I needed.

https://vaadin.com/directory#addon/icepush

Solution 2

A reasonably comprehensive discussion of the problem, and the various solutions can be found here; Redux: 'vanilla' Vaadin simply follows a user initiated request-response paradigm.

You'll need to use an add-on to initiate changes in the browser from the server.

Aside : you should synchronize on the application object when updating components from your own threads (as opposed to the normal request thread) - as you may get 'Sync' errors.