Update UI in intermediate step

If I understood it correctly the Vaadin request/response works in following steps

  1. Ajax request comes from the browser
  2. In the server we process the request, changes are made in Vaadin components etc
  3. Ajax response is sent to the browser, and UI get updated

So until the 2nd step is complete the UI is not updated.

What I need to do is, after request comes to my Vaadin page I need to perform lets say 3 steps, and I want the UI to be updated after I complete Step 1, and then I process Step 2 & 3, and then the UI gets updated again.

Is there any way to achieve this. I want a way to force the browser to be updated.

You need to use a background thread and some polling (ProgressIndicator or Refresher add-on) or push (various add-ons, will be integrated in Vaadin 7.1) solution to achieve this.

this thread
for more information on push, locking etc.