I'm starting with ExtJS so my question may very well already been answered somewhere in these forums, but I couldn't find it. I want to start a web app to show some stock prices on some grid. The catch is, the stock prices will change (in the end, in realtime) and when the server knows that a price has changed, it needs to send that change to the client (no polling every X seconds from the client side). So, the server needs to invalidate the store the client is using, somehow. And the client needs to know exactly what price has changed, so that it can change the background color of that cell for a brief period of time. How do you start this? I'm quite certain this can easily be done in ExtJS, but I'm not really sure how.