Real time viewing of geometry data from a source file

Hi, I have what I think is a simple question. I have a simple shape, call it a Quad. The points of the Quad are initially read from a file, in this case an excel workbook. What I want is to be able to update the points in excel and have my vtkRenderWindow update in real time. Can someone point me in the right direction?

Apologies if this topic already exists but i have not found it.