Detect link state ?

[imp]

Dear all..

I have two hosap one is hostap master (my desktop) and the other is hostap station mode in my notebook.
actually I can link from notebook to desktop. and communicate well...

My question is, what parameter or information to detect that Is it linked or not between notebook 
and desktop in my notebook side ?, In addition too, How can I detect when my note book associate or disassociate 
with the desktop(AP) and  when my notebook reassociate the other desktop (If I have more hostap master) as roaming 
other AP in notebook side ?

Thanks for your comment and welcome to any advice...

Bernard