[Click] event notification in click

[Vladimir Bychkovsky]

Hi,

I would like to use Click to do automatic WiFi measurements (on
embedded computers in cars). Click already has a lot of separate
modules handling individual stages of the experiments ( 802.11 beacon
collection, association, etc ).

My current plan is to implement a controller (as a separate element)
to drive the experiment. However, such controller would need to
receive notification messages from other elements. For example, it
would need to be notified when authentication response is received.

Ideally, I would like to use an existing notification system. I think
some publish/subscribe scheme would work very well in my case.

The only alternative that I could think of is using ClickChatter to
notify an external controller process and using element handlers for
control. However, I am afraid of this being too slow. One of the goals
of this measurement system is to have low overhead. That is why I
thinking about implementing the controller inside Click.

So, my questions are:
1) Are there any reasons why I should avoid creating a controller as
an element in click? (I.e. is this a bad idea?)
2) Are there any event notification schemes for click out there?
( I only found was a NotifierQueue element, but that not exactly what
I was looking for, since it is designed for data packets... )
3) Is it a bad style to use specially formatted Packets for control
notification?

I am new to Click, so, any pointers/suggestions/correction are welcome.

Thanks in advance,
Vlad.