How to signal smart card activity at the PC/SC level? Using D-Bus? HAL?

[Ludovic Rousseau]

Hello,

I am the maintainer of pcsc-lite [1] a middleware to access smart
cards and smart cards readers.
I am really new to D-Bus and HAL.

Someone asked for an applet that would indicate if a card activity is
ongoing or not. The idea is to have the equivalent of a smart card
reader blinking LED but in a gnome applet. The idea is nice. Some of
my readers do not blink the LED when an APDU is exchanged so it is not
easy to know if something is happening. In general I look at the pcscd
debug logs but a Gnome applet would be nicer/more integrated.

My question is: what mechanism to use to convey the information?
I was thinking of using D-Bus and also provide other information like
reader insertion/removal, card insertion/removal. And then card
communication status.

I need a one-way only event mechanism to signal events. Maybe D-Bus is
too complex and HAL is the correct answer to my problem?

Is D-Bus a good enough mechanism for that? Or should I use something
else? Is HAL more appropriate?
Any comment on this idea?

This may be related to the smart_card_reader HAL name space proposed
(and accepted) in [2].

Thanks,

[1] http://pcsclite.alioth.debian.org/
[2] http://bugs.freedesktop.org/show_bug.cgi?id=19663

-- 
 Dr. Ludovic Rousseau