online status with pjl

[Sterck Serge]

I need to known the exact status (out of paper,tray missing etc..)of printer placed in a kiosk in real time.

I have downloaded the hp backend and i saw
that they use pjl to enable unsolicited status of device and job
@PJL USTATUS DEVICE = ON \r\n at PJL USTATUS JOB = ON \
they start a thread that read this status and report this information back
to cups.

if i writen a new backend based on the usb backend must i use libusb or the traditionnal method to find the device looking at /dev/usb ?

The status of the printer is reported in cups only during the print of a job . Is there a possibility to report this in real time.