In ours warehouses, all mobile devices are mounted on forklift.
On each forklift is mounted a wireless labels printer also.
In our warehouses we work by work shifts, so different warehouse worker operates (open work sessions with different user ID) on the same mobile device in a day.
So, regardless the warehouse worker user ID, we need to know the device (IP, Client ID, whatever information that identify the device) to send the printed labels to the printer associated to the device.
In Mobile device XML warehouse user session is only possible to know the user but not the device.