WDM - Client Checkin at regular intervals

Dear all ,

I am new to using WDM for managing Thin Clients . The documentation mentions several times
"client checkin " to WDM with client information like Serial No, Type and other device related information .
I am not sure what does "checkin" means here from a protocol perspective ? Is this HTTP ? SNMP ?
Wyse Proprietarty protocol ?

Alternatively , if someone has wireshark network traces that would help in figuring out this basics ?

Yours truly ,