Freebusy with workingHours

[dursti96]

Hi,

at the moment I am working on a webapp which can display/create Zimbra events with CalDAV.
I am using Python/Django + the python caldav package pypi.org/project/caldav/

Now i need to implement displaying FreeBusy of attendees when an event is created (with working hours, which are set in user settings).
The FreeBusy information i currently plan to get with zimbra-server.example/home/user/?fmt=ifb, but this does not contain the users working hours.

I saw that the Soap api can be used (getWorkingHours), but i couldn't figure out how to use the api.

Is there an easier method to get the working hours of different users? Or even better, to get FreeBusy which already contains working hours?
My goal is to implement a graphic which displays freebusy times for each attendee, like its done in the Zimbra web app.

Thanks,
Alex