Recurring events with timezone

Gunnar Wrobel wrobel at
Mon Oct 11 10:03:04 CEST 2010

Hi Hendrik,

Zitat von Hendrik Helwich <h.helwich at>:

> Am Sonntag, 10. Oktober 2010 21:59:37 schrieb Gunnar Wrobel:
>> [..]
>> I don't see a direct limitation there. The conversion to UTC is
>> certainly possible and valid while you are doing it to and from one
>> timezone. I see a problem once you are looking at the same event with
>> a client in a different timezone.
>> And to be honest I believe there are still some significant problems
>> when it comes to timezones on the Kolab server.
>> But maybe you can detail what the exact problem that you are having
>> with the conversion is.
> Hi Gunnar,
> ok i should have made an example:
> * person A has a client which stores events in iCalendar data (like  
> evolution)
> and creates a recurring event which occurs every Monday at 8:00 in the german
> time zone
> * person B has a kolab client like kontact and needs to attend this  
> event. The
> time of this event need to be converted to UTC format due to the kolab
> format. So in the kolab server the start time is stored with 6:00 UTC due to
> the german time zone difference of two hours from UTC time.
> * person B is also in the german time zone. The kolab client of person B will
> add 2 hours to the stored UTC time and the shown start time will be 8:00. So
> everything is fine till now
> * In germany at 31.10.2010 the difference of the local time to UTC changes
> form 2 to 1 hour due to the daylight saving time.
> * the shown start time of the event will be still 8:00 for person A but 7:00
> for person B because the kolab client will only add one hour to the stored
> UTC time 6:00.

This last point is something I don't understand. Both persons are  
still in the same time zone, are they not? If so why does the "kolab  
client" only add one hour then? And which client do you refer to  
exactly with "kolab client"? Kontact?

>> I could imagine that you might also be able to solve your specific
>> problem by adding a custom attribute to the event XML.
> It would be possible to preserve the time zone information of  
> calendar data by
> adding custom tags.
> Unfortunately this would not solve the problem because the time zone
> information would not be considered by a kolab client if time zone data is
> nor part of the kolab format.

Yes, I assume that we need to add this. But I didn't put any research  
into it at the moment. I would need to check what we already did in  
that area and what the problems might have been.

Bernhard, do you have a quick comment on this? If not I'll go search  
the issue tracker and our archives :)



> Greets,
> Hendrik
>> Cheers,
>> Gunnar
> _______________________________________________
> Kolab-format mailing list
> Kolab-format at

Gunnar Wrobel
Developer, Kolab Systems AG

e: wrobel at
t: +49 700 6245 0000

pgp: 9703 43BE

This message was sent using IMP, the Internet Messaging Program.

More information about the format mailing list