Re: [Evolution-hackers] [evolution-kolab] Datastructures for calendar data

[Hendrik Helwich <h helwich tarent de>]

Am Freitag, 1. Oktober 2010 08:51:44 schrieb Milan Crha:
> On Wed, 2010-09-29 at 17:15 +0200, Hendrik Helwich wrote:
> > So one option for us is to operate on the icalcomponent instead of
> > ECalComponent.
>
> 	Hi,
> internally yes, but remember, the ECalBackend API uses ECalComponent in
> most cases.

ok. we are not sure about this and will discuss it.

> > In our project we do not need any time zone information which is attached
> > to time data. It would be sufficient if all time data is stored in UTC
> > format. Then we could stay with the ECalComponent class.
> > Is there an easy way in evolution to strip timezone information from an
> > ECalComponent by converting local time data to UTC time data?
>
> Well, timezone information is crucial for users, usually, and you might
> not change they will to use always UTC. You know, when you are adding a
> new appointment into a calendar, then you can choose your own timezone
> (View->Timezone), also a different one from that used in Evolution
> (which is used as a default timezone).
>
> Imagine a user, a businessman, whom is living in US and cooperates with
> a Europe partner on regular bases. Say they have a phone meeting twice a
> month, which is held in Europe in some certain time. So our businessman
> living in America/New_York will enter his meeting in Europe/Berlin, and
> he'll see this in his timezone (because he has it set in Evolution),
> even though the internal ECalComponent timezone is Europe/Berlin. What
> is it good for? I believe you know. It's good because changes from
> summer to winter time and vice versa are done in different weeks in
> these timezones, and because the organizer is in Europe, then the New
> York time will be shifted accordingly based on Europe time in these
> periods, so our business man will not miss his meeting. If you would
> change timezones for all your components to UTC then the times may be
> wrong.

I understand this point for recurring events. In the Kolab format it is only 
allowed to store time data in UTC format (see 1.2.1 in [1]). So we have to 
think how we can handle this problem in our software.

> The other thing is that whenever there is recognized an event in
> different than Evolution user's timezone, Evolution is showing an icon
> about it on the event.
>
> Nonetheless, to answer your question, I didn't find an ECalComponent
> function for converting times between timezones, though I didn't search
> heavily, but there is used a libical function icaltimezone_convert_time
> for it.

ok. i will check this operation. Thank you!

Greetings,
Hendrik


[1] http://kolab.org/doc/kolabformat-2.0rc7-html/x123.html#AEN143


> 	Hope that helps,
> 	Milan