[horde] Timeshift on ActiveSync to Horde

[Michael J Rubinsky]

Quoting Stephan Kleber <stephan at admin.nabira.de>:

> Zitat von Michael J Rubinsky <mrubinsk at horde.org>:
>> That depends. If you don't use UTC then all events in Kronolith are  
>> in a "floating" timezone. That is, they are always assumed to be in  
>> the user's current timezone. This is fine if you never cross  
>> timezones or do not have to schedule meetings with people in more  
>> than one timezone, or have recurring events that span DST switches  
>> etc... If you want to really support timezones, you need to use UTC.
>>
>> So, if the user's device is in a different timezone than their  
>> Horde prefs indicate, this could very well be the source of your  
>> issue.
>
> Until now I had no issues with timezones. All my users are in one TZ  
> and none has ever asked about it or reported problems. I see the  
> benefits of using UTC based storage, but if conversion is not  
> mandatory, it should work this way either.
>
> I will convert the database all the while. Perhaps it helps,  
> although I would not have the necessity to do it otherwise.
>
> Stephan


I have not forgotten about this. In debugging *this* issue, I  
discovered another, more important issue that caused a 1 hour  
timeshift from server -> client for recurring events that span a DST  
transition (as opposed to your reported issue of client -> server).  
The fix for *this* issue is included in the latest round of releases  
that dropped today (including the ActiveSync and Date package) and had  
to due with a bug parsing a date object on the exact hour of a DST  
transition.

The issue you are reporting is due, I believe, to the fact that we  
seem to be currently ignoring the timezone data structure that is sent  
from the device. Part of the problem is that all of the devices I've  
tested only send transition dates and offsets - and omit the timezone  
identifier (this is allowed by the spec) - so we are going to need to  
either parse these values into a timezone identifier, or otherwise  
adjust the UTC time. This should only affected recurring events that  
are created or edited on the device that span a DST transition.

It is most likely a coincidence that you noticed this after a recent  
upgrade - it is more likely the recent switch from daylight to  
standard time is what has brought this to your users' attention.


-- 
mike

The Horde Project (www.horde.org)
mrubinsk at horde.org