[horde] Can't add Outlook meeting request to Kronolith

Michael J Rubinsky mrubinsk at horde.org
Thu Jan 10 00:31:54 UTC 2013

Quoting Michael M Slusarz <slusarz at horde.org>:

> Quoting Michael J Rubinsky <mrubinsk at horde.org>:
>> Quoting Michael M Slusarz <slusarz at horde.org>:
>>> 1) The code is released under GPL.  However, the two most logical  
>>> places to put something like this (Horde and/or a framework  
>>> library) are released under LGPL.  So we'd have to do some  
>>> annoying packaging tricks to work around this.
> [snip]
>> Since the RFC does not specify that the TZID need to conform to any  
>> standard, nor does it state that the timezone rules specified need  
>> to actually match an existing valid OLSEN/TZDB timezone (which is  
>> the cause of this problem to begin with), we can't simply convert  
>> the provided timezone rules/offsets into a known TZID - we would  
>> have to store the entire VTIMEZONE component with the event data  
>> then EVERY time we need the event's time we would need to use the  
>> VTIMEZONE to run an algorithm to determine the current time we  
>> want. This would be a nightmare. So, option (2) is not desirable.
>> Option (1) would be the least objectionable solution if we can work  
>> around the license issues.
> Option (1) is even more worthless though, since TZID can be ANY  
> string - there is no guarantee the text corresponds to any known  
> timezone identifier.  So trying to do a Timezone -> TZDB translation  
> *solely* on the TZID string is absolutely NOT the correct solution.   
> At best, it is a terrible lazy hack.
> It may be a "nightmare", but the only 2 viable and correct options  
> appear to be:
> 1) Storing the timezone information with the event.

Not acceptable. See previous reply.

> 2) Mapping a timezone string -> Olsen/TZDB string based on the  
> timezone offsets contained within the VTIMEZONE.

This is doable, but not foolproof. It's similar to what I do in  
ActiveSync's timezone support. I would suggest a combination of the two:

Create a mapping as described in (1). Attempt to sniff out the correct  
timezone based on offsets/transitions using the mapped OLSEN name as a  
preferred result in the case of non-unique results. See  
Horde_ActiveSync_Timezone for more information.


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