Re: [Evolution-hackers] cleaning up the timezone handling mess

["Suman Manjunath" <manjunath suman gmail com>]

On Wed, Apr 16, 2008 at 10:00 PM, Patrick Ohly <Patrick Ohly gmx de> wrote:
> On Wed, 2008-04-16 at 13:59 +0530, chenthill palanisamy wrote:
>  > > I don't get this part. Can you elaborate what you mean? Are you saying
>  > > that storing a VTIMEZONE with TZID=FOO as TZID=FOO 2 when it conflicts
>  > > with an existing VTIMEZONE should be avoided?
>  > yes, if  libical is modified to return VTIMEZONE with the history and
>  > once mapping between "foreign" timezones to system timezones is done at
>  > the backend, this is would not be required. All the older events would
>  > be properly displayed.
>
>  You assume that the mapping works in all cases. I don't think this is
>  realistic. There will always be a program FOO somewhere, somewhen using
>  a TZID=BAR which is unknown to Evolution and thus cannot be mapped. Even
>  getting this right just for Outlook alone will be challenging and
>  require permanent maintenance.

Very true.. it was/is a serious PITA while I was figuring out the
details for the MAPI provider.
On the brighter side, Exchange/Outlook 2007 has got this sorted out to
an extent. They now store the historical rules in the timezone blob.
See [1].
(The MAPI provider does not yet makes use of these rules, it only
identifies the timezone - maps it to one of the system timezones -
then uses the system timezone information to generate the start-end
times of the event.. its a todo on my list to make use of the stored
information :-) )

And, like you have mentioned, the mapping needs constant maintenance
despite publications like [2] or [3] :-(

-Suman

[1] http://blogs.msdn.com/stephen_griffin/archive/2006/12/06/outlook-2007-timezone-structures.aspx
[2] http://msdn2.microsoft.com/en-us/library/ms912053.aspx
[3] http://technet2.microsoft.com/WindowsVista/en/library/31f49a21-cfed-4b63-b420-58a9eabbb04e1033.mspx?mfr=true