Re: [Tzdist] Existing and new data ...

[Cyrus Daboo <[e-mail]>]

Hi Lester,

--On December 10, 2014 at 5:43:30 PM +0000 Lester Caine 
<[e-mail]> wrote:

> We are talking about a very narrow group of TZid's and very infrequent
> events, but race conditions like these can't simply be brushed under the
> carpet. Even today upcoming TZ data changes are being discussed and
> these may well effect a diary of event published for next year. SInce
> changedsince only has relevance once one HAS downloaded the data it
> can't be used to sync with other published material, only version can
> provide the safety of ensuring that the correct information and TZ data
> are used ... even if that THEN flags that events may be incorrect due to
> 'latest' being a later version ... perhaps three or four versions ahead
> for a half yearly diary.

I have not come across a single client to date that will detect a change to 
time zone data and warn users about possible shifts to meeting times as a 
result of that. They simply can't figure that out as the underlying TZ data 
typically is coming from the OS and there is no version information readily 
available.

With tzdist, we have the option of including an extension for use with 
changedsince, whereby the server could tell the client exactly which time 
periods are impacted by a change to time zone data. But there is no point 
in implementing that in the base unless we know for sure clients will 
really use it. The first step here is to simply get them using the base 
protocol which should dramatically improve on the current state of affairs. 
Once we have that, more complicated pieces such as period change reporting, 
lookup via geo co-ordinates etc can be added.

-- 
Cyrus Daboo