Re: [Tzdist] Fwd: [tzdist] #32 (service): managing historical data

[Lester Caine <[e-mail]>]

On 11/12/14 21:01, Cyrus Daboo wrote:
> Having everyone agree to use a reliable and timely tzdist service
> eliminates many (not all) of the big issues that exist today. Yes,
> clients will still need to be smarter about dealing with time zone
> changes when they occur - and that is what this debate needs to stay
> focussed on. What information does tzdist need to provide in the data it
> provides to ensure that clients have the necessary information to do
> more advanced reconciliation of events when a time zone change occurs.

I feel the case has been made for the ability to manage each published
version of a published data set? Using the version tagging. That a
server only needs to maintain versions for those TZid's which have
changed keeps the volume of data down. Probably 90% of data will never
change and so the very first version will still be used to provide that
material. Many updates will only be perhaps three or four TZid's and
potentially clients may never even read those as they are out of scope
for their calendars.

As new material is published using the current data, the correct version
can be tagged, so an archive can maintain a consistent view of it's
content. SO that only needs a server which is able to provide the
versioned views. As far as I am concerned, genealogical data needs this
facility and so has to use a server capable of it - with a backzoneTZ
base probably complimented by a historic location mapping database as well.

The problem is if event calendars published today need this versioning?
If they only contain data that is never likely to be part of a new
version, then obviously not, but it's what level of 'error' is
acceptable for material which is subsequently retained in archives and
used later in other cross references. That a meeting time is an hour
adrift may not matter so we can simply say 'tough' and ignore
discrepancies, but I'd still like a better explanation on how one
ensures that when a change in offsets are applied which invalidates
existing forthcoming events, this is notified without the use of a version?

-- 
Lester Caine - G8HFL
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