[tz] Support for the IANA database in the Python standard library

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Wed Feb 26 22:40:01 UTC 2020

On 2020-02-26 14:31, Paul Eggert wrote:
> On 2/25/20 6:40 PM, Paul Ganssle wrote:
>> My main concern is that my hope is to try to use a time zone data source that
>> can be managed at the system level, independent of language stack. I will
>> admit to never having looked into the details, but I was under the impression
>> that tzdist was something that the system would consume, rather than
>> individual programs, is that wrong?
> As a protocol, tzdist can be used both by individual programs and by the system.
> It's still pretty new and I don't know of any census, but at least Cyrus
> supports it so that clients can have the latest tzdata even if their OS tzdata
> is out-of date; see
> <https://www.cyrusimap.org/imap/download/installation/http/caldav.html>.

Reading that, Cyrus supports converting tz data sources to iCalendar data with
vzic which it then makes available via CalDAV for calendar clients; it does not
appear to support zoneinfo binary data or TzDist for tzdata clients:
"This module is designed to use the IANA Time Zone Database data (a.k.a. Olson
Database) converted to the iCalendar format.
Cyrus uses a modified vzic to convert IANA formatted data into iCalendar format."
and predates TzDist:
"recently downloaded time zone data (e.g. “IANA Time Zone Database v.2013h”)"

The CMU server no longer appears to be available.

> Absolutely. All I'm saying is that the proposal should not preclude having the
> implementation use tzdist rather than TZif files in the OS. One can use tzdist
> to distribute TZif data, after all.

Allow your proposal backend to work with local or remote files or tzdist server.

Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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