Extracting information from a webservice

Dirk Hohndel dirk at hohndel.org
Wed Jan 23 12:55:11 PST 2013

"Robert C. Helling" <helling at atdotde.de> writes:
>> We do NOT want timezone. The reason is that dive computers tend to
>> ignore time zone as well. So we don't want to correct for time zone at
>> all - just local time!
>> So from where I sit the current date/time setup works just fine (see the
>> POC patch I just sent)
> are you sure about this? Which local time? Local time of the dive site
> (which is what I would have liked displayed) or local time of the
> computer that runs subsurface which might be different if I connect my
> dive computer only after I go home. And even when I am traveling, I
> hardly ever adjust the time zone of my laptop to reflect where I am.

That's a really bad habit. But unless you have one of the weird data
tracking devices that don't actually have a builtin clock you are
getting local time as the divecomputer saw it. And that should be the
correct data as I sure hope you do set your divecomputer time to be
correct. If not you can always fix it in Subsurface...

> I don't know about many dive computers but the ones where I looked at
> the protocol all just reported the time difference between the time of
> the dive and the time of the read out. My Suuntos display time like a
> watch as well but usually I do not bother to set DST as I don't use
> them as a watch.

The you are in trouble. The Suuntos report "time" to us - without a
timezone, just a time. And that's what we record. Local time.

> I don't know how this gets sorted out but my approach would be to
> either do keep track of time zones (and the local ones of the dive
> might be inferred from gps data if existent) or universally use a
> standard time zone like UST or epoch and convert only for display.

We do neither of those two. We always use 'local time'. Saves us a LOT
of headaches. And removes a ton of ways in which dive computers break
timezone handling. The Uemis SDA, for example, gets time zones
completely wrong. It claims to store UTC plus an offset, but actually
stores local time (plus the offset - which is now in the wrong
direction). Many other computers store no time zone information at


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