Subject: [Ietf-calsify] Issue 27: Section 4.8.5.4 Recurrence Rule: Duration of members of the,generated recurrence set

From: bernard.desruisseaux at oracle.com (Bernard Desruisseaux)
Date: Thu Oct 19 10:52:11 2006

In section 4.8.5.4 Recurrence Rule it says:

 > Any duration associated with the iCalendar object applies to all
 > members of the generated recurrence set.

I believe we need to clarify what is meant by "duration" here.

Example 1:

   DTSTART;TZID=America/Montreal:20070311T000000
   DURATION:P1D
   RRULE:FREQ=DAILY;COUNT=2

   The first instance start at midnight on March 11th, 2007 and has
   a duration of 1 day. Given that on that day there is a shift from
   standard time to daylight saving time, this instance will actually
   last 23 hours.

   Should the duration of the recurrence instance that will occur on
   March 12th, 2007 be the "computed duration of the first instance",
   that is, 23 hours, or the "specified duration of the first instance",
   that is, 1 day?

   In my opinion, the duration of the recurrence instance on March 12th,
   2006 should be 1 day (24 hours).

Example 2:

   DTSTART;TZID=America/Montreal:20070311T000000
   DTEND;TZID=America/Montreal:20070312T000000
   RRULE:FREQ=DAILY;COUNT=2

   The first instance start at midnight on March 11th, 2007 and is
   specified to end at midnight on March 12th, 2007. Given that on
   that day there is shift from standard time to daylight saving time,
   this instance will actually last 23 hours.

   I believe the duration of the recurrence instance on March 12th,
   2006 should be the "computed duration of the first instance",
   that is, 23 hours.

All that being said:

   - I doubt that all (most?) iCalendar application will interpret
     P1D as 23 hours or 25 hours when a time zone shift occurs.

   - There are known iCalendar applications that don't even support
     the DURATION property today!

Cheers,
Bernard

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From: reinhold at kainhofer.com (Reinhold Kainhofer)
Date: Thu Oct 19 13:11:36 2006

>    DTSTART;TZID=America/Montreal:20070311T000000
[...]
>    2006 should be 1 day (24 hours).

I would also tend to say that if a duration is explicitly given, this duration 
applies to all recurrences. I would also tend to agree with you on your 
second example, where the duration is implicitly given as the difference 
between DTSTART and DTEND.

>      P1D as 23 hours or 25 hours when a time zone shift occurs.

How many applications really take into account that extra or missing hour in 
the GUI?

Cheers,
Reinhold

PS: This would also be a nice example in a iCalendar test suite... Is there 
any "official" place where we can install an FAQ (as suggested in my previous 
mails) or such a test cases repository?
- -- 
- ------------------------------------------------------------------
Reinhold Kainhofer, Vienna University of Technology, Austria
email: [email-masked], http://reinhold.kainhofer.com/
 * Financial and Actuarial Mathematics, TU Wien, http://www.fam.tuwien.ac.at/
 * K Desktop Environment, http://www.kde.org, KOrganizer maintainer
 * Chorvereinigung "Jung-Wien", http://www.jung-wien.at/

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From: lists at block-online.eu (Oliver Block)
Date: Thu Oct 19 13:59:57 2006

Am Donnerstag, 19. Oktober 2006 22:11 schrieb Reinhold Kainhofer:
> PS: This would also be a nice example in a iCalendar test suite... 

I agree.

> Is there 
> any "official" place where we can install an FAQ (as suggested in my
> previous mails) or such a test cases repository?

How about 

http://tools.ietf.org/wg/calsify/

Regards,

Oliver

---

From: lists at block-online.eu (Oliver Block)
Date: Thu Oct 19 14:02:15 2006

I agree.

>    2006 should be the "computed duration of the first instance",

hm...

Ragards,

Oliver

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From: aki.niemi at nokia.com (Aki Niemi)
Date: Wed Oct 25 16:02:41 2006

> http://tools.ietf.org/wg/calsify/

Not sure if that's an appropriate place.

However, in other working groups similar types of test cases have been
published as an informational RFC. See for example RFC 4475. I know it
has been very useful as a primer to people attending the interop events.

If the working group thinks something like this would be useful and
someone is willing to write the I-D, I think we could consider it.

Cheers,
Aki

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From: Dave.Thewlis at calconnect.org (Dave Thewlis)
Date: Wed Oct 25 17:54:00 2006

As it happens, CalConnect has also published a number of test cases and 
test streams on its website and would be delighted to host a FAQ and/or 
test cases.  The more the better.

Cheers,

Dave Thewlis
-- 
*Dave Thewlis, Executive Director
Calconnect - The Calendaring and Scheduling Consortium*
+1 707 840 9391 (voice) ? +1 707 498 2238 (mobile)
http://www.calconnect.org ? [email-masked] 
<mailto:[email-masked]>

Aki Niemi wrote:
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From: sroberts at uniserve.com (Sam Roberts)
Date: Thu Oct 26 08:29:00 2006

> has been very useful as a primer to people attending the interop events.

The S/MIME group publishes a growing set of test-data. Its incredibly
useful. It also contains some nice perl code to rip it apart into the
test suite.

I don't think recurrence rules would have been implementable by many
without the examples.

More examples that demonstrate corner cases and illustrate the answers
to the questions raised on this group would be particularly useful.

Its a lot of work but it sure would be nice...

Sam