[Kde-pim] Recurring entries in Calendars, with exceptions

[Shaheed Haque]

Hi Christian, Georg,

So after a bit of bashing on openchange [1], I managed to get exceptions
out of Exchange, and can now feed them into KOrganizer via Akonadi. The use
of the recurrenceId works as you suggested it should - that's the good
news. The interesting thing is what somebody (I presume KOrganizer) does
with the other properties on the displayed exception Item:

1. It takes a subset of the properties from the exception item (subject,
location, times AFAICS)

2. It seems to take another subset of its properties from the "parent"
recurring event (description, AFAICS)

3. It ignores other properties completely (e.g. the Alarm, attendees)
whether they are set on the exception or the parent.

So, it sounds like the basic plumbing for both information routes 1 and 2
is in place. So, perhaps it is just a question of tracking down route 1,
and fleshing it out a bit?

Thanks, Shaheed

[1] See http://tracker.openchange.org/issues/391

On 19 March 2012 23:15, Christian Mollekopf <chrigi_1 at fastmail.fm> wrote:

> On Monday 19 March 2012 20.22:32 Shaheed Haque wrote:
> > Hi,
> >
> > On 19 March 2012 08:50, Christian Mollekopf <chrigi_1 at fastmail.fm>
> wrote:
> > > On Sunday 18 March 2012 10.21:10 Shaheed Haque wrote:
> > >> David, thanks for confirming; I expect this is based on the notion of
> > >> recurrence that is in RFCs. In principle, I assume that we could
> > >> extend the EXDATE property with an X-param. Could the programming
> > >> model for the RecurrenceRule be extended to support this? I guess
> > >> korganizer would also have to understand the additional semantics, but
> > >> being able to save and restore the data would be a first step.
> > >>
> > >> Kevin, as I hinted, I suspect this is how Exchange represents things
> > >> internally. Certainly representing the innards in this way would give
> > >> complete flexibility.
> > >
> > > The standard way to do this in iCal is not to exclude & add a new
> Event,
> > > but to make use of RecurrenceID. This allows to add an event, matching
> a
> > > specific date of the recurrence-set using RecurreneceID, to change
> > > properties of either only that occurrence, or also all future events if
> > > THISANDFUTURE is set.
> > >
> > > https://tools.ietf.org/html/rfc5545#section-3.8.4.4
> > >
> > > Excluding and adding a new event is a bit of a hack because you loose
> the
> > > information that the event belongs to the recurrence.
> >
> > So, the idea is to "hook" the overriding entry to an instance of the
> > recurring entry - sounds interesting. Now, I'm probably not
> > understanding, but if we don't have an exclusion, then does the
> > Calendar program not show both the original instance and also the new
> > overriding entry? Or is it expected to have logic to do the right
> > thing here?
>
> The exception replaces the original event (respectively that specific
> occurrence, or also all future occurrences).
>
> The logic to expand recurrences is according to the rfc as follows.
>
> * Derive recurrence set from the recurrence-rule and start-date
> * Add further recurrence dates contained in the recurrence-date property
> * Remove exceptions from the exception-date property.
> * Apply changes from Recurrence exceptions matching a Recurrence ID (where
> a
> recurrence exception really just is a normal event which has a recurrence
> id).
>
> So KCalCore should notice if there are several events with the same UID,
> look
> for the Recurrence-ID in one of the conflicting events (which marks the
> exception), and then apply the exception at the specific occurrence
> specified by
> the recurrence-id.
>
> I don't think that's possible right now, but if we need that feature we
> should
> implement it according to the RFC.
>
> You can read that information more in detail in the chapters:
> * https://tools.ietf.org/html/rfc5545#section-3.8.4.4
> * https://tools.ietf.org/html/rfc5545#section-3.8.5
>
> Or my simplified take at it:
> http://wiki.kolab.org/User:Mollekopf/Drafts/KEP:17#Recurrences
>
> Cheers,
> Christian
>
> >
> > > Cheers,
> > > Christian
> > >
> > >> 2012/3/18 Kevin Krammer <krammer at kde.org>:
> > >> > On Sunday, 2012-03-18, Shaheed Haque wrote:
> > >> >> Hi,
> > >> >>
> > >> >> I've been looking into how Exchange handles exceptions to recurring
> > >> >> Calendar entries, and trying to map them to KCalCore. The basic
> notion
> > >> >> of having an Event with recurrences works fine, but the only
> support I
> > >> >> see for defining exceptions is to addExRule(RecurrenceRule). This
> is a
> > >> >> relatively poor fit for Exchange which support changes to the
> subject,
> > >> >> location and all sorts of other properties. OTOH, an exception in
> > >> >> Exchange has no ability to recur itself, which a RecurrenceRule can
> > >> >> clearly handle.
> > >> >>
> > >> >> Roughly speaking, an exception in Exchange is a cut-down one-off
> > >> >> Event, rather than a RecurrenceRule.
> > >> >>
> > >> >> Have I misunderstood how to use what is there, or are there any
> plans
> > >> >> to change the way exceptions work to allow them to have richer
> > >> >> semantics along the lines that Exchange supports?
> > >> >
> > >> > Would it be possible to add a recurrence exception so that the usual
> > >> > event
> > >> > does not appear of the specific date and additionally add a new
> child
> > >> > event for just that date?
> > >> >
> > >> > Cheers,
> > >> > Kevin
> > >> >
> > >> > --
> > >> > Kevin Krammer, KDE developer, xdg-utils developer
> > >> > KDE user support, developer mentoring
> > >> >
> > >> > _______________________________________________
> > >> > KDE PIM mailing list kde-pim at kde.org
> > >> > https://mail.kde.org/mailman/listinfo/kde-pim
> > >> > KDE PIM home page at http://pim.kde.org/
> > >>
> > >> _______________________________________________
> > >> KDE PIM mailing list kde-pim at kde.org
> > >> https://mail.kde.org/mailman/listinfo/kde-pim
> > >> KDE PIM home page at http://pim.kde.org/
> > >
> > > _______________________________________________
> > > KDE PIM mailing list kde-pim at kde.org
> > > https://mail.kde.org/mailman/listinfo/kde-pim
> > > KDE PIM home page at http://pim.kde.org/
> >
> > _______________________________________________
> > KDE PIM mailing list kde-pim at kde.org
> > https://mail.kde.org/mailman/listinfo/kde-pim
> > KDE PIM home page at http://pim.kde.org/
> _______________________________________________
> KDE PIM mailing list kde-pim at kde.org
> https://mail.kde.org/mailman/listinfo/kde-pim
> KDE PIM home page at http://pim.kde.org/
>
_______________________________________________
KDE PIM mailing list kde-pim at kde.org
https://mail.kde.org/mailman/listinfo/kde-pim
KDE PIM home page at http://pim.kde.org/