[calsify] JSCalendar duration vs. end time

[Robert Stepanek <[e-mail]>]

During CalConnect XLIV in Zurich last week, discussion arose if the
JSCalendar duration property is enough to define the time span of an
event, or if an end time should be allowed as well (see the latest
spec here[1]).
Two arguments were raised in favor of adding an end time
 * It simplifies translation of VEVENTs with DTSTART/DTEND from
   iCalendar.
 * It allows to specify recurring events with a fixed end time even in
   case of time gaps (e.g. a recurring night club that has to close at a
   fixed time for legal reasons).
Our main concerns with adding an end time are:
 * Having two representations to define an event time span adds
   complexity. This contradicts the stated goals of JSCalendar.
 * Translation of DTSTART/DTEND to duration for one-time events is in
   almost all cases trivial. It does not require to rewrite existing
   calendar data.
 * The "night club scenario" isn't covered by iCalendar either, as the
   same exact duration of a recurring even with DTEND must be applied to
   all members of the generated recurrence set (see RFC 5545, section
   3.8.5.3). If anything, this scenario speaks for a new parameter on
   the RRULE.
 * Durations are guaranteed to be zero or positive, which makes it
   harder to produce invalid events.
As it currently stands we therefore see no need for an end time
property. Please let us know if you disagree.
Thanks,
Robert








Links:

  1. https://tools.ietf.org/html/draft-ietf-calext-jscalendar-11