[Tickets #12773] Re: Thunderbird lightning caldav serial event time failure with summer/wintertime change

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Ticket URL: http://bugs.horde.org/ticket/12773
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  Ticket             | 12773
  Updated By         | benrose at math.princeton.edu
  Summary            | Thunderbird lightning caldav serial event time failure
                     | with summer/wintertime change
  Queue              | Kronolith
  Version            | 4.1.3
  Type               | Bug
  State              | Not A Bug
  Priority           | 1. Low
  Milestone          |
  Patch              |
  Owners             |
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benrose at math.princeton.edu (2014-03-05 19:31) wrote:

Hi,

I have some more information. I do not see the bug in the kronolith  
webgui itself. I also do not see the bug when I connect my Android to  
ActiveSync. But, I DO see the bug when I download my ICS file and  
import it into any client. The same goes for webdav. So the question  
is what processing is done differently on an ActiveSync connection  
than in a regular ICS file? How is timezone data swapped in ActiveSync?

For reference purposes, I downloaded my personal calendar from google  
in ICS format. Looking at an individual event:

BEGIN:VEVENT
DTSTART;TZID=America/New_York:20140221T140000
DTEND;TZID=America/New_York:20140221T150000
RRULE:FREQ=WEEKLY;BYDAY=FR
EXDATE;TZID=America/New_York:20140314T140000
DTSTAMP:20140305T190333Z
UID:d1jg92liohlcpe4pc6nn3hl4is at google.com
CREATED:20140212T023446Z
DESCRIPTION:
LAST-MODIFIED:20140218T163947Z
LOCATION:
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:Weekly One-on-One with Alice
TRANSP:OPAQUE
END:VEVENT

I see a few things in contrast to an individual event as defined by  
Horde's ICS file:

BEGIN:VEVENT
DTSTART:20140220T190000Z
DTEND:20140220T200002Z
DTSTAMP:20140305T152044Z
UID:20140217112844.M7XYoy9TtQiwYOvfqo8h9w5 at webmail.MYDOMAIN.COM
CREATED:20140217T162937Z
LAST-MODIFIED:20140304T194922Z
SUMMARY:Bob - Individual Weekly Meeting
CLASS:PUBLIC
STATUS:CONFIRMED
TRANSP:OPAQUE
RRULE:FREQ=WEEKLY;INTERVAL=1;BYDAY=TH
EXDATE;TZID=America/New_York:20140220T190000Z
END:VEVENT

Is it proper for Horde to not put the timezone in the dtstart and  
dtend fields? Right now Horde is saying the event occurs from 19:00  
Zulu to 20:00 Zulu instead of saying 14:00-15:00 America/New_York.  
When Daylight Saving Time hits, Zulu time and America/New_York change  
relative to one-another as there is no DST in UTC.

I also noticed at the beginning of the ICS file that google calendar  
gave, there is a section like this:

BEGIN:VTIMEZONE
TZID:America/New_York
X-LIC-LOCATION:America/New_York
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:19700308T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:19701101T020000
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
END:STANDARD
END:VTIMEZONE

This seems to pretty clearly define DST behavior for the calendar  
software. This entire section is absent in the Horde ICS file.

I am updating this ticket with this information following sending same  
to the horde mailing list for discussion.