There is a previous thread with this question, and hints at an answer, but I could not get it to work.
I have an ICS file. It validates. It looks like this:
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//WA//FRWEB//EN
BEGIN:VEVENT
UID:FRICAL201
SEQUENCE:0
DTSTAMP:20081108T151809Z
DTSTART:20081109T121200
SUMMARY:11/9/2008 12:12:00 PM TRIP FROM JFK AIRPORT (JFK)
LOCATION:JFK AIRPORT (JFK)
END:VEVENT
END:VCALENDAR
I double-click it and it goes into Outlook 2007 perfectly.
Then, I double-click another ICS file that looks like this:
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//WA//FRWEB//EN
BEGIN:VEVENT
METHOD:REQUEST
UID:FRICAL201
SEQUENCE:1
DTSTAMP:20081108T161809Z
DTSTART:20081109T121300
SUMMARY:11/9/2008 12:13:00 PM TRIP FROM JFK AIRPORT (JFK)
LOCATION:JFK AIRPORT (JFK)
END:VEVENT
END:VCALENDAR
As explained in the rfc, the UID is the same and the sequence number is one greater, so I expect outlook to update my previous event entry, but all it does is insert a second one.
How can I formulate the ICS file so that Outlook knows to update the event? The original poster in the thread I referenced above said he got it to respond with METHOD and ORGANIZER but in my experience METHOD has no effect and ORGANIZER causes undesirable behavior where Outlook wants to email the event to someone. I just want it to update the calendar.
Best Answer
I got a hold of Tom Carter, the guy who started the original thread. He had a working example with a request followed by a cancellation. What I had wrong was my METHOD was inside my VEVENT when it should have been outside. So here is a working update!
Original:
Update:
All I did was add the request method (in the correct spot!), and an organizer.