Subject: RE: Fw: Correct handling of Recurrence-id

From: [email-masked]
Date: Mon, 4 Aug 2003 11:52:38 -0400

Chris Olds replied on 06/12/2003 02:49:02 PM MST:
>In Bruce's model, I need to keep track of the original recurrence-id of 
each
>instance of an event as they evolve. 

Its NOT my model, its the model in iCalendar.  In case it was not clear, 
Im defending the existing model and prose from iCalendar/iTIP.  iCalendar 
clearly says:

   The date/time value is set to the time when the original recurrence
   instance would occur; meaning that if the intent is to change a
   Friday meeting to Thursday, the date/time is still set to the
   original Friday meeting.

Thats not my text, thats the WGs (via the authors).  Plus iTIP already 
mandates preserving UID / RECURRENCE-ID / SEQUENCE / DTSTAMP in Section 
2.1.5 with:

   Hence, CUAs must persist the following component properties: "UID",
   "RECURRENCE-ID", "SEQUENCE", and "DTSTAMP".  Furthermore, for each
   "ATTENDEE" property of a component CUAs must persist the "SEQUENCE"
   and "DTSTAMP" property values associated with the "Attendee's"
   response.

Its NOT difficult to preserve a property that does not change.  If you can 
do it for UID you can do it for RECURRENCE-ID. 

> In the REFRESH model, all I need to do
> is get the current version of the object and I'm done. 

In the REFRESH (aka 'delta') model, you MUST ignore the current version of 
the object if you do not have the version that immediately preceedes it. 
Otherwise you have NO way to match the RECURRENCE-ID to the proper 
instance.  The converse is true of the fixed RECURRENCE-ID (aka iCalendar) 
model.  If you missed an message, no big deal.  You just use the most 
recent one and you are done.  NO EXTRA WORKFLOW IS NECESSARY.

> If I have the current
> version, I can use a message with a RECURRENCE-ID to update my view of 
the
> object; if I don't have the current version, I just found that out and I 
can
> ask for a REFRESH and I'm done.

If RECURRENCE-ID changed on each reschedule then you cannot tell if you 
have the current version of the instance if you missed one or more 
reschedules!  Thats the problem w/the delta model...

Bruce
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