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

From: [email-masked]
Date: Thu, 12 Jun 2003 16:01:45 -0400

Doug claimed on 05/30/2003 04:53:56 PM:
> So if SEQUENCE:1 changes 100% of all instances.
> Then SEQUENCE:2 trying to cancel one of the new (SEQUENCE:1 instances.
> 
> You can't becaues you would have no idea what was being canceled
> if the RECURRENCE-ID refer to the SEQUENCE:0 instances.

You can easily if the RECURRENCE-ID never changes. 

The CANCEL for UID/RECURRENCE-ID has a higher SEQUENCE value so it 
obsoletes the previous SEQUENCE data for that instance.  Even if you never 
got SEQUENCE:1 you can properly identify the SEQUENCE:0 instance and mark 
it CANCELed.  If the SEQUENCE:1 comes in later then its already been 
obsoleted (by iTIP Section 2.1.5, Rule #2) and can be safely ignored.

If however you expect to rewrite the RECURRENCE-ID value for every new 
SEQUENCE then you run into the same kinds of problems you do if you miss a 
SEQUENCE.  Its not possible to recover NOR can you act on SEQUENCE:2 until 
you get SEQUENCE:1.  Or more generally, you cannot act on SEQUENCE:x 
unless you are currently at SEQUENCE:x-1 and since a REFRESH is always 
guaranteed to be at the latest SEQUENCE (x in this case). 

This topic is going nowhere since this has been discussed before (July 
1999, "Recurrence ID changes?") and there has been no attempt to 
demonstrate how it could possibly work using actual iTIP data. 

Unless Doug or George can demonstate how to resync, etc using a delta 
model I suggest we make a strong WG note to remove the misleading text 
from the next revision of 2445 and move on.

Bruce
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---

From: Doug Royer <[email-masked]>
Date: Thu, 12 Jun 2003 14:46:31 -0600

> You can easily if the RECURRENCE-ID never changes.  

1) Unless you do not have it because you joined the event
    after SEQUENCE:0 was obsoleted.

2) Unless NONE of the current instances match up to ANY
    of the original instances.

> from the next revision of 2445 and move on.

You do not have to SYNC - simply do a REFRESH and get the latest object
version.

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