[caldeveloper-l] Proposed draft: Caldav-scheduling-controls

[Bron Gondwana]

On Wed, Jun 6, 2018, at 08:56, Helge Heß wrote:
>> # Scheduling-Enabled header
> 
> I wanted to have that thing for a looong time.
> 
> I don’t like the header a lot, I’d prefer something like
> 
>   Scheduling: none / internal / all / X-??
> 
> over
> 
>   Scheduling-Enabled: F

I am happy with either.  The default would be "all" of course in
your example.
> I think the reason why people have been reluctant introducing that is
> that if you have this header, you can’t reliably know anymore whether
> something was scheduled or not (and a big motivation was that this
> decision MUST be taken off the client, because unreliable).
This has always annoyed me that the client can't even be trusted to send
a header, particularly since it could have been made compulsory. Anyway,
water under a bridge.  I much prefer explicitly requested side-effects
over implicit side effects (aka:magic) as a protocol design philosophy.
> What I don’t remember is how bulk-upload deals with that
> (https://github.com/evert/calendarserver-extensions/blob/master/calendarserver-bulk-change.txt)
> . Is that implicitly off, does it explicitly support the
> functionality?> 
> 
>> # Schedule-Address header
> 
> I don’t understand this one. CalDAV does support aliases in the address-
> set. And when setting an attendee it is the clients choice which
> address to use (either as the EMAIL attribute or the attendee URI).
What does your server do if two of the addresses in address set are
invited? What do you do if the user has an alias *@example.com but there
are some carve-out addresses which belong to somebody else?
Bron

> 
> hh
> 
>> On 6. Jun 2018, at 00:40, Bron Gondwana
>> <brong at fastmailteam.com> wrote:>> 
>> # Scheduling-Enabled header
>> 
>> RFC6638 Section 8.1 defines the Schedule-Reply header to suppress server-
>> sent scheduling messages when removing a resource (e.g. when cleaning
>> up spam), however there are other situations in which a client may
>> wish to update the resource stored on a server without sending
>> scheduling resources, for example:>> 
>> * Migrating an existing calendar from one server to another (e.g.
>>   changing providers)>> * Restoring a calendar from backup after data loss
>> * keeping a synchronised copy of another calendar for backup, caching
>>   or aggregation purposes>> 
>> Setting schedule-agent to CLIENT is not a good solution, because
>> other clients will continue to leave the value set to CLIENT and then
>> scheduling won't work on that event.>> 
>> So - I propose replacing and/or supplementing "Schedule-Reply: F"
>> with another header - "Scheduling-Enabled: F" which suppresses all
>> scheduling actions on the server, and stores the resource as-is.
>> This is an HTTP header on the PUT action, and the resource can then
>> be interacted with normally by clients.>> 
>> # Schedule-Address header
>> 
>> Email has the concept of aliases, however CalDAV does not.  When
>> storing or updating a resource, the server calculates which of the
>> ORGANIZER or ATTENDEE properties refers to the acting user by looking
>> at the calendar-user-address property on the calendar, or by the
>> username of the authenticated user.  This header provides a way for
>> the client to tell the server "this is the address I am acting as",
>> overriding those hints.>> 
>> ====
>> 
>> With these two headers, it's possible to use CalDAV for all
>> interactions with the server, without needing a separate protocol
>> for backup restore or for injecting iMIP messages sent to
>> aliases.  I assume I'd also need a way to define in some server
>> info on the server that these headers were supported - so I'd
>> love suggestions there.>> 
>> I'm happy to write this up as an IETF draft and bring it to calext,
>> particularly if there's general support of the idea.  I'm happy to
>> consider new names for the headers as well - it's pretty easy to
>> change on our server and client code at FastMail.  Both these headers
>> are implemented and in production on our systems.>> 
>> ====
>> 
>> Cheers,
>> 
>> Bron.
>> 
>> --
>> Bron Gondwana, CEO, FastMail Pty Ltd
>> brong at fastmailteam.com
>> 
>> 
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--
  Bron Gondwana, CEO, FastMail Pty Ltd
  brong at fastmailteam.com

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