[Ietf-caldav] Re: Notifications [was Re: Client work]
lisa at osafoundation.org
Mon Aug 16 13:29:23 PDT 2004
> Personally my goal is too bring as many _available_ servers and
> clients together - I'm not sure about your intention (produce a spec
> which covers all features of Chandler?).
That's certainly not my goal -- that would not be conducive to
developing a standard, let alone to achieving interoperability. My
goal was to maximize interoperability and usability together, which of
course trade off against each other. Interoperability could be
achieved almost trivially with a trivial standard but it wouldn't be
very usable. Usability could be maximized with a complex protocol but
it would be only theoretical usability without good interoperability.
CalDAV is a stab at a compromise there and I welcome input from this
list on where the balance should lie.
> Currently the only "protocol" which is more or less interoperable
> between servers is iCal-File-over-HTTP. And this one is really
> inappropriate for almost anything ;-)
> For OGo we "solve" the situation only by implementing all the various
> protocols starting with iCal/HTTP, Exchange WebDAV, WCAP,
> XML-RPC(variants), RSS etc used by the clients. It is a mess that this
> is required even for basic things.
> To summarize: my _strong_ fear is that if CalDAV ends up being too
> complex, few will implement it. The mentioned notification is
> certainly one thing which would require a major amount of work in
> existing servers (including OGo and PHPgroupware).
What do you think is too complex? Evidently you think DASL is not too
complex but Jabber is; that's interesting because it's not the same
position others would necessarily take, since so many XMPP /Jabber
libraries exist but few (none?) DASL libraries.
> Maybe the "level" idea is good?:
> CalDAV Level 0: basic DAV/iCal storage of iCal objects + DASL queries
> CalDAV Level 1: Level 0 + more complex cal support (fanout, reports?)
> CalDAV Level 2: Level 1 + Jabber notifications
> What do you think? A calendaring system can work without level 1 and 2
> features. Instead of levels we could also use separate documents (like
> WebDAV ACL and DASL is separate from WebDAV and certainly not required
> for a lot of clients).
> (BTW: I think it is already hard enough to make other server vendors
> implement DAV/DASL/ACLs properly ..., I already did a lot of talks
> with PHPgroupware and exchange4linux people on this ;-)
Cyrus also proposed CalDAV "levels" where the first level was basically
what Apple does with iCal, so an even simpler "Level 0" than what you
The reason ACL is a requirement in CalDAV is because the requirements
investigation that the CalSch WG did resulted in deciding that access
control was a requirement for a calendar access protocol. I don't
think it's actually a requirement, but I'd like some kind of rough
consensus before making it optional.
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