[Chandler-dev] Network operations for a "subscribe"

[Grant Baillie]

On 5 Dec, 2006, at 13:35, Brian Moseley wrote:

> On 12/5/06, Morgen Sagen <morgen at osafoundation.org> wrote:
>> One problem with
>> this code is that Cosmo currently responds to a GET on a CalDAV
>> calendar with an icalendar file of all the contained events, and thus
>> if Chandler follows this algorithm it won't be able to subscribe to a
>> Cosmo collection in CalDAV mode (Chandler would simply treat the
>> collection as a monolithic ical file).
>
> in 0.6, cosmo will have separate urls for webcal and dav:
>
> * GET on the webcal url will get you a monolithic icalendar resource,
> but PROPFIND will get you a 405.
>
> * GET on the dav url will get you a html directory listing (including
> alt links to the collection via webcal, ui, morse code, atom), and
> PROPFIND will get you a 207.
>
> note that caldav provides a very specific mechanism to determine if a
> resource is a calendar collection: PROPFIND the url and look at the
> DAV:resourcetype property to see if it contains the
> <CALDAV:collection/> element.

So far as I know GET on the URL will cause a large download from  
Apple's server (as well as the current but soon-to-be-obsoleted Cosmo  
behaviour), and will also miss out on the CalDAV-ness of the  
collection. Maybe, to do a subscribe, Chandler should do a PROPFIND  
first, asking for at least:

- ACL (current-user-privilege-set)
- getcontenttype
- resourcetype

If that fails, we would revert to webcal mode (i.e. just GET the URL  
if it's text/calendar).

As a general question, how would we know when a dav URL supports eim 
+xml? Is there a separate DAV property (or added DAV:resourcetype)  
for that?

--Grant