[Dev] Subscribing to calendar URLs

[Grant Baillie]

On Feb 1, 2006, at 14:18, Morgen Sagen wrote:

>> On IRC earlier today, we had a user, Leppy, unable to subscribe to  
>> his Basecamp calendars (see <http://basecamphq.com/>) from  
>> Chandler; both Mozilla and Apple iCal both had no problems.
>>
>> What's going on here is that Chandler is getting itself confused  
>> about what kind of thing you're trying to subscribe to. It could  
>> be any of:
>>
>>   1. A simple text/calendar resource (i.e. a ".ics file on the web").
>>   2. A non-CalDAV Chandler WebDAV collection (i.e. cloud xml)
>>   3. A CalDAV collection
>>
>> ...
>>
> I'm for using the webcal scheme for detecting case #1; either that  
> or adding a checkbox to the subscribe dialog that lets the user  
> indicate which case it is.  It gets tough to auto-detect between #1  
> and #3 because Cosmo will actually return a monolithic .ics  
> calendar if you do a GET on a CalDAV collection (which is actually  
> a cool feature, it just makes it hard to auto-detect things).

Right. It's not so tough, though, IMHO: What I'm implementing now  
(i.e. for 0.7) is to send OPTIONS first:

-  If PROPFIND is allowed, we can use standard WebDAV to figure out  
whether it's 1, 2 or 3

- If it isn't, we can go ahead and use GET. I'd say that if GET shows  
a Content-Type that isn't text/calendar, we go ahead and try to parse  
it as ICalendar anyway, but report errors differently. (There seem to  
exist misconfigured servers out there, including the IRC user's, that  
report the Content-Type incorrectly).

--Grant