Support for alarms

[tobixen]

The processing of alarms as described in https://tools.ietf.org/html/rfc4791#section-8.6 is outside the scope of the caldav library, possibly with the exception of sending emails. Anyway, the library should support methods for alarm discovery.

[newhinton]

will this include setting new alarms?

[tobixen]

Setting new alarms is possible through the library today. It's part of the icalendar data sent to the server, generation of this data is outside the scope of the caldav library.

[tobixen]

generation of this data is outside the scope of the caldav library.

I have reconsidered this a bit.

So, to fully support alarms, I think we may need to support ...

Adding alarms

It's always possible to add alarms by editing the raw icalendar, or editing it via the vobject_instance or icalendar_instance properties. However, recently we've started adding multiple "high level" convenience methods and parameters for editing and generating icalendar code, so we may as well add explicit support for alarms. So it's needed with:

• The possibility to add simple alarms through parameters to the save_*-methods.
• Possibility to add simple alarms to an existing Event/Todo-object

Finding alarms

• The search-method (introduced in the upcoming v0.10 version) should be fixed to allow searching for alarms by a time range search
• The calendar object should have a method find_upcoming_alarm(after=now, cnt=1) for finding upcoming alarm(s).

Processing alarms

The RFC defines four kind of alarm actions, it's sound, display, email and procedure. This library is definitively not going to play and sounds or display something for the end user. This library could theoretically send emails or launch procedures. However, since this library does not have any kind of event loop or other means of getting the timing correct, I feel that all kind of processing is out of the scope for this library and should be taken care of by the caller.

[tobixen]

• Adding of alarms (without having to hand-craft the icalendar data) is supported in #221
• Searching for events/todos based on alarm time is supported in #221, but not tested
• Searching for "upcoming alarms" not supported yet, procrastinating it

If anyone has a great needs for alarms, I will prioritize this and get it merged, testing it towards a calendar server that supports searching for alarms. It seems like neither radicale nor xandikos supports searching for alarms yet, and those two are my primary test servers.

[tobixen]

So I basically wrote some code (but no documentation) for adding alarms easily to new events long long time ago, but got busy with other things. I will try to prioritize to get it merged in, problem is that I have no idea when I will get time to do any work towards the caldav library next time. Perhaps tomorrow, perhaps next week, perhaps next month ...