[CalendarServer-users] Activating Alarms

[Tyler Keating]

Cyrus,

On 2-Feb-07, at 9:55 AM, Cyrus Daboo wrote:

> Hi Tyler,
>
> --On February 2, 2007 9:40:18 AM -0600 Tyler Keating  
> <tylerkeating at mac.com> wrote:
>
>> I have a simple question.  Can the Calendar Server act on Alarm  
>> triggers?
>> Such as sending email or an HTTP POST?
>
> No - the server does not do that. I believe some calendar systems  
> do have a server-based automatic alarm system. At some point it  
> would be good to have something like this so that users don't need  
> to have their calendar clients on all the time to receive alarms.
>
> One problem right now is that the alarm definition in iCalendar may  
> not be flexible enough to cover the types of alarm one might need.  
> It does have an email option, but the other types "display" and  
> "audio" only make sense for a client. A better choice might be to  
> have a generic "uri" type that could be used to point to different  
> services (e.g. not only email, but im, telephone, pager etc).
>
> Better still would be to have an actual "alarm server" that is  
> smart in determining exactly how to alert a user at a particular  
> time (e.g. you could configure preferences to have alerts delivered  
> in different ways depending on the time of day, day of the week,  
> whether your IM status indicates you as "present" on a particular  
> machine etc).
>
> All pie-in-the-sky stuff right now, but it would be good to know if  
> people are interested in server-based alarm actions.
>
> -- 
> Cyrus Daboo
>

I thought as much, thanks.  I was hoping to save myself the trouble  
of creating some sort of "Alarm Daemon", so at least you have one  
person definitely interested in Calendar Server alarm actions.  And  
when I think about, email alarms only might be the best way to go.   
Here are my thoughts on it:

Because of my working life at a Telco, I know that there are some  
unified messaging products that redirect communications based on  
schedules, similar to what you describe.   But there is no way to  
connect directly between the Calendar Server and the Messaging  
Server, without a client pulling the strings and some opening up of  
the Messaging Server API.  Doing it all at the calendar server level,  
I think you would need to extend iCalendar with some new type of  
Component to describe messaging rules and endpoints (VCONTACT?).  So  
that when a "procedure" VALARM is triggered, the Calendar Server  
could check to see if the collection has a VCONTACT component and  
then call the predefined endpoints according to the time and priority  
or something like that.

This seems so complex to add to a calendar server, that I'm not so  
sure it isn't better left to a dedicated "Messaging Server" that  
would front (at least) a Mail server which the Calendar Server could  
send to when an alarm occurs.  The user of the Messaging Server would  
already have set up their rules for how they want to handle email at  
that time and from that sender and then the Messaging Server should  
be able to do things like you say: make a call and translate the  
email text into speech, make a call and play an attached recording  
from the email, chop the email into a collection of SMS messages or  
use it's IM gateway to determine that you're signed in and send you  
an IM.  However, if the Messaging Server doesn't exist, then the  
Calendar Server's email still goes through.

This way the calendar server would not need a massive extension to  
know how you want to be contacted when an alarm occurs, it just needs  
that extra bit of functionality to send email.  The only thing this  
solution is missing is that you have to manage a schedule of  
messaging rules externally to the calendar server.  But that doesn't  
mean that a client couldn't still display the messaging schedule  
alongside the user's calendars, especially if the Messaging server  
supports iCalendar and CalDAV.

I'm pretty new to this and I don't have the whole picture, but I  
think you should resist anyone's opinion to beef up the Calendar  
Server beyond email alarms and messing with iCalendar.   That said,  
my alarm daemon could really use that Darwin "Messaging" Server any  
day now or better yet your newly scoped "email alarm daemon" for  
Darwin Calendar Server could use it...

Always a pleasure,
Tyler