Re: [Task Scheduler] Repeating alarms

I am OK with recurring alarms, but what is supposed to happen if the device
is off and an alarm cannot be met?

Kenneth


On Wed, Nov 13, 2013 at 1:38 PM, John Mellor <johnme@google.com> wrote:

> I notice that the API only allows one-shot alarms (setTimeout style), so
> apps that want to run periodically (both at exact times like a recurring
> alarm/calendar event, and inexact times like background syncing) must
> schedule a new task every time their task gets started.
>
> That helps to keep the API nice and simple, but I worry that it might
> cause sporadic failures. Specifically, if the app crashes, gets killed, or
> hits an exception, in between the task starting and the app scheduling its
> next execution, it will never be run again (until the app is next manually
> launched, at which point a well-written app might check that the task is
> still scheduled, though many apps may neglect to do this).
>
> Two possible solutions:
>
> 1. Automatically schedule an additional task if a task crashes or gets
> killed. However, there's a risk that this would perform actions twice (e.g.
> if the background task sends an email, and we run an additional task with
> the same data, 2 emails might get sent); alternatively we could pass null
> data, but then that might confuse an app that only every schedules itself
> with data. So I'm not really sure this is workable.
>
> 2. Add a recurring alarm variant. It might make sense to only allow inexact
> alarms<http://lists.w3.org/Archives/Public/public-sysapps/2013Nov/0019.html> to
> automatically recur; this would also allow us to simplify the API, as with
> inexact alarms you don't actually need to specify an interval, instead the
> browser will heuristically determine how often you deserve to get run (or
> we could allow providing a "minimum interval", which is the period of time
> after a given task execution during which the task should *not* be run, and
> after that the browser can schedule the task whenever).
>
> What do people think?
> Thanks,
> John
>



-- 
Kenneth Rohde Christiansen
Web Platform Architect, Intel Corporation.
Phone  +45 4294 9458 ﹆﹆﹆