ubuntu-phone team mailing list archive

[John Lea <john.lea@xxxxxxxxxxxxx>]

From a design point of view, the guidance we are currently following is:

- Only the app in the foreground when the phone is unlocked is 
guaranteed to be running.

- In all cases where an app requires functionality that needs to run in 
the background and/or while the phone is locked, this functionality will 
need to be split off into a separate daemon that will be packaged and 
ship together with the foreground UI app.  The daemon will have no UI, 
and it's functions will be started and stopped using the foreground UI app.

Applying this guidance to the use cases below:


On 21/10/13 23:46, Jamie Strandboge wrote:
>   * a metronome app for musicians to practice to (2 are in the app store now)

The metronome app could be split into a UI app and daemon.  The UI app 
would start/stop the metronome and configure the sound/timing, and the 
daemon would play the sound.  The daemon would continue playing the 
sound irrespective of UI app state until the user switches the metronome 
off via the UI app.  This is useful in the case where a musician wants 
to set the metronome running, and then focus say a synthesiser app to 
practice on.

Just forcing the Metronome app to run when the phone is locked and the 
metronome app is in the foreground does not support this use case, the 
'UI app' and 'deamon' approach seems a better fit.

>   * a white noise app to help people sleep (1 in the store)

Again I think splitting the White Noise app into a separate UI app and a 
daemon that plays the sound is advantageous.  This is because the user 
might for example also want to run a separate Sleep Pattern monitoring 
app at the same time.  Restricting the White Noise app to only running 
when it is in the foreground (irrespective of the phone lock state) 
precludes this use case.  btw, the Sleep Pattern monitoring app would 
also be broken into a UI app and a deamon.

>   * a navigation app that speaks the directions to you as you drive (none in the
>     app store AFAIK, but this would be a wonderful addition)

I think the UI app / deamon split is a better solution for the problem 
as well (again because the user will sometimes want to perform other 
tasks while the navigation app continues to speak directions).

>   * internet radio apps (there are at least 2 in the store)

I think the UI app / deamon split works here?

>   * a 3rd party alarm clock (perhaps the API that the core app clock uses is
>     sufficient-- I haven't checked)

Same as above.

It looks to me like the UI app / deamon split solves all the use cases 
we have currently thought of, are there any reasons why we should not 
follow this approach in all these cases?

cheers,
John