ubuntu-phone team mailing list archive

[Rasmus Eneman <Rasmus@xxxxxxxxx>]

>I do disagree with requiring the user to interact with the system to
>ensure longer battery life. We should try as hard as possible to make
>this automagically work.

>For a tech-savvyy audience: Yes. For everyday users I do disagree. In
>the end, users do blame the platform for bad battery life (for a good
>reason) and we certainly don't want to have battery life preserving
>apps in our app store (Google Play has got quite a few of them).
While automagically is great when it works, it's a real hassle when it
don't.
I agree that users will be put of if there is a lot of battery drain,
however
users will also be put of if they can't use their phone as they would expect
(Android have become huge and more and more users learn that they can
do things in the background on their phone too).

A golden path have to be found between features and battery. Personally
I think Android does pretty good here but I get a feeling that you don't?

>my point of view is still that forcing every little small app to bring its
own
>daemon will:
>
>a) scare off people for writing apps for our platform as the communication
>overhead between a service and the UI is a huge effort and easy to mess up.
Android have AIDL (http://developer.android.com/guide/components/aidl.html)
to help developers with this, I have used it and have to say that it's very
simple
to use. Hopefully something like this could come to Ubuntu too (it would
make
sense on the desktop as well).

>b) be suicide in terms of battery usage. This will cause exactly the
opposite
>than what it should. If everyone brings its own daemon we'll have tons of
>services running all the time and the user can't even stop them because
there
>is no UI to stop them.
Again: Android.
Android kills a service if the resources are needed, if the developer wants
to
create an app which have a responsible chance to stay alive even if the user
does something else he have to create an ongoing notification. This makes
to user aware that the app is running.


2013/10/22 Jamie Strandboge <jamie@xxxxxxxxxxxxx>

> Pulling in Zoltan, Daniel and David for comment
>
> On 10/22/2013 05:40 AM, Thomas Voß wrote:
> > On Tue, Oct 22, 2013 at 12:33 PM, John Lea <john.lea@xxxxxxxxxxxxx>
> wrote:
> >> 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?
> >>
> >
> > Nope, I do fully agree with your examples here. And it is close to the
> > aforementioned Activity/Service approach.
> >
>
> It sounds like what we are saying is that we don't have to change anything
> in
> the system, we just need to communicate to developers how they should
> program
> within the system for these sorts of apps.
>
> Sounds like what is needed here is:
>  * the SDK to treat compiled apps as first class citizens (I know this is
>    planned, perhaps Zoltan can comment on its status)
>  * documentation on developer.ubuntu.com that explains in developer terms
> how
>    power management and application lifecycle work, specifically for HTML5,
>    Cordova, pure QML and this new QML ui with background service. I did
>    something similar for application confinement[1] which has been quite
> helpful
>  * provide an example QML ui with background daemon. We have a pure QML
>    tutorial[2][3] for a currency converter. Perhaps a simple white noise
> app
>    that uses qtmultimedia in the backend service would be a good example
>    (though a simple metronome might be better since the white noise app
> could
>    in theory use the media service). The docs[2] could call this 'QML with
>    background service' (or something)
>
> If we did the above, app developers know where they stand and they can get
> their
> work done now while we build out various system services and SDK support to
> better support common use cases. Daniel and David, what do you think about
> changes like this for http://developer.ubuntu.com? Does it make sense?
>
> [1]
> http://developer.ubuntu.com/publish/apps/security-policy-for-click-packages/
> [2]http://developer.ubuntu.com/apps/
> [3]http://developer.ubuntu.com/apps/qml/tutorial/
>
> --
> Jamie Strandboge                 http://www.ubuntu.com/
>
>
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>


-- 
Rasmus Eneman