Re: an app that never quits
Re: an app that never quits
- Subject: Re: an app that never quits
- From: Jens Alfke <email@hidden>
- Date: Tue, 22 Sep 2009 09:06:27 -0700
On Sep 21, 2009, at 11:31 PM, Kyle Sluder wrote:
On Mon, Sep 21, 2009 at 11:30 PM, Erick Calder <email@hidden> wrote:
wow. ok. I guess that's not going to help much then. I must say
that
without daemons the range of applications possible seems rather
quite narrow
to me.
Background processing is a much-desired feature. You can add your
voice by filing a bug at http://bugreport.apple.com.
But keep in mind that the realities of battery power and 3G networks
limit the kind of background processing that's feasible — that's the
main reason Apple hasn't let 3rd party apps run in the background yet.
- If your daemon made a connection to a server every 15 minutes to
poll for data, it would reduce battery life. (Yes, the built-in mail
app does this if you're not using push notification, and that already
reduces battery life; adding more apps doing that would make it a lot
worse.)
- If your daemon opened a socket and left it open forever waiting for
messages, as IM services do, it would keep the device's radio active
to maintain IP connectivity, which would drain the battery.
Apple's push notification system uses a similar type of of GSM
signaling as SMS messages, so it doesn't require any extra overhead.
The carrier sends a signal when a push message is available, and the
device wakes up and makes a connection to retrieve the message data.
What is feasible, I think, is to allow the notifications to launch the
app in some kind of limited background mode where it can do a little
bit of processing and then either exit or alert the user. And the
notifications could contain larger payloads, so the app could operate
directly on the notification without having to make its own connection
to fetch data.
[Disclaimer: I'm not an expert on mobile devices, batteries or GSM/3G
radios. This is all stuff I've had explained to me over the past year
or two by people who know more than I do.]
—Jens_______________________________________________
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