[maemo-developers] [maemo-developers] Ideal way to develop a long-running app?

[From: Igor Stoppa]

Hi,
you want to write a power savvy application, then.
Few basic advices, which are also useful from a performance point of
view (sorry if i'm stating the obvious but there's really no trick
involved):
-avoid polling: polling is generally bad, it's useful only for very
tight loops that usually are not involved when writing apps
-avoid busy looping (see polling): a significant amount of power is
saved only when the processor is really idle, therefore ever call to
sleep functions is fine, when you need to wait for something. If it's an
asynchronous event that you are waiting for, then you can probably
execute some sort of blocking call that will effectively prevent
execution of your app until the data it's waiting for is really
available
-don't perform unnecessary activity: if the screen is blank, there is no
need to update it, if you can manage to quickly redraw it when it's
unblanked; however you can surely stops animations effects, such as
glowing blinking and similar
-don't abuse of connectivity resources like bt or wlan

I hope this few points will help you

br, igor

On Tue, 2005-12-20 at 00:28 -0500, ext Peter Kahle wrote:
> Hi,
> 
> I'm new to Maemo, and to developing for small/embedded devices in  
> general. I'm trying to wrap my head around the whole concept,  
> especially the 'killable' apps that Maemo enables. I'm trying to  
> figure how long-running but mostly ignored apps like IM clients fit  
> into the whole picture. Sure, you can just mark them killable=false,  
> but that seems inefficient. So I'd like someone to tell me what's  
> wrong with the following scenario:
> 
> Instant Messaging Application, designed from the ground up for Maemo,  
> architected in 3 or 4 parts:
> 
> Backend: No GUI but uses libosso, handles all the connection details,  
> buddy list, etc. Stores incoming IMs and uses auto-save to persist  
> them until they're seen. Auto-started on if-up if so configured, or  
> launched by dbus from the front end. killable=false.
> 
> Frontend: Only GUI, receives dbus messages from backend and displays  
> them to user. Also handles management and configuration of the  
> accounts and buddy lists. killable=true. Launched by maemo-launcher,  
> if that saves memory/time.
> 
> Statusbar and/or home applet: Displays some sign that there are (not)  
> new IM's that haven't been shown. launches frontend on click/ 
> doubleclick/whatever.
> 
> So what am I missing? The most likely is that process overhead  
> overshadows the memory saved by only running the GUI portions when  
> needed. And the obvious complexity of the system. What else?
> 
> Thanks,
> 
> Peter
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