org.freesmartphone.GSM.Network Signal Strength Signal

[Heikki Paajanen]

2008/6/25 Thomas Seiler <thseiler at gmail.com>:
> Lets assume that the phone has a standby-screen application that will
> be separate from the signal strength indicator widget, so both will
> have their own connection to DBUS, and both might have their separate
> event loop.
>
> The provider name is not something that changes a lot, but might
> change occationally, i.e. when you cross a border, or live somewhere
> nearby a border and get coverage from the other side.
>
> The signal strength on the other hand is a volatile information, that
> might change quite fast under certain situations (i.e. driving on a
> highway), which leads to a lot of messages.
>
> I my opinion, it would make sense to decouple these signals, i.e:
>
> <signal name="SignalStrengthChanged">
>   <arg type="i" name="strength"/>
> </signal>
>
> and
>
> <signal name="NetworkStatusChanged">
>  <arg type="s" name="provider_name"/>
>  <arg type="s" name="status"/>
> </signal>
>
> In that way, the standby screen application can filter for
> NetworkStatusChanged signals and will not be woken up for every signal
> strength update.
>
> A kind of subscription mechanism would be ideal for the signal
> strength signal, so that the signal is only generated, when an
> application actually listens for it.
> (i.e. avoiding loosing CPU Cycles and context switches during full
> screen video playback...)

At least in gsmd2 network status signal is sent only when registration
status changes (unsolicited +CREG) or someone requests network status.
It is the standy screens resposibility to decide how often and when
signal strength information needs to be updated.

> Unfortunately, I do not know enough of DBUS introspection magic to
> understand if the phone daemon can learn if some applications are
> currently listening for a signal.

I have the impression that there is no built in way to know. But I'm
not an expert :)


Hessu