[Gpephone-devel] Examining inter-process communication (1) -- signal

[Florian Boor]

Hi,

YU Yijun RD-ILAB-PEK schrieb:
> DBus provides similar mechanism named signal to deal with this type of
> inter-process communication. However, when a signal is emitted, only
> those running processes can receive and handle it (right?).

You can do this with DBus as well, that's what the service files are used for.
These map DBus services to executables.

> I am thinking introducing this inter-process communication to the GPE
> Phone Edition. In the current implementation, one process can also
> notify other processes that something has happened, however, currently
> there is no notification register/un-register mechanism and the
> notification sender hard-codes to which processes it will notify. e.g.,
> the phone server can only notify the dialer application an incoming
> call. If any other applications want also to be notified an incoming
> call, the phone server source code has to be modified. 

I do not see it like this. With DBus you can have multiple scenarios in which
e.g. a client can just listen on some bus interface and wait for an event to
occur or a direct communication between objects using a proxy.
The status applets are examples for DBus clients that do not register their
namespace and therefore allow multiple applications listening on the same
signal. So if the phoneserver sends the signal level status message multiple
applications can listen to it. This should even be possible if one of the
applications registers this namespace which might be something the voicecall
application might want to do.

> After implementing the notification/signal mechanism, then we need to
> define a set of signals on the platform.

What we definitely should do is to have a place where we document the whole IPC
stuff and which signals are available from which application.

Greetings

Florian

-- 
The dream of yesterday                  Florian Boor
is the hope of today                    Tel: +49 271-771091-15
and the reality of tomorrow.            Fax: +49 271-771091-19
[Robert Hutchings Goddard, 1904]        florian.boor at kernelconcepts.de

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