Re: emacs-23.2-3 and DBus

[Ken Brown <kbrown at cornell dot edu>]

On 10/4/2010 11:47 PM, nyc4bos@aol.com wrote:
> Thank you for your work on incorporating Emacs and DBus!
>
> Can you tell me how you are testing it?
>
> I tried to use notifiations.el (from the Emacs 24 trunk).
>
> After loading it, Emacs appears to freeze and I see that
> the emacs and winlogin.exe processes consume almost all of
> the CPU.
>
> After about 30 to 45 minutes, I pressed `C-g' and saw the
> message "Back to top level.".
>
> However, Emacs is still frozen and the only thing I could
> do is to kill emacs from outside of emacs.

Please send Cygwin questions to the Cygwin mailing list, not to 
individual maintainers.

I know virtually nothing about D-Bus.  To test it, I simply followed the 
instructions given by Michael Albinus in the thread 
http://cygwin.com/ml/cygwin/2010-08/threads.html#00330 .  Here's a brief 
summary:

1. Start the messagebus service.

2. Start a dbus session (eval `dbus-launch --auto-syntax`) in a shell.

3. echo $DBUS_SESSION_BUS_ADDRESS .

4. In a different shell, set (and export) $DBUS_SESSION_BUS_ADDRESS to 
this value, and run dbus-monitor --session .

5. Start Emacs in the first shell, and load the dbus library.  You 
should see output from dbus-monitor in the other shell, showing that an 
application has started.  It will also tell you the name of that 
application, like ":1.1".

6. In Emacs, evaluate (dbus-get-unique-name :session) .  You should get 
the same name.

7. Register for signals sent by the D-Bus:

(defun my-dbus-signal-handler (&rest args)
  (message "Signal from bus %s received: %s"
           (dbus-event-bus-name last-input-event) args))

(dbus-register-signal
 :system dbus-service-dbus dbus-path-dbus dbus-interface-dbus
 "NameOwnerChanged" 'my-dbus-signal-handler)

(dbus-register-signal
 :session dbus-service-dbus dbus-path-dbus dbus-interface-dbus
 "NameOwnerChanged" 'my-dbus-signal-handler)

8. Now you could open any other D-Bus application, and you should be
notified in Emacs (in the echo area and the *Messages* buffer).  For 
example, you could try dbus-monitor --session , started in the same 
shell where you started Emacs.

I'm afraid that's all I know.  Unless you think there is a 
Cygwin-specific problem, further questions should probably be directed 
to one of the Emacs lists, where you will find people who are 
knowledgeable about D-Bus integration in Emacs.  BTW, there has been 
quite a bit of development of this integration since the release of 
Emacs 23.2.  Some improvements will appear in Emacs 23.3, and some won't 
appear until 24.1.  So if you're trying to use a library from the Emacs 
24 trunk, it's possible that it's simply not compatible with Emacs 23.

Ken

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