dbus-register-method and introspection

dbus-register-method and introspection

[Rahguzar]

Hello all,

I am playing with the d-bus integration in Emacs 29.0.91. When I
register a method with `dbus-register-method` I am unable to see what
effect it has had. For example if I evaluate the following code in the
node (dbus) Register Objects of the manual,


(defun my-dbus-method-handler (filename) (if (find-file filename)
  '(:boolean t) '(:boolean nil)))

(dbus-register-method :session "org.freedesktop.TextEditor"
 "/org/freedesktop/TextEditor" "org.freedesktop.TextEditor" "OpenFile"
 #'my-dbus-method-handler)

and then evaluate

(dbus-introspect-xml :session "org.freedesktop.TextEditor"
"/org/freedesktop/TextEditor")

I get nil. Similarly I can see the service 'org.freedesktop.TextEditor'
in the application 'd-feet' but clicking on it doesn't show the method
that was registered above and after a while I get a timeout error. This
is in contrast to other services for which I can see what interfaces and
methods they provide.

Is there a simple way to expose such information for the services
provided from inside emacs?

Thanks in advance,
Rahguzar

Re: dbus-register-method and introspection

[Michael Albinus]

Rahguzar <rahguzar@zohomail.eu> writes:

> Hello all,

Hi Rahguzar,

> I am playing with the d-bus integration in Emacs 29.0.91. When I
> register a method with `dbus-register-method` I am unable to see what
> effect it has had. For example if I evaluate the following code in the
> node (dbus) Register Objects of the manual,
>
>
> (defun my-dbus-method-handler (filename) (if (find-file filename)
>   '(:boolean t) '(:boolean nil)))
>
> (dbus-register-method :session "org.freedesktop.TextEditor"
>  "/org/freedesktop/TextEditor" "org.freedesktop.TextEditor" "OpenFile"
>  #'my-dbus-method-handler)
>
> and then evaluate
>
> (dbus-introspect-xml :session "org.freedesktop.TextEditor"
> "/org/freedesktop/TextEditor")
>
> I get nil. Similarly I can see the service 'org.freedesktop.TextEditor'
> in the application 'd-feet' but clicking on it doesn't show the method
> that was registered above and after a while I get a timeout error. This
> is in contrast to other services for which I can see what interfaces and
> methods they provide.
>
> Is there a simple way to expose such information for the services
> provided from inside emacs?

The dbus-introspect-* methods work over the
"org.freedesktop.DBus.Introspectable" interface. You must provide an own
implementation for this with your "org.freedesktop.TextEditor" service,
if you want to see the introspection data.

Most existing D-Bus services provide an own file with that data, see
directory /usr/share/dbus-1/interfaces (on my Fedora system, it could be
somewhere else on your system). When this interface is called, they
simply dump out the respective file.

> Thanks in advance,
> Rahguzar

Best regards, Michael.

Re: dbus-register-method and introspection

[Rahguzar]

Hi Michael,
 Thanks for the reply.

Michael Albinus <michael.albinus@gmx.de> writes:

> The dbus-introspect-* methods work over the
> "org.freedesktop.DBus.Introspectable" interface. You must provide an own
> implementation for this with your "org.freedesktop.TextEditor" service,
> if you want to see the introspection data.
>
> Most existing D-Bus services provide an own file with that data, see
> directory /usr/share/dbus-1/interfaces (on my Fedora system, it could be
> somewhere else on your system). When this interface is called, they
> simply dump out the respective file.
>

I was somehow hoping that since the methods need to be registered, d-bus
had some magical way of determining at least which methods a service
provided. That not being the case, is there some way of using the
information provided to `dbus-register-method` to provide a rudimentary
implementation of introspection methods?


> Best regards, Michael.

Thanks again,
Rahguzar

Re: dbus-register-method and introspection

[Michael Albinus]

Rahguzar <rahguzar@zohomail.eu> writes:

> Hi Michael,

Hi Rahguzar,

> I was somehow hoping that since the methods need to be registered, d-bus
> had some magical way of determining at least which methods a service
> provided. That not being the case, is there some way of using the
> information provided to `dbus-register-method` to provide a rudimentary
> implementation of introspection methods?

There is the GNU ELPA package dbus-codegen, which provides some
support. I haven't used it myself, so I cannot say too much about.

> Thanks again,
> Rahguzar

Best regards, Michael.