dbus: Synchronous Methods
4 Calling methods in a blocking way.
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Methods can be called synchronously (“blocking”) or asynchronously
(“non-blocking”).
At D-Bus level, a method call consist of two messages: one message
which carries the input parameters to the object owning the method to be
called, and a reply message returning the resulting output parameters
from the object.
-- Function: dbus-call-method bus service path interface method
&optional :timeout timeout &rest args
This function calls METHOD on the D-Bus BUS. BUS is either the
symbol ‘:system’ or the symbol ‘:session’.
SERVICE is the D-Bus service name to be used. PATH is the D-Bus
object path, SERVICE is registered at. INTERFACE is an interface
offered by SERVICE. It must provide METHOD.
If the parameter ‘:timeout’ is given, the following integer TIMEOUT
specifies the maximum number of milliseconds the method call must
return. The default value is 25,000. If the method call doesn’t
return in time, a D-Bus error is raised (
Errors and
Events).
All other arguments args are passed to METHOD as arguments. They
are converted into D-Bus types as described in Type
Conversion.
The function returns the resulting values of METHOD as a list of
Lisp objects, according to the type conversion rules described in
Type Conversion. Example:
(dbus-call-method
:session "org.gnome.seahorse" "/org/gnome/seahorse/keys/openpgp"
"org.gnome.seahorse.Keys" "GetKeyField"
"openpgp:657984B8C7A966DD" "simple-name")
⇒ (t ("Philip R. Zimmermann"))
If the result of the method call is just one value, the converted
Lisp object is returned instead of a list containing this single
Lisp object. Example:
(dbus-call-method
:system "org.freedesktop.Hal"
"/org/freedesktop/Hal/devices/computer"
"org.freedesktop.Hal.Device" "GetPropertyString"
"system.kernel.machine")
⇒ "i686"
With the ‘dbus-introspect’ function it is possible to explore the
interfaces of ‘org.freedesktop.Hal’ service. It offers the
interfaces ‘org.freedesktop.Hal.Manager’ for the object at the path
‘/org/freedesktop/Hal/Manager’ as well as the interface
‘org.freedesktop.Hal.Device’ for all objects prefixed with the path
‘/org/freedesktop/Hal/devices’. With the methods ‘GetAllDevices’
and ‘GetAllProperties’, it is simple to emulate the ‘lshal’ command
on GNU/Linux systems:
(dolist (device
(dbus-call-method
:system "org.freedesktop.Hal"
"/org/freedesktop/Hal/Manager"
"org.freedesktop.Hal.Manager" "GetAllDevices"))
(message "\nudi = %s" device)
(dolist (properties
(dbus-call-method
:system "org.freedesktop.Hal" device
"org.freedesktop.Hal.Device" "GetAllProperties"))
(message " %s = %S"
(car properties) (or (caar (cdr properties)) ""))))
⊣ "udi = /org/freedesktop/Hal/devices/computer
info.addons = (\"hald-addon-acpi\")
info.bus = \"unknown\"
info.product = \"Computer\"
info.subsystem = \"unknown\"
info.udi = \"/org/freedesktop/Hal/devices/computer\"
linux.sysfs_path_device = \"(none)\"
power_management.acpi.linux.version = \"20051216\"
power_management.can_suspend_to_disk = t
power_management.can_suspend_to_ram = \"\"
power_management.type = \"acpi\"
smbios.bios.release_date = \"11/07/2001\"
system.chassis.manufacturer = \"COMPAL\"
system.chassis.type = \"Notebook\"
system.firmware.release_date = \"03/19/2005\"
..."
Info Catalog
dbus: Type Conversion
dbus: Top
dbus: Asynchronous Methods