The D-Bus library is a messaging library used by various desktop environments (GNOME, KDE, etc) for interprocess communication.
There are multiple Python bindings for DBus:
GDbus and QtDbus are wrappers over the C/C++ APIs of GLib and Qt
pydbus is a modern, pythonic API with the goal of being as invisible a layer between the exported API and its user as possible
dbus-python is a legacy API, built with a deprecated dbus-glib library, and involving a lot of type-guessing (despite "explicit is better than implicit" and "resist the temptation to guess").
txdbus is a native Python implementation of the D-Bus protocol for the Twisted networking framework.
See also: DBusBindings on Freedesktop wiki.
The dbus-viewer and qdbusviewer programs let you browse through the services and interfaces available on your system.
pydbus
For more information see pydbus's Readme.
Introspection
from pydbus import SessionBus
bus = SessionBus()
# Create an object that will proxy for a particular remote object.
remote_object = bus.get(
"org.freedesktop.DBus", # Bus name
"/org/freedesktop/DBus" # Object path
)
# Introspection returns an XML document containing information
# about the methods supported by an interface.
print ("Introspection data:\n")
print (remote_object.Introspect()[0])Output:
Introspection data:
<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node>
<interface name="org.freedesktop.DBus.Introspectable">
<method name="Introspect">
<arg name="data" direction="out" type="s"/>
</method>
</interface>
<interface name="org.freedesktop.DBus">
<method name="RequestName">
<arg direction="in" type="s"/>
<arg direction="in" type="u"/>
<arg direction="out" type="u"/>
</method>
...
Calling an interface method
After executing the introspection example:
print(remote_object.ListNames()[0])
Output:
['org.freedesktop.DBus', 'org.freedesktop.Notifications', 'org.freedesktop.PowerManagement', ':1.8', ':1.9', 'org.kde.kaccess', 'org.kde.kded', 'org.kde.StatusNotifierItem-655-1', 'org.freedesktop.systemd1', 'org.ktorrent.ktorrent', 'org.kde.StatusNotifierItem-656-1', 'org.kde.konversation', 'org.pulseaudio.Server', 'org.kde.KScreen', 'org.kde.krunner', 'org.kde.konsole', ':1.40', 'org.a11y.Bus', ':1.41', ':1.42', ':1.20', ':1.43', 'org.kde.klauncher5', ':1.21', ':1.23', 'org.kde.dolphin-3012', 'org.freedesktop.PowerManagement.Inhibit', 'org.kde.Solid.PowerManagement', ':1.24', ':1.25', ':1.49', 'org.kde.kmix', 'org.kde.screensaver', 'org.kde.KWin', 'org.bluez.obex', ':1.29', 'ca.desrt.dconf', 'org.kde.kgpg', 'org.freedesktop.ScreenSaver', 'org.kde.plasmashell', 'org.kde.plasmanetworkmanagement', 'org.kde.StatusNotifierItem-666-1', 'org.kde.kglobalaccel', 'org.freedesktop.FileManager1', 'org.kde.kwalletd5', 'org.PulseAudio1', 'org.kde.polkit-kde-authentication-agent-1', ':1.93', 'org.kde.kded5', 'org.kde.ActivityManager', 'org.kde.keyboard', 'org.kde.kate-3030', ':1.31', 'org.kde.kuiserver', ':1.32', ':1.55', ':1.33', ':1.11', 'org.kde.kwin.Screenshot', ':1.56', ':1.34', 'org.kde.StatusNotifierWatcher', 'org.kde.JobViewServer', ':1.35', ':1.0', ':1.13', ':1.58', 'org.kde.StatusNotifierHost-616', ':1.14', ':1.59', ':1.15', ':1.38', ':1.16', 'org.kde.ksmserver', ':1.39', ':1.17', ':1.5', 'org.kde.Solid.PowerManagement.PolicyAgent', ':1.18', 'org.kde.klauncher', ':1.6', ':1.19']
The following example makes your system hibernate:
# Get the power management object
power = bus.get('org.gnome.PowerManager', '/org/gnome/PowerManager')
# Hibernate the system
if power.CanHibernate():
power.Hibernate()