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

• dasbus is a Python3-only alternative to pydbus with additional features and better flexibility

• 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())

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())

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()

dasbus

For more information see dasbus's documentation.

Introspection of a remote object

Introspection returns an XML string containing information about interfaces, methods, properties and signals of the remote object.

from dasbus.connection import SessionMessageBus
bus = SessionMessageBus()

# Create an object that will be a proxy for a particular remote object.
remote_object = bus.get_proxy(
    "org.freedesktop.DBus",  # The bus name
    "/org/freedesktop/DBus"  # The object path
)

# Call the Introspect method of the remote object.
print(remote_object.Introspect())

Accessing a remote property

The following example prints the current hostname.

from dasbus.connection import SystemMessageBus
bus = SystemMessageBus()

proxy = bus.get_proxy(
    "org.freedesktop.hostname1",
    "/org/freedesktop/hostname1"
)

print(proxy.Hostname)

Calling a remote method

The following example sends a notification to the notification server.

from dasbus.connection import SessionMessageBus
bus = SessionMessageBus()

proxy = bus.get_proxy(
    "org.freedesktop.Notifications",
    "/org/freedesktop/Notifications"
)

id = proxy.Notify(
    "", 0, "face-smile", "My notification",
    "Hello World!", [], {}, 0
)

print("The notification {} was sent.".format(id))