I am working on an app that is able to remotely lock the screen of a user. case: you forgot to lock your desktop when you went for lunch/coffee and want to make sure your laptop is locked.
Different desktop environments have different service names to lock the screen:
on KDE: org.kde.screensaver
on Unity and GNOME: org.gnome.ScreenSaver
on KDE and GNOME: /ScreenSaver
on Unity: /com/canonical/Unity/Session
The dbus interfaces are:
I put more organized info here: https://github.com/om26er/linux-desktop-manager/blob/bf55285ef88fdc49f49d238d67bcc4a841e6fefd/ldm/manager.py#L3