How KDE Plasma 5 Optionally Uses systemd

For those wondering how KDE Plasma 5 -- and other desktop environments -- have come to begin utilizing systemd,
David Edmundson has a great blog post covering the details about the various components of systemd used by KDE Plasma.

While systemd is an init system, its continuously expanding set of features have become of interest to KDE and GNOME developers, among other desktop environments. Most widely used is systemd's logind component by various desktops for keeping track of seats/sessions and device management while allowing the X.Org Server to run without root privileges. KDE Plasma 5 also relies upon systemd's logind for inhibitor locks.

Another systemd component that can be used by Plasma 5 is timedated and its other daemons for allowing basic system admin tasks like time adjustment, locale management, managing the hostname, etc, through DBus interfaces.

Going forward, KDE developers may look at making greater use of systemd user units, potentially replacing parts of the KDE daemon with systemd directly for managing services.

The systemd usage in KDE Plasma isn't yet mandated given that some platforms (particularly the BSDs) lack systemd and that alternatives for implementing these interfaces are still maturing.

More details about the KDE Plasma + systemd usage can be found via Edmundson's blog.