The Nemo Mobile D-Bus QML Plugin allows you to access services on the system and session bus, as well as provide your own services. D-Bus is used for interprocess communication. Several system services expose an interface over D-Bus that can be used by third party software and other middleware.
D-Bus is a message bus system, a simple way for applications to talk to one another. In addition to interprocess communication, D-Bus helps coordinate process lifecycle; it makes it simple and reliable to code a "single instance" application or daemon, and to launch applications and daemons on demand when their services are needed. (from the D-Bus homepage)