Overview
D-Bus is an inter-process communication (IPC) mechanism initially designed to replace the software component communications systems used by the GNOME and KDE Linux desktop environments.
Due to the large number of processes involved - adding up processes providing the services and clients accessing them - establishing one-to-one IPC communications between all of them becomes an inefficient and quite unreliable approach. Instead, D-Bus provides a software-bus abstraction that gathers all the communications between a group of processes over a single shared virtual channel.
Processes connected to a bus don’t know how it is internally implemented, but D-Bus specification guarantees that all processes connected to the bus can communicate with each other through it.
Linux desktop environments take advantage of the D-Bus facilities by instantiating multiple buses, notably:
- a single system bus, available to all users and processes of the system, that provides access to system services (i.e. services provided by the operating system and also by any system daemons)
- a session bus for each user login session, that provides desktop services to user applications in the same desktop session, and allows the integration of the desktop session as a whole.
D-Bus provides additional or simplifies existing functionality to the applications, including information-sharing, modularity and privilege separation.