DBus

DBus is a message bus system that provides a communication mechanism between multiple applications running on the same machine. It was developed as part of the freedesktop.org project to standardize inter-process communication in Linux and Unix-like operating systems.

The system consists of two primary bus types: the system bus and the session bus. The system bus handles communication between system services and privileged processes, while the session bus manages communication between user applications within a specific login session. Applications can send messages to specific services or broadcast signals that other applications can subscribe to receive.

DBus operates using a client-server architecture where applications connect to a central daemon process. Messages are transmitted in a binary format and can contain various data types including integers, strings, arrays, and complex nested structures. The protocol supports both method calls, which expect responses, and signals, which are one-way notifications.

Services on DBus are identified by unique names following a reverse domain name convention, such as org.freedesktop.NetworkManager. Each service can expose objects with specific interfaces that define the methods and signals available for communication. This object-oriented approach allows for organized and structured inter-process communication.

The technology is widely used in modern Linux desktop environments including GNOME, KDE, and systemd. Common applications include network management, power management, desktop notifications, and system monitoring tools. Many programming languages provide bindings for DBus, making it accessible to developers working in C, Python, Java, and other languages.

DBus has largely replaced older inter-process communication mechanisms like CORBA in the Linux ecosystem. While it was originally designed for desktop environments, its use has expanded to server applications and embedded systems where reliable process communication is required.