samples-dbus

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#+TITLE: A sample code illustrating basic use of D-BUS

• Introduction

This sample code illustrates how to get DBUS communication up and running by providing a minimalistic client server application based on the (low-level) dbus library /libdbus/ and also on GLib wrapper library /GDBus/.

/libdbus/ is the library provided by D-Bus itself, and exposes a low-level API.

/GDBus/ is the support of D-Bus in /GLib/ since 2.26. It simplifies the details of D-Bus programming is intended to replace the DBus-GLib bindings. It provides a [[https://developer.gnome.org/gio/2.26/gdbus-convenience.html][high-level]] and a [[https://developer.gnome.org/gio/2.26/gdbus-lowlevel.html][low-level]] APIs.

• Server

The server exports a single object, which can be reached at /org/example/TestObject.

This object implements the /org.example.TestInterface/ which provides a couple of basic services/methods: Ping, Echo, EmitSignal and Quit.

TestObject also implements both /org.freedesktop.DBus.Introspectable/ interface which allows object instrospection. Therefore a client or a D-Bus debugger tool, such as d-feet(1), can inspect and list the interfaces, methods, and signals of our object by using those interfaces.

The server code uses the low-level API provided by /libdbus/, except for the event loop which is provided by GLib for the sake of simplicity.

• Client

The client is an application which runs unit tests: it connects to the server and calls all services provided by the server and check their result.

Unlike the server, the client relies on /GDBus/ library using both the high-level and low-level APIs. The other GLib wrapper library /dbus-glib/ is obsolete and shouldn't be used in new application.

Its main purpose is to show how to call methods on a remote object using a proxy object and how to listen a signal.

• Installation

The followng dependencies are required in order to build successfully this project:

• libdbus (server)
• dbus-glib (server event loop)
• glib (client)

To generate server and client binaries, running 'make' should be fine. It will generate two binaries: /dbus-client/ and /dbus-server/.