cyberorg012 / sample-dbus

a sample of dbus interface usage

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 high-level and a 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 The other GLib wrapper library dbus-glib is obsolete and shouldn’t be used in new application.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.