Understanding X Window System and Desktop Environment of Linux

In this post I will try to explain you how a Linux Desktop Environment works, and I hope after going through this post you will have a batter understanding of the mechanism used by the Linux Systems.

To achieve a full fledge Desktop, Linux systems use following  major components :

1)    X Windowing System
2)    A Desktop Manager
3)    A Windowing Manager

Now lets have a step by step look on each of the above components.

X window System :

X window system (also know as X) was developed in 1980s at MIT by researchers working on a distributed computing project , and was the first windowing system for UNIX that was widely adopted and accepted. X window system was built to work over the network where other computers can communicate with each other and remote applications can receive and send information to other client applications on the network using X protocols .

Initially X was deployed on high end machines used for scientific purposes and computing. But later in 1990s when the prices of computing equipment were dropped X was customized to run on lower end and inexpensive PCs, and the project was named as Xfree86.
Xfree86 was used by many Linux distributions , But due to some license issues in 2004 Xfree86 was abandoned and was replaced by X.org a decedent of Xfree86 .

The Components of X :

Xserver : Xserver runs on the users local machine and is responsible for providing services to the client programs such as drawing graphics,passing keyboard and mouse events etc.

Xclient : Xclient is any application or program that depends on X windowing system and uses services provided by the Xserver . For example a text-processing Xclient will get its input from the keyboard events passed by the Xserver to it.

Xprotocols : Xprotocols provide a mean of communication between Xserver and Xclient .

Xlib : Xlib is low level and very complicated library on which Xclients depends for relaying protocol massages to the Xserver.

Desktop manager :

Desktop manager provides a unified mechanism through witch many Xclients can run to build a common user interface (GUI). Desktop manager in general includes a whole set of functionalities for maintaining a Desktop Environment in which users can launch and run other applications to accomplish their tasks with ease such as running multiple applications,managing files using built-in file managers, browsing the web, printing ,graphics designing,running multimedia applications etc.
some of the most popular Desktop managers are: Gnome , KDE and Xfce.

Windowing Manger :

Where a Desktop manager provides all the above mentioned functionalities and facilities, a window manager handles the behavior of graphical windows on the screen such as drag and drop , moving and resizing,  window borders , title bars and other customized behaviors specified by the user.
Some examples of windows managers are : metacity (Gnome) ,Kwin (KDE) ,Sawfish etc.

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