Understanding the X Window System Protocol

The Linux desktop environment, the X Window System, functions differently from the desktop environments of other operating systems, such as Microsoft Windows. X Window System applications rely on a network protocol to connect to the display on which they appear instead of drawing to the computer display directly. Figure 27.1 illustrates this concept.

Figure 27.1. X Window System applications communicate with the desktop using a network protocol instead of drawing directly. Thus, applications need not run on the machine where they are displayed.

Although the network-oriented nature of the X Window System adds complexity to the desktop environment, it provides a native capability not available in any other operating system's desktop environment. You have the ability to run a program on one machine's processor while displaying the application window on another machine's desktop, automatically using the network for communication between the two. Using this technique, a system administrator working at a Linux computer can start and interact with application windows whose programs are actually running on one or more machines elsewhere on the network.

Simple examples of the uses for the networking capabilities of the X Window System include the following:

• Starting xload or other monitoring applications on multiple machines around the network but displaying them all on a single computer's desktop. This allows the load or status of a number of different Linux or Unix systems to be monitored graphically from a single location.

• Running graphical administration tools for remote systems from a central location. Instead of having to walk from computer to computer, an experienced Linux administrator can manage every Linux or Unix system on the network without ever leaving his or her workstation.

• Creating graphical dumb terminals. These computers have little processing power or storage, but instead run only the X Window System and can thus use the storage and processing power of another, more powerful Linux or Unix computer to provide applications and a complete desktop environment.

With the networking capabilities of the X Window System, the sky and your creativity are your only limits.