Introduction to the Unix Cluster. Node: Anatomy
The architecture of the X Window System is based on what's known
as the client-server model. X consists of three parts:
X Display Server - a program that keeps track of all input coming
from input devices (such as the keyboard and mouse), input from any
other clients that are running, and provides display capabilities. As
the server receives information from a client, it updates the
appropriate window on your screen. The display server keeps track of the
hardware, may run on the same computer as a client or on an entirely
different machine, and is the only part of X that must be
Clients - application programs that perform specific tasks. These
tasks can include keeping track of incoming mail (xbiff), terminal
emulation (xterm), and even providing an on-line manual for X (xman).
Very importantly, since clients need not be machine-specific (only the
server interacts directly with the hardware), they can be ported easily
from system to system.
Window Manager - a program that handles negotiations between the
different clients as they fight for screen space, colors, and sunlight.
The window manager used at PPPL is twm, which is shipped with the
standard release of X from MIT. It's the window manager that controls
the moving of windows, converting windows to icons and back, and a large
variety of other tasks. When you start up X-Windows, a file in your home
directory known as `
~/.twmrc' (See Customizing.) will be read to set up the look-and-feel of your screen.