Before you begin administering and customizing the Graphical Environment, you should familiarize yourself with the concepts of X servers and X clients.
The ``X server'' is the software that controls a workstation's or X terminal's hardware, such as its physical display, the keyboard, and mouse or other pointer device. It relays messages between X clients and the hardware on which the clients run. When you use the mouse, keyboard, or a drawing pad to interact with a client, the client decides how to respond to the input (for example, redraw a window, open a menu, and so forth). The client then sends a message to the server, asking for the appropriate action to take place. In response, the server interacts with the system's graphics adapter, whereby the appropriate output is displayed on your screen.
It is the server that actually creates windows and draws images and text in them, in response to requests from client programs. The X server does not initiate actions itself; it only performs actions that are requested by client processes.
The SCO OpenServer Graphical Environment uses the industry-standard X Window System server.
An ``X client'' is a program or application that is written specifically for the X Window System, using X programming tools. These programs are called clients because they act as customers of the X server, asking the server to perform particular actions on their behalf. Clients cannot affect a window or display directly; they can only send a request to the X server to do what they require.
Two major clients of the Graphical Environment are the SCO® Panner window manager (an enhanced version of the OSF/Motif® window manager) and the Desktop.
The Graphical Environment uses the client-server architecture because it allows each client to be hardware-independent. This way, clients are more easily ported to different hardware and operating system platforms, and users can access clients that reside on other machines.