X Protocol

The X Protocol (sometimes referred to as X or X11) is a display protocol developed in the 1980's primarily to support UNIX graphics. X provides for the display and management of graphical information. X is based on a client-server model. The X Server program runs on a computer with a graphical display and handles communication with other client applications. The server handles request for displaying information as well as returning input received from the user such as keyboard or mouse input. The X Client is the application that is running and performing the computational work. It makes requests to the server for windows to be drawn, closed, etc. Note, this is confusing towards the traditional line of client-server thought however, X labels servers and clients from the viewpoint of the application as opposed to you, the user.

X is network transparent which means it does not care whether the server is running on the same machine as the client or some other machine. This is very helpful as various computer architectures and operating systems could access the same software remotely. This portability ensures a common look and feel for an application regardless of where it is accessed. In addition, applications themselves don't suffer a performance penalty for having to display the information. The performance factor come in the communcation method between X server and X client. If the X server and X client are communicating over a dial up internet connection - application could appear to run extremely slow. For this to work effectively over the internet - the client and server should communicate securely via a tunnel (see SSH).

X is direly important here on campus, considering parts of VCL, as well as almost every remote application depends on it. Once again, all that is required to take part of this power is having an X interpreter installed locally. NC State provides a X client for your use, a program we will be using very often in this class: X-Win 32