4. Graphical Access and X-Windows: XFree86, eXceed

X-Windows is the foundation (protocol) upon which most GUIs on Unix boxes are based. As you would expect processes (applications) running on the local machine can display in a window (or windows) on the local screen. In addition processes running on a remote machine can display on the local box --- to achieve this an X-server must be running on both machines. Thus X-Windows can be used to have processes which are running on Cosmos, for example an xterm, an editor and an image-viewer, all display on the local desktop/screen.

X-servers are also available for MS Windows. X-clients --- processes displaying a window on the desktop, whether on the machine local to the process or on a remote machine --- can display their windows on the MS Windows desktop in one of two modes (see below).

4.1. An Introduction to Using X-Windows

An excellent introduction to using X-Windows is available in PDF from www.rice.edu.

4.2. XFree86

Most Linux distributions (and other free Unices) come with XFree86, a free, open-source version of X-Windows. Usually a remote process (e.g., on Cosmos) will display in its own window on a Linux machine's desktop.

A port of XFree86 to MS Windows has been part of CygWin for some time now. When XFree86 is started a single large window is started on the MS Windows desktop --- this is the X-desktop. All X-clients display their windows within this one large window. Usually a local window-manager (e.g., TWM) or environment (such as KDE with its window-manager, KWM) manages this X-desktop.

4.3. eXceed

eXceed is a commercial X-server for MS Windows machines --- UMIST has a site license for this software. eXceed has two major modes: it may be configured to start one large window within which all X-clients display their windows (this will allow a remote machine, e.g., Cosmos, to manage your local X-desktop) or, more usually, eXceed has X-clients display their windows directly on the MS Windows desktop. (This second mode is usually faster.)