X Window System: Encyclopedia II - X Window System - Implementations

X Window System - Implementations

The X.Org reference implementation serves as the canonical implementation of X. Due to the liberal licensing, a number of variations, both free and proprietary, have appeared. Commercial UNIX vendors have tended to take the reference implementation and adapt it for their hardware, usually customising it heavily and adding proprietary extensions.

Up to 2004, XFree86 provided the most common X variant on free Unix-like systems. XFree86 started as a port of X for 386-compatible PCs and, by the end of the 1990s, had become the greatest source of technical innovation in X and the de facto steward of X development [2]. As of 2004, the most popular X server is the current X.Org reference implementation, a fork of XFree86.

While computer aficionados most often associate X with Unix, X servers also exist natively within other graphical environments. Hewlett-Packard's OpenVMS operating system includes a version of X with CDE, known as DECwindows, as its standard desktop environment. Apple's Mac OS X v10.3 (Panther) includes X11.app, based on XFree86 4.3 and X11R6.6, with better Mac OS X integration. Third-party servers under Macintosh System 7, 8 and 9 included MacX.

Microsoft Windows does not come with support for X, but many third-party implementations exist, both free software such as Cygwin/X, Xming, WeirdMind and WeirdX; and proprietary products such as Xmanager, WiredX, Exceed and X-Win32. They normally serve to control remote X clients.

When X is hosted on another windowing system (such as those of Microsoft Windows or Mac OS) the X system is generally "rootless", meaning the host windowing environment is responsible for the root window (the background and associated menus) and for managing the geometry of the hosted X windows — although some servers, such as Exceed, can also create the root window for the remote clients to display to as a separate window in the host system.

X Window System - X terminals

An X terminal consists of a piece of dedicated hardware running an X server as a thin client. This architecture became popular for building inexpensive terminal parks for many users to simultaneously use the same large server. This use very much aligns with the original intention of the MIT project.

X terminals can explore the network (the local broadcast domain) using the X Display Manager Control Protocol to generate a list of available hosts that they can run clients from. The initial host needs to run an X display manager.

Dedicated (hardware) X terminals have become less common; a PC with an X server typically provides the same functionality at a lower cost.

Adapted from the Wikipedia article "Implementations", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki