Xdmx
Encyclopedia
Xdmx or DMX is the Distributed Multihead X Project. It acts as a proxy X
server for multiple back-end X servers. When combined with Xinerama
support, the multiple displays handled by DMX are presented to the user as a single unified screen.
For example, DMX could provide multi monitor
support using two desktop computers, each of which has a single monitor. Or, it could unify a 4 by 4 grid of monitors between 8 computers each with 2 monitors attached to them.
DMX was developed and runs under Linux
. In addition, DMX has been reported to work under most X11 architectures such as X11 running under Mac OS
.
A common misconception about DMX is that it is a window manager
. DMX is not a window manager, but another X server. As a result a window manager such as KWin
, Metacity
, Fluxbox
, etc. is needed to run on top of DMX for maximum usage. The DMX server is known as the front-end X server, while the servers that the DMX server connects to are known as the back-end servers. X clients can use the DMX server just like a normal X server, while the DMX server uses the back-end servers to actually do the drawing.
DMX implements the GLX
protocol for indirect rendering. This allows clients to use OpenGL
for 3D graphics on a distributed
display. This feature is known as GLX proxy. However, GLX proxy has a number of issues. Including:
Because of the above limitations, many users use Chromium for OpenGL support when using DMX. Using the
tilesort SPU, Chromium can provide 3d acceleration over the entire DMX display (consisting of multiple machines). In addition, Chromium can be configured to use the dmxdirect SPU to provide near native 3D rendering capabilities by limiting 3D rendering to only a single back-end display.
X Window System
The X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers...
server for multiple back-end X servers. When combined with Xinerama
Xinerama
Xinerama is an extension to the X Window System which enables multi-headed X applications and window managers to use two or more physical displays as one large virtual display.It was originally developed by Madeline T...
support, the multiple displays handled by DMX are presented to the user as a single unified screen.
For example, DMX could provide multi monitor
Multi monitor
Multi-Monitor, also called Multi-Display and Multi-Head, is the use of multiple physical display devices, such as monitors, televisions, and projectors, in order to increase the area available for computer programs running on a single computer system...
support using two desktop computers, each of which has a single monitor. Or, it could unify a 4 by 4 grid of monitors between 8 computers each with 2 monitors attached to them.
DMX was developed and runs under Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
. In addition, DMX has been reported to work under most X11 architectures such as X11 running under Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
.
A common misconception about DMX is that it is a window manager
Window manager
A window manager is system software that controls the placement and appearance of windows within a windowing system in a graphical user interface. Most window managers are designed to help provide a desktop environment...
. DMX is not a window manager, but another X server. As a result a window manager such as KWin
KWin
KWin is a window manager for the X Window System. It is an integral part of the KDE Software Compilation, although it can be used on its own or with other desktop environments.- History :- Look and feel :...
, Metacity
Metacity
Metacity was the window manager used by default in the GNOME desktop environment until GNOME 3, where it was replaced by Mutter. The development of Metacity was started by Havoc Pennington and it is released under the GNU General Public License....
, Fluxbox
Fluxbox
Fluxbox is a stacking window manager for the X Window System, which started as a fork of Blackbox 0.61.1, with the same aim to be lightweight. Its user interface has only a taskbar, a pop-up menu accessible by right-clicking on the desktop, and minimal support for graphical icons...
, etc. is needed to run on top of DMX for maximum usage. The DMX server is known as the front-end X server, while the servers that the DMX server connects to are known as the back-end servers. X clients can use the DMX server just like a normal X server, while the DMX server uses the back-end servers to actually do the drawing.
DMX implements the GLX
GLX
GLX provides the interface connecting OpenGL and the X Window System: it enables programs wishing to use OpenGL to do so within a window provided by the X Window System.-History:...
protocol for indirect rendering. This allows clients to use OpenGL
OpenGL
OpenGL is a standard specification defining a cross-language, cross-platform API for writing applications that produce 2D and 3D computer graphics. The interface consists of over 250 different function calls which can be used to draw complex three-dimensional scenes from simple primitives. OpenGL...
for 3D graphics on a distributed
display. This feature is known as GLX proxy. However, GLX proxy has a number of issues. Including:
- It requires homogeneous GLX visuals on the back-end displays. This often causes problems for people who are mixing back-end machines with differing 3D capabilities. For example, it would likely not work if one back-end used an ATIATI TechnologiesATI Technologies Inc. was a semiconductor technology corporation based in Markham, Ontario, Canada, that specialized in the development of graphics processing units and chipsets. Founded in 1985 as Array Technologies Inc., the company was listed publicly in 1993 and was acquired by Advanced Micro...
graphics card and another a nVidiaNVIDIANvidia is an American global technology company based in Santa Clara, California. Nvidia is best known for its graphics processors . Nvidia and chief rival AMD Graphics Techonologies have dominated the high performance GPU market, pushing other manufacturers to smaller, niche roles...
card. - It has limited support for newer versions of OpenGL and lacks support for most modern OpenGL extensions.
- It is not compatible with dynamic screen addition and removal.
- Indirect Rendering is almost always slower than direct rendering.
Because of the above limitations, many users use Chromium for OpenGL support when using DMX. Using the
tilesort SPU, Chromium can provide 3d acceleration over the entire DMX display (consisting of multiple machines). In addition, Chromium can be configured to use the dmxdirect SPU to provide near native 3D rendering capabilities by limiting 3D rendering to only a single back-end display.
External links
- Distributed Multihead X Project (Official Website)
- IBM Developerworks Tutorial for Xdmx