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45-400: X386 was an implementation of the X Window System for IBM PC compatible computers. It ran on systems with Intel 386 or later processors, running Unix System V -based operating systems , and supported a variety of VGA -compatible graphics cards . X386 was created by Thomas Roell while at Technische Universität München and first released (as X386 1.1, based on X11R4 ) in 1991. X386 1.2

90-476: A computer somewhere on a network (such as the Internet) can display its user interface on an X server running on some other computer on the network. The X server is typically the provider of graphics resources and keyboard/mouse events to X clients , meaning that the X server is usually running on the computer in front of a human user, while the X client applications run anywhere on the network and communicate with

135-508: A desktop environment, which, aside from the window manager, includes various applications using a consistent user interface. Popular desktop environments include GNOME , KDE Plasma and Xfce . The UNIX 98 standard environment is the Common Desktop Environment (CDE). The freedesktop.org initiative addresses interoperability between desktops and the components needed for a competitive X desktop. The X.Org implementation

180-741: A functional form of the "network transparency" feature of X, via network transmissibility of graphical services, include: Several bitmap display systems preceded X. From Xerox came the Alto (1973) and the Star (1981). From Apollo Computer came Display Manager (1981). From Apple came the Lisa (1983) and the Macintosh (1984). The Unix world had the Andrew Project (1982) and Rob Pike 's Blit terminal (1982). Carnegie Mellon University produced

225-473: A native windowing system hosts X in addition, the X system can either use its own normal desktop in a separate host window or it can run rootless , meaning the X desktop is hidden and the host windowing environment manages the geometry and appearance of the hosted X windows within the host screen. An X terminal is a thin client that only runs an X server. This architecture became popular for building inexpensive terminal parks for many users to simultaneously use

270-613: A network protocol supporting terminal and graphics windows, the server maintaining display lists. The email in which X was introduced to the Project Athena community at MIT in June 1984 The original idea of X emerged at MIT in 1984 as a collaboration between Jim Gettys (of Project Athena ) and Bob Scheifler (of the MIT Laboratory for Computer Science ). Scheifler needed a usable display environment for debugging

315-419: A port of X to 386-compatible PCs and, by the end of the 1990s, had become the greatest source of technical innovation in X and the de facto standard of X development. Since 2004, however, the X.Org Server, a fork of XFree86, has become predominant. While it is common to associate X with Unix, X servers also exist natively within other graphical environments. VMS Software Inc.'s OpenVMS operating system includes

360-730: A protocol that could both run local applications and call on remote resources. In mid-1983 an initial port of W to Unix ran at one-fifth of its speed under V; in May 1984, Scheifler replaced the synchronous protocol of W with an asynchronous protocol and the display lists with immediate mode graphics to make X version 1. X became the first windowing system environment to offer true hardware independence and vendor independence. Scheifler, Gettys and Ron Newman set to work and X progressed rapidly. They released Version 6 in January 1985. DEC, then preparing to release its first Ultrix workstation, judged X

405-784: A remote machine, the user may do the following: The remote X client application will then make a connection to the user's local X server, providing display and input to the user. Alternatively, the local machine may run a small program that connects to the remote machine and starts the client application. Practical examples of remote clients include: X primarily defines protocol and graphics primitives – it deliberately contains no specification for application user-interface design, such as button, menu, or window title-bar styles. Instead, application software – such as window managers, GUI widget toolkits and desktop environments, or application-specific graphical user interfaces – define and provide such details. As

450-544: A remote-access application called Alto Terminal, that displayed overlapping windows on the Xerox Alto, and made remote hosts (typically DEC VAX systems running Unix) responsible for handling window-exposure events and refreshing window contents as necessary. X derives its name as a successor to a pre-1983 window system called W (the letter preceding X in the English alphabet ). W ran under the V operating system . W used

495-567: A result, there is no typical X interface and several different desktop environments have become popular among users. A window manager controls the placement and appearance of application windows. This may result in desktop interfaces reminiscent of those of Microsoft Windows or of the Apple Macintosh (examples include GNOME 2, KDE Plasma, Xfce) or have radically different controls (such as a tiling window manager, like wmii or Ratpoison ). Some interfaces such as Sugar or ChromeOS eschew

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540-457: A specification for client interoperability, has a reputation for being difficult to implement correctly. Further standards efforts such as Motif and CDE did not alleviate problems. This has frustrated users and programmers. Graphics programmers now generally address consistency of application look and feel and communication by coding to a specific desktop environment or to a specific widget toolkit, which also avoids having to deal directly with

585-454: A task is independent both of locations of the data, and of the system on which an operation is carried out. Naming transparency means that a unique name is provided for each object in the database. Transparency in firewall technology can be defined at the networking (IP or Internet layer ) or at the application layer . Transparency at the IP layer means the client targets the real IP address of

630-473: A version of X with Common Desktop Environment (CDE), known as DECwindows, as its standard desktop environment. Apple originally ported X to macOS in the form of X11.app, but that has been deprecated in favor of the XQuartz implementation. Third-party servers under Apple's older operating systems in the 1990s, System 7, and Mac OS 8 and 9, included Apple's MacX and White Pine Software's eXodus. Microsoft Windows

675-414: Is a complete, albeit simple, display and interface solution which delivers a standard toolkit and protocol stack for building graphical user interfaces on most Unix-like operating systems and OpenVMS , and has been ported to many other contemporary general purpose operating systems . X provides the basic framework , or primitives, for building such GUI environments: drawing and moving windows on

720-407: Is generally not possible. However, approaches like Virtual Network Computing (VNC), NX and Xpra allow a virtual session to be reached from different X servers (in a manner similar to GNU Screen in relation to terminals), and other applications and toolkits provide related facilities. Workarounds like x11vnc ( VNC :0 viewers ), Xpra's shadow mode and NX's nxagent shadow mode also exist to make

765-524: Is no accessibility standard or accessibility guidelines for X11. Within the X11 standards process there is no working group on accessibility; however, accessibility needs are being addressed by software projects to provide these features on top of X. The Orca project adds accessibility support to the X Window System, including implementing an API ( AT-SPI ). This is coupled with GNOME's ATK to allow for accessibility features to be implemented in X programs using

810-492: Is not shipped with support for X, but many third-party implementations exist, as free and open source software such as Cygwin/X , and proprietary products such as Exceed, MKS X/Server, Reflection X, X-Win32 and Xming . There are also Java implementations of X servers. WeirdX runs on any platform supporting Swing 1.1, and will run as an applet within most browsers. The Android X Server is an open source Java implementation that runs on Android devices. When an operating system with

855-419: Is that they are not capable of any input or output other than the keyboard, mouse, and display. All relevant data is assumed to exist solely on the remote server, and the X terminal user has no methods available to save or load data from a local peripheral device. Dedicated (hardware) X terminals have fallen out of use; a PC or modern thin client with an X server typically provides the same functionality at

900-414: Is the canonical implementation of X. Owing to liberal licensing, a number of variations, both free and open source and proprietary, have appeared. Commercial Unix vendors have tended to take the reference implementation and adapt it for their hardware, usually customizing it and adding proprietary extensions. Until 2004, XFree86 provided the most common X variant on free Unix-like systems. XFree86 started as

945-576: The display and interacting with a mouse, keyboard or touchscreen. X does not mandate the user interface ; individual client programs handle this. Programs may use X's graphical abilities with no user interface. As such, the visual styling of X-based environments varies greatly; different programs may present radically different interfaces. Unlike most earlier display protocols, X was specifically designed to be used over network connections rather than on an integral or attached display device. X features network transparency , which means an X program running on

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990-573: The Argus system. Project Athena (a joint project between DEC , MIT and IBM to provide easy access to computing resources for all students) needed a platform-independent graphics system to link together its heterogeneous multiple-vendor systems; the window system then under development in Carnegie Mellon University 's Andrew Project did not make licenses available, and no alternatives existed. The project solved this by creating

1035-549: The GNOME/GTK APIs. KDE provides a different set of accessibility software, including a text-to-speech converter and a screen magnifier. The other major desktops (LXDE, Xfce and Enlightenment) attempt to be compatible with ATK. An X client cannot generally be detached from one server and reattached to another unless its code specifically provides for it ( Emacs is one of the few common programs with this ability). As such, moving an entire session from one X server to another

1080-702: The ICCCM. X also lacks native support for user-defined stored procedures on the X server, in the manner of NeWS  – there is no Turing-complete scripting facility. Various desktop environments may thus offer their own (usually mutually incompatible) facilities. Systems built upon X may have accessibility issues that make utilization of a computer difficult for disabled users, including right click , double click , middle click , mouse-over , and focus stealing . Some X11 clients deal with accessibility issues better than others, so persons with accessibility problems are not locked out of using X11. However, there

1125-480: The X Window System are not capable of working over the network. In a centralized database system , the only available resource that needs to be shielded from the user is the data (that is, the storage system ). In a distributed DBMS , a second resource needs to be managed in much the same manner: the network . Preferably, the user should be protected from the network operational details. Then there would be no difference between database applications that would run on

1170-502: The X project, with the current reference implementation, X.Org Server , available as free and open-source software under the MIT License and similar permissive licenses. X is an architecture-independent system for remote graphical user interfaces and input device capabilities. Each person using a networked terminal has the ability to interact with the display with any type of user input device. In its standard distribution it

1215-578: The X server by a remote X client program, and each then rendered by sending a single glCallList(which) across the network. X provides no native support for audio; several projects exist to fill this niche, some also providing transparent network support. X uses a client–server model: an X server communicates with various client programs. The server accepts requests for graphical output (windows) and sends back user input (from keyboard, mouse, or touchscreen). The server may function as: This client–server terminology – the user's terminal being

1260-453: The bandwidth of a 100 Mbit/s network for a single client. In contrast, modern versions of X generally have extensions such as Mesa allowing local display of a local program's graphics to be optimized to bypass the network model and directly control the video card, for use of full-screen video, rendered 3D applications, and other such applications. X's design requires the clients and server to operate separately, and device independence and

1305-470: The centralized database and those that would run on a distributed one. This kind of transparency is referred to as network transparency or distribution transparency . From a database management system (DBMS) perspective, distribution transparency requires that users do not have to specify where data is located. Some have separated distribution transparency into location transparency and naming transparency. Location transparency in commands used to perform

1350-552: The client and server may run on the same machine or on different ones, possibly with different architectures and operating systems. A client and server can even communicate securely over the Internet by tunneling the connection over an encrypted network session. An X client itself may emulate an X server by providing display services to other clients. This is known as "X nesting". Open-source clients such as Xnest and Xephyr support such X nesting. To run an X client application on

1395-422: The client application uses the protocol in a different way. An example of a transparent HTTP request for a server: An example non-transparent HTTP request for a proxy (cache): Application layer transparency is symmetric when the same working mode is used on both the sides. The transparency is asymmetric when the firewall (usually a proxy) converts server type requests to proxy type or vice versa. Transparency at

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1440-426: The current X-server screen available. This ability allows the user interface (mouse, keyboard, monitor) of a running application to be switched from one location to another without stopping and restarting the application. Network traffic between an X server and remote X clients is not encrypted by default. An attacker with a packet sniffer can intercept it, making it possible to view anything displayed to or sent from

1485-454: The desktop metaphor altogether, simplifying their interfaces for specialized applications. Window managers range in sophistication and complexity from the bare-bones ( e.g. , twm, the basic window manager supplied with X, or evilwm, an extremely light window manager) to the more comprehensive desktop environments such as Enlightenment and even to application-specific window managers for vertical markets such as point-of-sale. Many users use X with

1530-568: The local X server to both local and remotely hosted X client programs who need to share the user's graphics and input devices to communicate with the user. X's network protocol is based on X command primitives. This approach allows both 2D and (through extensions like GLX) 3D operations by an X client application which might be running on a different computer to still be fully accelerated on the X server's display. For example, in classic OpenGL (before version 3.0), display lists containing large numbers of objects could be constructed and stored entirely in

1575-408: The only windowing system likely to become available in time. DEC engineers ported X6 to DEC's QVSS display on MicroVAX . Network transparency The term is often partially correctly applied in the context of the X Window System , which is able to transmit graphical data over the network and integrate it seamlessly with applications running and displaying locally; however, certain extensions of

1620-514: The proprietary SGCS version. This free and open-source software article is a stub . You can help Misplaced Pages by expanding it . X Window System The X Window System ( X11 , or simply X ; stylized 𝕏 ) is a windowing system for bitmap displays, common on Unix-like operating systems. X originated as part of Project Athena at Massachusetts Institute of Technology (MIT) in 1984. The X protocol has been at version 11 (hence "X11") since September 1987. The X.Org Foundation leads

1665-750: The same host. Additionally shared memory (via the MIT-SHM extension) can be employed for faster client–server communication. However, the programmer must still explicitly activate and use the shared memory extension. It is also necessary to provide fallback paths in order to stay compatible with older implementations, and in order to communicate with non-local X servers. Some people have attempted writing alternatives to and replacements for X. Historical alternatives include Sun 's NeWS and NeXT 's Display PostScript , both PostScript -based systems supporting user-definable display-side procedures, which X lacked. Current alternatives include: Additional ways to achieve

1710-517: The same large computer server to execute application programs as clients of each user's X terminal. This use is very much aligned with the original intention of the MIT project. X terminals explore the network (the local broadcast domain ) using the X Display Manager Control Protocol to generate a list of available hosts that are allowed as clients. One of the client hosts should run an X display manager . A limitation of X terminals and most thin clients

1755-476: The same, or lower, cost. The Unix-Haters Handbook (1994) devoted a full chapter to the problems of X. Why X Is Not Our Ideal Window System (1990) by Gajewska, Manasse and McCormack detailed problems in the protocol with recommendations for improvement. The lack of design guidelines in X has resulted in several vastly different interfaces, and in applications that have not always worked well together. The Inter-Client Communication Conventions Manual (ICCCM),

1800-487: The separation of client and server incur overhead. Most of the overhead comes from network round-trip delay time between client and server ( latency ) rather than from the protocol itself: the best solutions to performance issues depend on efficient application design. A common criticism of X is that its network features result in excessive complexity and decreased performance if only used locally. Modern X implementations use Unix domain sockets for efficient connections on

1845-428: The server and the applications being the clients – often confuses new X users, because the terms appear reversed. But X takes the perspective of the application, rather than that of the end-user: X provides display and I/O services to applications, so it is a server; applications use these services, thus they are clients. The communication protocol between server and client operates network-transparently:

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1890-415: The server. If a connection is non-transparent, then the client targets an intermediate host (address), which could be a proxy or a caching server. IP layer transparency could be also defined from the point of server's view. If the connection is transparent, the server sees the real client IP. If it is non-transparent, the server sees the IP of the intermediate host. Transparency at the application layer means

1935-471: The user's computer to request the rendering of graphics content and receive events from input devices including keyboards and mice. The fact that the term "server" is applied to the software in front of the user is often surprising to users accustomed to their programs being clients to services on remote computers. Here, rather than a remote database being the resource for a local app, the user's graphic display and input devices become resources made available by

1980-499: The user's screen. The most common way to encrypt X traffic is to establish a Secure Shell (SSH) tunnel for communication. Like all thin clients , when using X across a network, bandwidth limitations can impede the use of bitmap -intensive applications that require rapidly updating large portions of the screen with low latency, such as 3D animation or photo editing. Even a relatively small uncompressed 640×480×24 bit 30 fps video stream (~211 Mbit/s) can easily outstrip

2025-606: Was incorporated in the X11R5 release later the same year. Further X386 development was funded by Snitily Graphics Consulting Services, which released enhanced versions commercially. SGCS later became Xi Graphics and X386 evolved into the Accelerated-X product. In September 1992, the XFree86 project was created to continue development of X386 as open source software, the name being a pun on "X386", distinguishing it from

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