The client–server model is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients. Often clients and servers communicate over a computer network on separate hardware, but both client and server may reside in the same system. A server host runs one or more server programs, which share their resources with clients. A client usually does not share any of its resources, but it requests content or service from a server. Clients, therefore, initiate communication sessions with servers, which await incoming requests. Examples of computer applications that use the client–server model are email, network printing, and the World Wide Web.
A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterprise resource planning, and large-scale transaction processing. A mainframe computer is large but not as large as a supercomputer and has more processing power than some other classes of computers, such as minicomputers, servers, workstations, and personal computers. Most large-scale computer-system architectures were established in the 1960s, but they continue to evolve. Mainframe computers are often used as servers.
In computer networking, a thin client is a simple (low-performance) computer that has been optimized for establishing a remote connection with a server-based computing environment. They are sometimes known as network computers, or in their simplest form as zero clients. The server does most of the work, which can include launching software programs, performing calculations, and storing data. This contrasts with a rich client or a conventional personal computer; the former is also intended for working in a client–server model but has significant local processing power, while the latter aims to perform its function mostly locally.
The X Window System is a windowing system for bitmap displays, common on Unix-like operating systems.
Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems (Sun) in 1984, allowing a user on a client computer to access files over a computer network much like local storage is accessed. NFS, like many other protocols, builds on the Open Network Computing Remote Procedure Call system. NFS is an open IETF standard defined in a Request for Comments (RFC), allowing anyone to implement the protocol.
A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has been used loosely to refer to everything from a mainframe computer terminal to a PC connected to a network, but the most common form refers to the class of hardware offered by several current and defunct companies such as Sun Microsystems, Silicon Graphics, Apollo Computer, DEC, HP, NeXT, and IBM which powered the 3D computer graphics revolution of the late 1990s.
Systems Network Architecture (SNA) is IBM's proprietary networking architecture, created in 1974. It is a complete protocol stack for interconnecting computers and their resources. SNA describes formats and protocols but, in itself, is not a piece of software. The implementation of SNA takes the form of various communications packages, most notably Virtual Telecommunications Access Method (VTAM), the mainframe software package for SNA communications.
In computing, a windowing system is a software suite that manages separately different parts of display screens. It is a type of graphical user interface (GUI) which implements the WIMP paradigm for a user interface.
A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. The teletype was an example of an early-day hard-copy terminal and predated the use of a computer screen by decades. Starting in the mid-1970s with machines such as the Sphere 1, Sol-20, and Apple I, terminal circuitry began to be integrated into personal and workstation computer systems, with the computer handling character generation and outputting to a CRT display such as a computer monitor or, sometimes, a consumer TV.
Project Athena was a joint project of MIT, Digital Equipment Corporation, and IBM to produce a campus-wide distributed computing environment for educational use. It was launched in 1983, and research and development ran until June 30, 1991. As of 2023, Athena is still in production use at MIT. It works as software that makes a machine a thin client, that will download educational applications from the MIT servers on demand.
Linux Terminal Server Project (LTSP) is a free and open-source terminal server for Linux that allows many people to simultaneously use the same computer. Applications run on the server with a terminal known as a thin client handling input and output. Generally, terminals are low-powered, lack a hard disk and are quieter and more reliable than desktop computers because they do not have any moving parts.
A diskless node is a workstation or personal computer without disk drives, which employs network booting to load its operating system from a server.
In computing, the X Window System is a network-transparent windowing system for bitmap displays. This article details the protocols and technical structure of X11.
Desktop virtualization is a software technology that separates the desktop environment and associated application software from the physical client device that is used to access it.
Network Computing Devices (NCD) was a company founded in 1987 to produce a new class of products now known as a thin client. It was founded in Mountain View, CA, and when it closed it was headquartered in Beaverton, Oregon.
Adaptive Internet Protocol (AIP) is a multi-channel protocol that allows an application running on any of multiple platforms to be displayed on any of a wide range of client systems. It supports rich remote display and input services with a number of display options to deliver the presentation of the remote applications onto the local display either as a standalone window, or within a contained remote environment delivered full-screen or in a standalone window. The protocol also supports audio, printing, and other device mapping services.
Pano Logic was a manufacturer of devices which present virtual desktops to the end user with no local processing power. They describe this concept as "zero client". This is perceived as offering benefits in end-user support and in power provision to desks. OEM versions have been included in displays from some vendors, allowing a single unit to be deployed. The company failed in October 2012. In March 2013, Propalms announced they had acquired the rights to support Panologic customers, and will "help transition the customer base to a new platform".
Wyse Technology, often shortened to Wyse, was an independent American manufacturer of cloud computing systems. As of 2012, Wyse is a subsidiary of Dell. Wyse are best remembered for their video terminal line introduced in the 1980s, which competed with the market-leading Digital. They also had a successful line of IBM PC compatible workstations in the mid-to-late 1980s. But starting late in the decade, Wyse were outcompeted by companies such as eventual parent Dell. Current products include thin client hardware and software as well as desktop virtualization solutions. Other products include cloud software-supporting desktop computers, laptops, and mobile devices. Dell Cloud Client Computing is partnered with IT vendors such as Citrix, IBM, Microsoft, and VMware.
Computers can be classified, or typed, in many ways. Some common classifications of computers are given below.
Visionware Ltd was a British software company that developed and marketed products that helped integration of Microsoft Windows clients to Unix-based server applications. It was based in Leeds in West Yorkshire. The three products it was most known for were PC-Connect, XVision, and SQL-Retriever.
