Centralized computing

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Centralized computing is computing done at a central location, using terminals that are attached to a central computer. The computer itself may control all the peripherals directly (if they are physically connected to the central computer), or they may be attached via a terminal server. Alternatively, if the terminals have the capability, they may be able to connect to the central computer over the network. The terminals may be text terminals or thin clients, for example.

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It offers greater security over decentralized systems because all of the processing is controlled in a central location. In addition, if one terminal breaks down, the user can simply go to another terminal and log in again, and all of their files will still be accessible. Depending on the system, they may even be able to resume their session from the point they were at before, as if nothing had happened.

This type of arrangement does have some disadvantages. The central computer performs the computing functions and controls the remote terminals. This type of system relies totally on the central computer. Should the central computer crash, the entire system will "go down" (i.e. will be unavailable).

Another disadvantage is that central computing relies heavily on the quality of administration and resources provided to its users. Should the central computer be inadequately supported by any means (e.g. size of home directories, problems regarding administration), then your usage will suffer greatly. The reverse situation, however, (i.e., a system supported better than your needs) is one of the key advantages to centralized computing.

History

The very first computers did not have separate terminals as such; their primitive input/output devices were built in. However, soon it was found to be extremely useful for multiple people to be able to use a computer at the same time, for reasons of cost – early computers were very expensive, both to produce and maintain, and occupied large amounts of floor space. The idea of centralized computing was born. Early text terminals used electro-mechanical teletypewriters, but these were replaced by cathode ray tube displays (as found in 20th century televisions and computers). The text terminal model dominated computing from the 1960s, until the rise to dominance of home computers and personal computers in the 1980s.

Contemporary status

As of 2007, centralized computing is now coming back into fashion – to a certain extent. Cloud computing has had an important role in the return of centralized computing. [1] Thin clients have been used for many years by businesses to reduce total cost of ownership, while web applications are becoming more popular because they can potentially be used on many types of computing device without any need for software installation. Already, however, there are signs that the pendulum is swinging back again, away from pure centralization, as thin client devices become more like diskless workstations due to increased computing power, and web applications start to do more processing on the client side, with technologies such as AJAX and rich clients.

In addition, mainframes are still being used for some mission-critical applications, such as payroll, or for processing day-to-day account transactions in banks. These mainframes will typically be accessed either using terminal emulators (real terminal devices are not used much any more) or via modern front-ends such as web applications – or (in the case of automated access) protocols such as web services protocols.

Diskless node model

Some organizations use a diskless node model partway between centralized computing and conventional desktop computing, in which some applications (such as web browsers) are run locally, while other applications (such as critical business systems) are run on the terminal server. One way to implement this is simply by running remote desktop software on a standard desktop computer.

Hosted computing model

A relatively new method of centralized computing, hosted computing, solves many of the problems associated with traditional distributed computing systems. By centralizing processing and storage on powerful server hardware located in a data center, rather than in a local office, it relieves organizations of the many responsibilities in owning and maintaining an information technology system. These services are typically delivered on a subscription basis by an application service provider (ASP). [2]

See also

Related Research Articles

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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.

<span class="mw-page-title-main">Thin client</span> Non-powerful computer optimized for remote server access

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.

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<span class="mw-page-title-main">Computer terminal</span> Computer input/output device for users

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.

In computer networking, a rich client is a computer that typically provides rich functionality independent of the central server. This kind of computer was originally known as just a "client" or "thick client," in contrast with "thin client", which describes a computer heavily dependent on a server's applications. A rich client may be described as having a rich user interaction.

The Network Computer was a diskless desktop computer device made by Oracle Corporation from about 1996 to 2000. The devices were designed and manufactured by an alliance, which included Sun Microsystems, IBM, and others. The devices were designed with minimum specifications, based on the Network Computer Reference Profile. The brand was also employed as a marketing term to try to popularize this design of computer within enterprise and among consumers.

<span class="mw-page-title-main">Client (computing)</span> Piece of software accessing a server service

In computing, a client is a piece of computer hardware or software that accesses a service made available by a server as part of the client–server model of computer networks. The server is often on another computer system, in which case the client accesses the service by way of a network.

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<span class="mw-page-title-main">Diskless node</span> Computer workstation operated without disk drives

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In computing, virtualization or virtualisation is the act of creating a virtual version of something at the same abstraction level, including virtual computer hardware platforms, storage devices, and computer network resources.

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MultiSeat Desktop Virtualization is a method by which a common desktop PC, with extra keyboards, mice, and video screens directly attached to it, can be used to install, load, and concurrently run multiple operating systems. These operating systems can be the same across all "seats" or they can be different. It is similar to server based computing only in the fact that one mainframe is supporting multiple users. On the other hand, it is different because the "terminals" are composed of nothing more than the regular keyboard, monitor and mouse, and these devices are plugged directly into the PC. USB hubs can be used for cable management of the keyboards and mice, and extra video cards may need to be installed.

<span class="mw-page-title-main">Wyse</span> American computing system manufacturer

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.

<span class="mw-page-title-main">Classes of computers</span>

Computers can be classified, or typed, in many ways. Some common classifications of computers are given below.

References

  1. Irion, Kristina (December 2012). "Government Cloud Computing and National Data Sovereignty". Policy & Internet. 4 (3–4): 40–71. doi:10.1002/poi3.10. ISSN   1944-2866.
  2. Core Desktop Solutions, Inc. Archived September 28, 2007, at the Wayback Machine . Retrieved on 5 September 2007.