Access Controls An access control system

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[edit] History

Batch processing has been associated with mainframe computers since the earliest days of electronic computing in the 1950s. Because such computers were enormously costly, batch processing was the only economically-viable option of their use. In those days, interactive sessions with either text-based computer terminal interfaces or graphical user interfaces were not widespread. Initially, computers were not even capable of having multiple programs loaded into the main memory.

Batch processing has grown beyond its mainframe origins, and is now frequently used in UNIX environments and Microsoft Windows too. UNIX systems use shells and other scripting languages. DOS systems use batch files powered by COMMAND.COM, Microsoft Windows has cmd.exe, Windows Script Host and advanced Windows PowerShell.

[edit] Modern Systems

Despite their long history, batch applications are still critical in most organizations. While online systems are now used when mannual intervention is not desired, they are not well suited to the high-volume, repetitive tasks. Therefore, even new systems usually contain a batch application for cases such as updating information at the end of the day, generating reports, and printing documents.

Modern batch applications make use of modern batch frameworks such as Spring Batch, which is written for Java, to provide the fault tolerance and scalability required for high-volume processing. In order to ensure high-speed processing, batch applications are often integrated with grid computing solutions to partition a batch job over a large number of processors.

[edit] Common batch processing usage

[edit] Printing

A popular computerized batch processing procedure is printing. This normally involves the operator selecting the documents they need printed and indicating to the batch printing software when, where they should be output and priority of the print job. Then the job is sent to the print queue from where printing daemon sends them to the printer.

[edit] Databases

Batch processing is also used for efficient bulk database updates and automated transaction processing, as contrasted to interactive online transaction processing (OLTP) applications.

[edit] Images

Batch processing is often used to perform various operations with digital images. There exist computer programs like Batch Image Processor that let one resize, convert, watermark, or otherwise edit image files.

[edit] Converting

Batch processing is also used for converting a number of computer files from one format to another. This is to make files portable and versatile especially for proprietary and legacy files where viewers are not easy to come by.

Job scheduling

UNIX utilizes cron and at facilities to allow for scheduling of complex job scripts. Windows has a job scheduler. Most high-performance computing clusters use batch processing to maximize cluster usage.
Batch Total

Checks for missing records. Numerical fields may be added together for all records in a batch. The batch total is entered and the computer checks that the total is correct, e.g., add the 'Total Cost' field of a number of transactions together.

Bit
In computing and telecommunications a bit is a basic unit of information storage and communication (a contraction of "binary digit"). It is the maximum amount of information that can be stored by a device or other physical system that can normally exist in only two distinct states. These states are often interpreted (especially in the storage of numerical data) as the binary digits 0 and 1. They may be interpreted also as logical values, either "true" or "false"; or two settings of a flag or switch, either "on" or "off".

In information theory, "one bit" is typically defined as the uncertainty of a binary random variable that is 0 or 1 with equal probability,^[1] or the information that is gained when the value of such a variable becomes known.^[2]

Byte

There are several units of information which are defined as multiples of bits, such as byte (8 bits), kilobit (either 1000 or 2¹⁰ = 1024 bits), megabyte (either 8,000,000 or 8×2²⁰ = 8,388,608 bits), etc.

Centralized Processing

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.

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).

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.

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