This article throws light upon the top three classes of Distributed Data Processing. The Classes are: 1. Data Entry Systems 2. Stand-Alone Systems 3. Computer Networks
Data entry station has both softcopy (temporary, visual display) and hardcopy (permanent. printed) output capability.
The control units control communications between the host, central-site computer and the data entry station.
The dump terminals transmit all data directly to the central site computer (server). This type of data called “dirty” because errors are also transmitted along with good data.
In order to achieve good and accurate data, first of all the errors available within the data is identified at the central site, and processing could be delayed until the error is not removed and “clean” data are obtained from remote users. This type of delay, by the need to process the data all over again can be expensive.
Intelligent terminals have a limited local-processing capability i.e., the input data take place locally and that the data can be made error-free before it is transmitted to the central-site computer (server). The terminal has some local processing power and storage capacity in addition to input and output capabilities.
Programmable terminals are distributed data processing systems with extensive local data processing powers. Large working files can be maintained locally. Only the data that are needed at the central-site have to be transmitted and transmission can take place when it is convenient to schedule it.
DDP implies communication between a host computer and remote station, but a communication link is not essential. The responsibility for performing entire functions may be distributed. Independent or stand-alone computer system may be able to meet the need of separate departments or branches of large corporations.
Stand-alone DDP can improve the effectiveness of the local operations, especially if files are maintained and managed locally. Stand-alone system may be general-purpose computers or specialized programmable data entry systems with a secondary emphasis upon communications. The use of microcomputers as standalone systems has tremendous potential.
The most complex form of distributing the data processing function is computer network. A network attaches multiple computers together for the purpose communicating data and sharing resources. The major complication of the computer network is the software required to allow the computers to “talk” to the other.
On the basis of the geographical area covered by the network we can classify them as Local area network (LAN) and wider area network (WAN).
The general Topology of computer networks is the Star and the Ring. If the network is entirely within a business, it is called a local area network (LAN). Telecommunication network covering a large geographical area is called remote network, long distance network, or Wide Area Network (WAN).
(i) Local Area Network:
It is an intra-company, privately owned, user-administrated network. It covers only few miles. The configuration of LAN can be Star, a Ring or a simple device attach along a length of cable. The typical LAN connects computers located within half a mile of each other.
The computers attached may be of different types of configuration and perform different functions such as word, processing, graphics and electronic mail as per the users’ requirement.
The main purpose of the local area network is to link workstations within a facility so that they may share peripherals and to permit workstation to communicate with each other. The LAN is connected to an inter-city network or value added network to have access of outside sources of data.
(ii) Wider Area Network:
Network covering a large city or metropolitan area (Metropolitan Area Network) can also be included in this category. Such networks are becoming necessary of carrying out the day to day activities of many business organizations and governmental organizations and their end users. Manufacturing firms, bank, retailers, distributors and transportation companies etc. uses them. Internet and E-business are the example.