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Following are three models for network computing., i) Centralised computing, , ii) . Distributed computing, , iti) Collaborative or co-operative computing, , These three models are the basis for various types of computer networks., , Centralised Computing, , Centralised computing model involves the following :, i) All processing takes place in the central main frame computer., , ii) Terminals are connected to the central computer and function only as input / output devices., , Fig. 5.1 shows centralised computing., , 100% of computing No computing, , , , , , Mainframe, , , , , , No computing, , , , No computing, , , , Dumbterminal, , , , Printer, Fig. 5.1 : Centralised Computing, , This computing was used in early days in large organisations. One of the drawbacks was that, , mainframe used to require Jarge size room.

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Distributed Computing, Distributed computing involves the following :, i) Multiple computers capable of processing independently., , ii) Task completion by the local computer or other computers on the network., , With development of personal computers (PCs) the distributed computing emerged. Fig. 5.2, , shows distributed computing., 70% of the processing, , , , , , , , , , , , , , , , , , , , , , , , , , a, 30% of the processing i, Information flows, —, , , , , , , , , , , , Fig. 5.2 : Distributed Computing, , Distributed processing was a major step forward. It provided smaller business with their own, computational capabilities., , Collaborative Computing, , Collaborative computing enables computers in a distributed c, processing power in addition to data. resources and services., , omputing environment to share, , Collaborative computing involves the following :, i) Multiple computers co-operating to perform a task., ii) Software designed to take advantage of collaborative environment., , A person browsing on Internet is an example of collaborative computing. Microsoft server, based products such as Exchange server or SQL server are examples of collaborative computing.