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U. Glaeser

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Client–Server Computing<br />

Client–server computing was developed to address cost-effective computing and communication capability.<br />

Clients use low cost terminals to make service requests from servers. In this manner, server costs<br />

and services are shared between all users and minimized. Figure 5.1 depicts client–server information<br />

processing model.<br />

In late 1970s and early 1980s, business computing and communication infrastructure needs were met<br />

via one or more centralized mainframes connected to user terminals via networks. Figure 5.2 illustrates<br />

this model. In most cases, client low-computing-need program processes are executed on the terminals<br />

while mainframe servers execute the more expensive request-handling programs. The mainframe servers<br />

provided a centralized resource for most computing needs as well as other tasks such as data storage,<br />

external network interfaces, and task management. In late 1980s and early 1990s, the enterprise IT evolved<br />

due to advent of personal computers (PCs) fueled by the availability of inexpensive powerful microprocessors.<br />

In the new IT infrastructure, many of the tasks previously provided by the servers were processed<br />

locally by the PCs.<br />

In late 1990s and now, explosive growth of Internet as the common communication medium has<br />

resulted in yet another change to the IT infrastructure. Due to advent of World Wide Web (WWW) and<br />

other related technologies, many e-commerce businesses electronically automate customer request processing.<br />

Some of the characteristics of the new environment are:<br />

• Simple and robust user interfaces (typically Web-based services) for customer entry request entry<br />

and response display<br />

• High-speed networks for data transmission<br />

• Powerful centralized systems to handle data storage, transaction processing, and inventory<br />

management<br />

FIGURE 5.1<br />

FIGURE 5.2<br />

© 2002 by CRC Press LLC<br />

Client and server model.<br />

Network<br />

Interconnect<br />

Client<br />

Computing and communication infrastructure.<br />

Server<br />

IDC<br />

Network Interconnect<br />

Client Server<br />

Client<br />

IDC<br />

Network<br />

Network<br />

Hub<br />

Hub<br />

Client Client

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