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Evolution of Computing Architectures

Let us discuss about the evolution of client-server architecture for various computing models in this section. The three system architectures namely the centralized, file server and client server are discussed at length here. To begin with let us get acquainted with the centralized system.

Centralized System Architecture

Companies that needed real computing power turned to the mainframe computer, which is centralized system architecture. The salient most features of the centralized system is that the only movement of marshalling are the keystrokes between the client and the host machine. Marshalling is the process of packaging interface elements and sending them across process boundaries. Thus in a centralized system, keystrokes are marshaled from the terminal (client) to the host. The centralized system architecture is illustrated in the figure shown below. This is very different from the currently available client-server architecture. The pros and cons of using this type of architecture are listed below.

Advantages of Centralized System Architecture

  • Excellent Security

  • Centralized administration as both application logic and data reside on the same machine

Disadvantages of Centralized System Architecture

  • Mainframe computers are very expensive to buy, lease, maintain and use

  • The limitation is that both the application and the database live within the same machine process thereby offering no way to partition the application logic beyond the physical limitations of the mainframe.

In 1980s, the personal computers made an entry into the business world along with which, came the resources like printers, modems and hard-disk storage. The introduction of the local area network (LAN) and the use of file server architectures soon followed the introduction of personal computer.


  

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