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Fig. 4: A terminal is made up of a monitor, a keyboard, and a connection to the server. Notice that the screen contains only text.
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the first, the terminal |
The earliest forms of distributed computing made use of a crude form of
networking in which the client computers wholly depended on the server's services —
including the display output and applications (Burghart). In fact, the client sends
every keystroke to the server for processing, and then the server tells the client what to display on
its screen. Although the server seems to handle all the tasks, these clients — known
as terminals — handle part of the presentation layer of an application by taking care of
keyboard input and display output. Terminals are widely employed in libraries as digital card
catalogs and in data warehouses.
Advantages to the terminal interface system are the low maintenance and cost
of the terminals. Terminals are not difficult to program, because the programmer does not need to
incorporate communication routines into his program (Burghart). The terminal automatically
displays whatever the server sends, whereas regular client computers need software to interpret
the server's messages and then show it onscreen. However, the text-only interface limits the
functionality of terminals, and may be difficult for users who prefer the mouse-driven graphical
user interfaces offered by Windows and Macintosh.
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Fig. 5: The anatomy of a terminal system
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continued...
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application server
