Databases Reference
In-Depth Information
INTRODUCTION
Over the years, two arrangements for locating data other than ''in the computer
itself'' have been developed. Both arrangements involve computers connected to
one another on networks. One, known as ''
client/server database
,'' is for personal
computers connected together on a local area network. The other, known as
''
distributed database
,'' is for larger, geographically dispersed computers located
on a wide-area network. The development of these networked data schemes has
been driven by a variety of technical and managerial advantages, although, as is so
often the case, there are some disadvantages to be considered as well.
CLIENT/SERVER DATABASES
A
local-area network (LAN)
is an arrangement of personal computers connected
together by communications lines, Figure 12.1. It is ''local'' in the sense that the
PCs must be located fairly close to each other, say within a building or within several
nearby buildings. Additional components of the LAN that can be utilized or shared
by the PCs can be other, often more powerful ''
server
'' computers and peripheral
devices such as printers. The PCs on a LAN can certainly operate independently
but they can also communicate with one another. If, as is often the case, a LAN is
set up to support a department in a company, the members of the department can
communicate with each other, send data to each other, and share such devices as
high-speed printers. Finally, a
gateway computer
on the LAN can link the LAN
and its PCs to other LANs, to one or more mainframe computers, or to the Internet.
PC
PC
PC
Server
PC
Printer
PC
PC
F I G U R E 12.1
Local area network (LAN)
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