2 1. DISTRIBUTED COMPUTING
is book gently introduces the general reader to some of the basic principles and some
of the fascinating results of computer science which involve interactions between computing
devices (or processors on the same or different devices), so that the reader can get a feel of
the nature of this exciting and interesting field called distributed computing. ese fundamental
principles and results, underlying the design of algorithms for distributed systems, are presented
by comparing issues that arise when dealing with groups of computing devices to those that arise
when a group of people has to share their resources and work as a team to solve various problems.
e book is self-contained; no reliance is made on previous knowledge in computer science. In
particular, all the figures in the book which include code segments can be skipped without loss
of continuity.
1.2 THE INTERNET
e Internet is a vast collection of computer networks which are connected into a single huge
network. It is used for the transport of data and messages across distances which can be anywhere
from the same room to anywhere in the world. It provides an infrastructure for the use of E-mail,
banking, commerce, education, entertainment, telecommunications, manufacturing, and social
networks and enables the sharing of remote resources such as databases, files, discs, printers,
and computational resources. It also enables several computers to solve problems together much
faster than any computer can do alone.
Historically, the Internet was designed as a research network without the expectation that
it would have a significant role in our daily lives. e scale and heterogeneity of the Internet
have far surpassed all expectations. As the Internet continues to grow, more and more business-
critical functions rely on its availability. e vast majority of communications traffic, including
telephone, television, radio, business data, and government data, rely on an Internet infrastruc-
ture that is available and secure.
Many applications of large-scale computer networks, such as the Internet, require a high
level of reliability and security, for example, an air traffic control system, spacecraft navigation
systems, or an integrated corporate management system. As the system size increases, so does the
need to design fault-tolerant applications, for the probability that the entire system functions
correctly at any given time rapidly approaches zero. Such applications enable the system as a
whole to continue to function despite the failure of a limited number of components.
Today’s economy involves manufacturing, distributing, and retailing of goods. However,
it also has to do with creating and disseminating information, for example, publishing books,
filmmaking, etc. Future economy is likely to be dominated by information. Information is a rep-
resentation of knowledge, and can be represented in two ways: analog—a book that you can hold
in your hand; or digital—a book that is stored as a file in your computer. e digital revolution
is about converting analog information to digital information and use computer networks such
as the Internet to move the digital information around. Such networks are required to be able to
move the information in large quantities, everywhere, cheaply, securely, and as fast as possible.
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