Information Technology Reference
In-Depth Information
others? Can the Internet be re-designed to prevent denial-of-service,
spam, phishing, and other malicious behavior?
{ Illusionist. The Internet provides the illusion of a single worldwide
network, with the ability to deliver a packet from any machine on
the Internet to any other machine. However, network hardware is
in fact a large number of discrete network elements, with the ability
to transmit limited size packets over a limited distance, and with
some chance that the packet is garbled in the process. The Internet
transforms the network into something more useful for applications
like the web | a facility to reliably transmit data of arbitrary length,
anywhere in the world.
{ Glue. The Internet protocol suite was explicitly designed to act
as an interoperability layer, to allow network applications to evolve
independently of changes in network hardware, and vice versa. Does
the success of the Internet hold any lessons for operating system
design?
Many of these systems use the same techniques and design patterns as oper-
ating systems to address these challenges; studying operating systems is a great
way to understand how these others systems work. In a few cases, different
mechanisms are used to achieve the same goals, but even here, the boundary
can be fuzzy. For example, browsers often use compile-time checks to prevent
scripts from gaining control over the browser, while most operating systems
use hardware-based protection to limit application programs from taking over
the machine. More recently, however, some smartphone operating systems have
begun to use the same compile-time techniques as browsers, but for protect-
ing the smartphone operating system. In turn, some browsers have begun to
use operating system hardware-based protection to improve the isolation they
provide.
To avoid spreading our discussion too thinly, we focus this topic on how
operating systems work. Just as it is easier to learn a second computer pro-
gramming language after you are fluent in the first, it is better to see how these
operating systems principles are applied in one context before moving on to
how these concepts are applied in other settings. We hope and expect however,
that you will be able to apply the concepts in this topic more widely than just
operating system design.
Exercises
7. Society must also grapple with managing resources. What ways do we
use for allocating resources, isolating misuse, and fostering sharing in real
life?
