Java Reference
In-Depth Information
processes information. The second piece is the Internet address of the machine on
which the document is stored. The third piece of information is the file name or
resource of interest. If no file name is given, as is the case with the Google URL,
the Web server usually provides a default page (such as index.html).
Let's look at another example URL:
In this URL, the protocol is http, which stands for
HyperText Transfer Protocol
.
The machine referenced is
www
(a typical reference to a Web server), found at
domain
whitehouse.gov
. Finally,
photos-and-video/photogallery/photo-day
represents a file (or a reference that generates a file) to be transferred to the browser
for viewing. Many other forms for URLs exist, but this form is the most common.
SELF-REVIEW QUESTIONS
(see answers in Appendix N)
SR 1.14
What is a file server?
SR 1.15
What is the total number of communication lines needed for a fully
connected point-to-point network of five computers? Six computers?
SR 1.16
Describe a benefit of having computers on a network share a communica-
tion line. Describe a cost/drawback of sharing a communication line.
SR 1.17
What is the etymology of the word Internet?
SR 1.18
The TCP/IP set of protocols describes communication rules for soft-
ware that uses the Internet. What does TCP stand for? What does IP
stand for?
SR 1.19
Explain the parts of the following URLs:
a. duke.csc.villanova.edu/jss/examples.html
b. java.sun.com/products/index.html
Let's now turn our attention to the software that makes a computer system use-
ful. A program is written in a particular
programming language
that uses specific
words and symbols to express the problem solution. A programming language
defines a set of rules that determines exactly how a programmer can combine the
words and symbols of the language into
programming statements,
which are the
instructions that are carried out when the program is executed.
Since the inception of computers, many programming languages have been
created. We use the Java language in this topic to demonstrate various program-
ming concepts and techniques. Although our main goal is to learn these underlying
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