CLIENT/WEB SERVERS STRUCTURE OF THE WEB
CLIENT/SERVER
STRUCTURE OF THE WEB
Web is a collection of files that reside on
computers,
called Web servers, that are located all
over the world and are connected to each other through the Internet.
When you use your Internet connection to
become part of the Web, your computer becomes a Web client in a worldwide
client/server network.
A Web browser is the software that you
run on your computer to make it work as a web client.
HPERTEXT
MARKUP LANGUAGE (HTML)
The public files on the web servers are
ordinary text files, much like the files used by word-processing software.
To allow Web browser software to read
them, the text must be formatted
according to a generally accepted standard.
The standard used on the web is Hypertext
markup language (HTML).
HTML uses codes, or tags, to tell the Web
browser software
how to display the text contained in the
document.
For example, a Web browser reading the
following line of
text:
<B> A Review of the Book<I>Wind
Instruments of the 18th Century</I></B>
recognizes the <B> and </B>
tags as instructions to display the entire line of text in bold and the
<I> and </I> tags as instructions to display the text enclosed by
those tags in italics.
ADDRESS
ON THE WEB: IP ADDRESSING
Each computer on the internet does have a
unique identification number, called an IP (Internet Protocol) address.
The IP addressing system currently in use
on the Internet uses a four-part number.
Each part of the address is a number
ranging from 0 to 255, and each part is
separated from the previous part by period,
For example, 106.29.242.17
IP
ADDRESSING
The combination of the four IP address
parts provides 4.2 billion possible
addresses (256 x 256 x 256 x 256). (IPV4)
This number seemed adequate until 1998.
Members of various Internet task forces
have worked to develop an alternate
addressing system that will accommodate the
projected growth. (IPV6
Most web browsers do not use the IP
address t locate Web
sites and individual pages.
They use domain name addressing.
A domain name is a unique name associated
with a specific IP address by a program that runs on an Internet host computer.
This program, which coordinates the IP
addresses and domain names for all computers attached to it, is called DNS
(Domain Name System ) software.
The host computer that runs this software
is called a
domain name server.
DOMAIN NAME ADDRESSING
Domain names can include any number of
parts separated by periods, however most domain names currently in use have
only three or four parts.
Domain names follow hierarchical model
that you can follow from top to bottom if you read the name from the right to
the left.
For example, the domain name
gsb.uchicago.edu is the computer connected to the Internet at the Graduate
School of Business (gsb), which is an academic unit of the University of
Chicago (uchicago), which is an educational institution (edu).
No other computer on the Internet has the
same domain name.
Endings of web pages tells us a bit about the page. Some common endings
to web addresses are:
com (commercial)
edu (educational institution)
gov (government)
net (network)
org (organization)
You might also see addresses that add a country code as the last part of
the address such as:
TZ(Tanzania)
uk (United Kingdom)
fr (France)
us (United States of America)
au (Australia)
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