Unit – V
Elementary Internet
Application.
v INTRODUCTION TO INTERNET
In the
present age of information Technology, use of Internet is becoming quite
popular for accessing information on any topic of your interest. It also
provides tremendous opportunities to students, researchers and professionals
for getting information on matters related to academic and professional topics
and lot more. In the present world, most of the people who have computers
around themselves use Internet to access information from the World Wide Web,
exchange messages & documents and e-services.
v MEANING OF INTERNET
The
Internet is a global system of interconnected computer networks that use the
standard Internet protocol suite (TCP/ IP) to serve billions of users
worldwide. It is a network of networks that consists of millions of private,
public, academic, business, and government networks, of local to global scope,
that
are linked by a broad array of electronic, wireless and optical networking
technologies. The Internet carries a vast range of information resources and
services, such as the inter- linked hypertext documents of the World Wide Web
(WWW) and the infrastructure to support electronic mail.
v Uses of Internet
Internet
has been the most useful technology of the modern times which helps us not only
in our daily lives, but also our personal and professional lives developments.
The internet helps us achieve this in several different ways.
For
the students and educational purposes the internet is widely used to gather
information so as to do the research or add to the knowledge of various
subjects. Even the business professionals and the professionals like doctors,
access the internet to filter the necessary information for their use. The
internet is therefore the largest encyclopedia for everyone, in all age
categories. The internet has served to be more useful in maintaining contacts
with friends and relatives who live abroad permanently.
v Advantages of Internet:
E-mail: Email is now an essential
communication tools in business. With e-mail you can send and receive instant
electronic messages, which works like writing letters. Your messages are
delivered instantly to people anywhere in the world, unlike traditional mail
that takes a lot of time. Email is free, fast and very cheap when compared to
telephone, fax and postal services.
•24 hours a day - 7
days a week: Internet is available, 24x7 days for usage.
•Information:
Information is probably the biggest advantage internet is offering. There is a
huge amount of information available on the internet for just about every
subject, ranging from government law and services, trade fairs and conferences,
market information, new ideas and technical support. You can almost find any
type of data on almost any kind of subject that you are looking for by using
search engines like google, yahoo, msn, etc.
•Online Chat: You can access many
‘chat rooms’ on the web that can be used to meet new people, make new friends,
as well as to stay in touch with old friends. You can chat in MSN and yahoo
websites.
•Services: Many services are
provided on the internet like net banking, job searching, purchasing tickets,
hotel reservations, guidance services on array of topics engulfing every aspect
of life.
•Communities: Communities of all
types have sprung up on the internet. Its a great way to meet up with people of
similar interest and discuss common issues.
•E-commerce: Along with getting
information on the Internet, you can also shop online. There are many online
stores and sites that can be used to look for products as well as buy them
using your credit card. You do not need to leave your house and can do all your
shopping from the convenience of your home. It has got a real amazing and wide
range of products from household needs, electronics to entertainment.
•Entertainment:
Internet provides facility to access wide range of Audio/Video songs, plays
films. Many of which can be downloaded. One such popular website is YouTube.
•Software Downloads: You
can freely download innumerable, softwares like utilities, games, music,
videos, movies, etc from the Internet.
v Limitations of Internet
1. Theft of Personal information:
Electronic messages sent over the Internet can
be easily snooped and tracked, revealing who is talking to whom and what they
are talking about. If you use the Internet, your personal information such as
your name, address, credit card, bank details and other information can be
accessed by unauthorized persons. If you use a credit card or internet banking
for online shopping, then your details can also be ‘stolen’.
2. Negative effects on family
communication:
It is
generally observed that due to more time spent on Internet, there is a decrease
in communication and feeling of togetherness among the family members.
3. Internet addiction:
There
is some controversy over whether it is possible to actually be addicted to the
Internet or not. Some researchers, claim that it is simply people trying to
escape their problems in an online world.
4. Children
using the Internet has become a big concern. Most parents do not realize the
dangers involved when their children log onto the Internet. When children talk
to others online, they do not realize they could actually be talking to a
harmful person. Moreover, pornography is also a very serious issue concerning
the Internet, especially when it comes to young children. There are thousands
of pornographic sites on the Internet that can be easily found and can be a
detriment to letting children use the Internet.
5. Virus threat:
Today,
not only are humans getting viruses, but computers are also. Computers are
mainly getting these viruses from the Internet. Virus is is a program which disrupts
the normal functioning of your computer systems. Computers attached to internet
are more prone to virus attacks and they can end up into crashing your whole
hard disk.
6. Spamming:
It is
often viewed as the act of sending unsolicited email. This multiple or vast
emailing is often compared to mass junk mailings. It needlessly obstruct the
entire system. Most spam is commercial advertising, often for dubious products,
get-rich-quick schemes, or quasi-legal services. Spam costs the sender very
little to send — most of the costs are paid for by the recipient or the
carriers rather than by the sender
v SERVICES OF INTERNET -E-mail,
FTP, Telnet
Email,
discussion groups, long-distance computing, and file transfers are some of the
important services provided by the Internet. Email is the fastest means of
communication. With email one can also send software and certain forms of
compressed digital image as an attachment. News groups or discussion groups
facilitate Internet user to join for various kinds of debate, discussion and
news sharing. Long-distance computing was an original inspiration for
development of
ARPANET
and does still provide a very useful service on Internet. Programmers can
maintain accounts on distant, powerful computers and execute programs. File
transfer service allows Internet users to access remote machines and retrieve
programs, data or text.
(a) E-Mail
(Electronic Mail)
E-mail
or Electronic mail is a paperless method of sending messages, notes or letters
from one person to another or even many people at the same time via Internet.
E-mail is very fast compared to the normal post. E-mail messages usually take
only few seconds to arrive at their destination. One can send messages anytime
of the day or night, and, it will get delivered immediately. You need not to
wait for the post office to open and you don’t have to get worried about
holidays. It works 24 hours a day and seven days a week. What’s more, the copy
of the message you have sent will be available whenever you want to look at it
even in the middle of the night. You have the privilege of sending something
extra such as a file, graphics, images etc. along with your e-mail. The biggest
advantage of using e- mail is that it is cheap, especially when sending
messages to other states or countries and at the same time it can be delivered
to a number of people around the world.
It
allows you to compose note, get the address of the recipient and send it. Once
the mail is received and read, it can be forwarded or replied. One can even
store it for later use, or delete. In e-mail even the sender can request for
delivery receipt and read receipt from the recipient.
(i) Features of E-mail:
One-to-one or one-to-many communications
Instant communications
Physical presence of recipient is not required
Most inexpensive mail services, 24-hours a
day and seven days a week
encourages informal communications
(ii) Components of an E-mail Address
As in
the case of normal mail system, e-mail is also based upon the concept of a
recipient address.
The email address
Provides
all of the information required to get a message to the recipient from any
where in the world. Consider the e-mail ID.
Shivvkumar.p@gmail.com
In the
above example shivv is the username of the person who will be sending/receiving
the email. gmail is the mail server where the username shivv has been
registered and com is the type of organization on the internet which is hosting
the mail server.
(b) FTP (File
Transfer Protocol)
File
Transfer Protocol, is an Internet utility software used to uploaded and
download files. It gives access to directories or folders on remote computers
and allows software, data and text files to be transferred between different
kinds of computers. FTP works on the basis of same principle as that of Client/
Server. FTP “Client” is a program running on your computer that enables you to
communicate with remote computers. The FTP client takes FTP command and sends
these as requests for information from the remote computer known as FTP
servers. To access remote FTP server it is required, but not necessary to have
an account in the FTP server. When the FTP client gets connected, FTP server
asks for the identification in terms of User Login name and password of the FTP
client . If one does not have an account in the remote FTP server, still he can
connect to the server using anonymous login.
Using
anonymous login anyone can login in to a FTP server and can access public
archives; anywhere in the world, without having an account. One can easily
Login to the FTP site with the username anonymous and e-mail address as
password.
v World Wide Web (WWW)
WWW
stands for World Wide Web. A technical definition of the World Wide Web is :
all the resources and users on the Internet that are using the Hypertext
Transfer Protocol (HTTP).
A
broader definition comes from the organization that Web inventor Tim
Berners-Lee helped found, the World Wide Web Consortium (W3C).
The
World Wide Web is the universe of network-accessible information, an embodiment
of human knowledge.
In
simple terms, The World Wide Web is a way of exchanging information between
computers on the Internet, tying them together into a vast collection of
interactive multimedia resources.
Internet
and Web is not the same thing: Web uses internet to pass over the information.
The World Wide Web allows computer users to locate and view multimedia-based
documents (i.e., documents with text, graphics, animations, audios or videos)
on almost any subject.
Even though the Internet was developed more than three decades ago, the
introduction of the World Wide Web is a relatively recent event. In 1990, Tim
Berners-Lee of CERN (the European Laboratory for Particle Physics) developed
the World Wide Web and several communication protocols that form the backbone
of the Web.
The Internet and the World Wide Web surely will be listed among the most
important and profound creations of humankind.
In the past, most computer applications executed on “stand-alone” computers
(i.e., computers that were not connected to one another).
The W3C is also a standardization organization.
Web technologies standardized by the W3C are called Recommendations. W3C
Recommendations include the Extensible Hyper-Text Markup Language (XHTML),
Cascading Style Sheets (CSS), Hypertext Markup Language (HTML; now considered a
“legacy” technology) and the Extensible Markup Language (XML).
The W3C homepage (www.w3.org) provides extensive resources on Internet and Web
technologies
WWW
Operation
WWW
works on client- server approach. Following steps explains how the web works:
1. User
enters the URL (say, http://www.tutorialspoint.com) of the web page in the
address bar of web browser.
2. Then
browser requests the Domain Name Server for the IP address corresponding to
www.tutorialspoint.com.
3. After
receiving IP address, browser sends the request for web page to the web server
using HTTP protocol which specifies the way the browser and web server
communicates.
4. Then
web server receives request using HTTP protocol and checks its search for the
requested web page. If found it returns it back to the web browser and close
the HTTP connection.
5. Now
the web browser receives the web page, It interprets it and display the
contents of web page in web browser’s window.
v Search Engine
Search
Engine refers to a huge database of internet resources such as web pages,
newsgroups, programs, images etc. It helps to locate information on World Wide
Web.
User
can search for any information by passing query in form of keywords or phrase.
It then searches for relevant information in its database and return to the
user.
Search Engine Components
Generally
there are three basic components of a search engine as listed below:
1. Web
Crawler
2. Database
3. Search
Interfaces
Web crawler
It
is also known as spider or bots. It is a software component that traverses the
web to gather information.
Database
All
the information on the web is stored in database. It consists of huge web
resources.
Search Interfaces
This
component is an interface between user and the database. It helps the user to
search through the database.
v Search Engine Working
Web
crawler, database and the search interface are the major component of a search
engine that actually makes search engine to work. Search engines make use of
Boolean expression AND, OR, NOT to restrict and widen the results of a search.
Following are the steps that are performed by the search engine:
The
search engine looks for the keyword in the index for predefined database
instead of going directly to the web to search for the keyword.
It
then uses software to search for the information in the database. This software
component is known as web crawler.
Once
web crawler finds the pages, the search engine then shows the relevant web
pages as a result. These retrieved web pages generally include title of page,
size of text portion, first several sentences etc.
These
search criteria may vary from one search engine to the other. The retrieved
information is ranked according to various factors such as frequency of
keywords, relevancy of information, links etc.
User
can click on any of the search results to open it.
Examples
Following
are the several search engines available today:
|
Search Engine |
Description |
|
Google |
It was originally
called BackRub. It is the most popular search engine globally. |
|
Bing |
It was launched in
2009 by Microsoft. It is the latest web-based search engine that also
delivers Yahoo’s results. |
|
Ask |
It was launched in
1996 and was originally known as Ask Jeeves. It includes support for match,
dictionary, and conversation question. |
|
AltaVista |
It was launched by
Digital Equipment Corporation in 1995. Since 2003, it is powered by Yahoo
technology. |
|
AOL.Search |
It is powered by
Google. |
|
LYCOS |
It is top 5 internet
portal and 13th largest online property according to Media Matrix. |
|
Alexa |
It is subsidiary of
Amazon and used for providing website traffic information. |
v Web browser:
web
Browser is an application software that allows us to view and explore
information on the web. User can request for any web page by just entering a
URL into address bar.
Web
browser can show text, audio, video, animation and more. It is the
responsibility of a web browser to interpret text and commands contained in the
web page.
Earlier
the web browsers were text-based while now a days graphical-based or
voice-based web browsers are also available.
Alternatively
referred to as a web browser or Internet browser, a browser is a software
program to present and explore content on the World Wide Web. These pieces of
content, including pictures, videos, and web pages, are connected using
hyperlinks and classified with URIs (Uniform Resource Identifiers). This page
is an example of a web page that can be viewed using a browser.
There
have been many different web browsers that have come and gone over the years.
The first, named WorldWideWeb (later changed to Nexus), was invented by Tim
Berners-Lee in 1990. However, the first graphical browser and widely used
browser that help bring popularity to the Internet was NCSA Mosaic. Examples of
web browsers
