Transcript INTERNET TECHNOLOGIES

By
Dr. Veer Sain Dixit
Deptt. Of Computer Science
Arsd College , University of Delhi
Introduction
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Internet is an interconnection between the computers cited at the remote
locations in the world wide web (www) . The Internet is a huge network of
computers, which links many different types of computers all over the world.
Internet is a network of networks or collection of LANs (Local Area
Networks) which share a common set of protocols for communications
between two computers between the LANs.
•
The Internet has it’s root in the ARPANET system of the Advanced research
Project Agency of the US Department of Defence . ARPANET was the first
WAN (Wide Area Network) and had only four sites in 1969.
In the 1980s the National Science Foundation of USA officially created the
Internet.
Intranet is the Interconnection between the computers cited at the remote
locations pertaining to only one organization.
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Services Provided by the Internet
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E-mail : E-mail provides a mechanism for groups of people who have
common interests to establish and maintain contact.
FTP : FTP is an abbreviation for File Transfer Protocol. FTP is used to send
a copy of a file from a one computer to another. The files can be sent across
using FTP include spreadsheets , digitized pictures , sound files , programs
, word – processed files etc.
TELNET : This service allows you to log-on to a remote machine , on which
you have your account.
Usenet Newsgroups : There are many ways to meet people and share
information – using Internet. One such way is Usenet newsgroups. These
are special groups set up by people who want to share common interests
ranging from current topics to cultural heritage. There are currently
thousand of newsgroups.
Network can be classified into two
categories:
Point to Point channel network : The two
computers that are not connected by a cable
can communicate only via other intermediate
components. The information is stored in its
entirety and later forwarded when the line is
free. This is also called as packet switching.
• Broadcast channel network : A single channel will be
shared by all the machines on the network. There is an
address field within the message that specifies the
destination. This network is called multidrop network.
Three most commonly used
networks are
• LAN:
Uses
broadcast
channel
for
communication. Spans an area of not more than
a few kilometers. Atotal data rate of several
mbps. Owned by a single organization.
• WAN : Uses point to point links. Spans the entire
country. Has a data rate below 1 Mbps. Owned
by multiple organizations.
• MAN : This lies between LAN and WAN. Uses
LAN technology. Spans the entire city.
TOPOLOGIES
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Star : A central hub is connected to various computers. The hub is in
complete control of all computers and is responsible for routing traffic. It is
easy to identify the fault points by isolating the lines.
Hierarchical : Also known as vertical network or tree network. The computer
at the highest level of hierarchy is in control of the network. Any number of
subordinate computers can be added to the network.
Bus : Asingle station broadcasts to multiple stations. Only one
communication channel exists for all the devices on the network. If the main
communication channel fails , the entire network crashes. It is difficult to
isolate faults to one particular component that is connected to the bus. This
is used in LAN.
Ring : It is widely used for network configuration. Data flow is in one
direction only. One computer receives the signal and relays it to the next
computer on the ring. It is a major drawback because if a channel between
two nodes fails , the network is lost. We can build bypass switches to avoid
such failures.
Global Reach / Penetration of
Interactive Services:
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Total internet users in Europe and in the World: [Internet World Stats, January 2006]
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Europe:
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World: 1,018,057,389
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Total internet users by country and share of world users:
202,888,307
(21.6% share)
[Nielsen// NetRatings, June, 2005]
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290,121,957
China:
103,000,000
Japan:
78,050,000
Germany: 47,127,725
India:
39,200,000
UK:
35,807,929
(11%)
(8.3%)
(5.0%)
(4.2)
(3.8%)
[CNNIC, June, 2005]
[C+I+A, March, 2005]
[Nielsen// NetRatings , June, 2005]
[ C.I.Almanac , March, 2005]
[Nielsen// NetRatings, June, 2005]
There will be 1.07 billion internet users globally by 2005, 1.21 billion by 2006 and 1.35 billion by
2007. [ eTForecasts , Sept 2004]
Internet Usage and Population
growth Statistics in India:
Internet Usage and Population
growth Statistics in India:
India Internet and
Telecommunications Reports
• July 7, 2004 - Women lead rural India's internet rush. The internet is
beginning to have a revolutionary effect on the 700 million people
who live in villages in India - and the charge is being led by women.
A project set up by one of India's leading technology institutes has
put women in charge of forging the way across the digital divide as
the proprietors of a fast-growing number of internet cafes or kiosks
around the sub-continent. In total 80% of these new kiosks are run
by women, many of whom have had very little or no acquaintance
with technology before. ( BBC News).
India - Internet and E-Services
Market Report
• Despite the considerable popular interest in Internet in India, the ISP
market has been in disarray. According to the telecom regulator,
there were around 180 operational ISPs in the country, after a period
of market rationalization . Despite the large number of providers,
10% of the ISPs have 90% of the subscribers. The state-owned –
BSNL and MTNL – have grown rapidly to hold first and second place
in terms of subscribers. The growing popularity of cyber cafes has
been playing a big role in fuelling Internet development in India. This
report looks at the ISPs and other aspects of India’s Internet market.
There is also some information on Internet content and e-services.
India - Broadband and Data
Services Report
• February 16, 2006 - Broadband usage in India is
growing 20% per month, according to the
Internet Service Providers Association of India
(ISPAI). Thanks to the progress in the past two
years and especially, the Broadband Policy
announced a year ago, the term “broadband”
has entered mass lexicon and most Internet
users are aware of faster speeds. ( ISPAI
Article).
February 17, 2006 - An overview of
Internet usage in India.
• The state-owned Videsh Sanchar Nigam Limited (VSNL)
launched Internet Services in India in August 1995. For
the first four years , VSNL was the sole provider of
Internet Services in the Country. In November 1998, the
Government ended VSNL’s monopoly and allowed
provisioning of Internet Services by Private Operators.
The Terms and Conditions of the ISP’s License were
unusually liberal with no License Fee and allowed
unlimited number of players. ISPs could set their own
tariffs and even their own International Gateways.
Internet
Addresses
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The Internet is a interconnection between the computers cited at the remote
site that are able to talk to each other in spite of the fact that they may be
separated by large distances, may be very different computers built by
different manufacturers, and may be running many different kinds of
operating systems. This is similar to people in (say) India,Israel, Brazil,
Japan, spain,the United States, and pakistan, each normally speaking a
different language, being able to converse almost instantaneously with each
other on very broad ranges of topics!
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The computers of the Internet exchange packets of information using
addresses . These addresses are called Internet Protocol (IP) addresses.
TCP/IP Protocols
• The communications between the computers
are possible because of a set of protocols, which
is a set of rules about exactly how information
will be transferred between the computers of the
Internet. The two most important protocols that
allow networks to cooperate with one another
and exchange information are called TCP
(Transmission Control Protocol) and IP (Internet
Protocol). Collectively, these two protocols are
known as TCP/IP.
Packets of Information
• The information is transferred in terms of electronic
packets. Packets must have an address. TCP/IP
communication depends on addresses being included in
each packet. these addresses are commonly termed "IP
addresses". As these packets of information move
through the network, electronic devices called routers
use these IP addresses to decide whether to keep a
packet in a local network or to forward it to a different
network. This is a complex task, because there are many
networks that either comprise the Internet, or that are
attached to it through some gateway.
Addresses
• Each computer has a number that tells you many things about
it. On the internet each machine is assigned a host number
which is a 32-bit binary number: four numbers separated by
dots.
• Addresses for Internet information packets have four fields that
contain numbers and are separated by periods. For example,
100.35.04.15 is an IP address. However, people generally can
remember names better than numbers, so it is convenient to
associate a name with such an IP address. In this case, the
corresponding name is
www.arsdcollege.net.
The Naming System
• Let us consider as a typical example the internet address
www.arsdcollege.net , which is actually the name of the IP
address 50.26.24.07. How did the people who run the
Internet come up with that name, and how did we know
that www.arsdcollege.net is really a nickname for
50.26.24.07?
• The symbolic name of a site is determined by a naming
standard known as the Domain Name System or DNS.
• DNS is a textual addressing method.
• Each field in a symbolic address corresponds to a single
domain. The first field is a host name, which identifies a
single computer. The last field is a top level domain. In
between are things like department names, organization
names, and so on in order of increasing generality.
URL Details
• The URL(Uniform Resource Locator) provides a
reasonably intelligent form to uniquely identify or
address information on the internet.
• URL addresses have 2 parts: (1) a portion
specifying the method of file access, and (2) a
portion specifying the Internet location of the file
to be accessed.
The example of the address
http://www.arsdcollege.net/index.html
Search Engines
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A search engine is a program that can search the Web on a specific topic
for you. By typing in a word or phrase (known as a keyword), the search
engine will produce pages of links on that topic. Supposedly, the more
relevant links are at the top of the list, but that is not always true. To
understand more specifically how search engines, operate visit How Search
Engines Work.
Example: the Searchalot Search Engine
An example of a search engine is the popular Searchalot Search Engine.
The homepage of this web site includes a small window, which you can type
a word or set of words on a topic you are interested in.
Suppose you wanted to locate information about Cricket on the Web. You
could go to the searchalot site and enter your query in the entry field:
• You then press on " Search" (other search
engines will have slightly different forms). The
search engine will respond by providing you with
a list of all the documents in its database that
contain the word “cricket". Your browser will
display a page with your keyword(s) and a list of
documents in which the engine found the
word(s). For a searchalot search on “cricket", the
results will look like:
Sharpening the Search
• If the keyword you specify for the search is a rather
common term, you may be presented with an enormous
number of Web documents that contain that term. In this
case many of the hits may contain the term but in only
one or two instances. Rather than wasting a lot of your
time looking through the long list and visiting links that
may turn out to have little or nothing to do with the topic
you are really interested in, you can let the search
engine do the sifting by repeating your search with
additional and more specific keywords.
General tips to help your search:
• Be as specific as possible. For example, maybe you are really only
interested in cricket information on the delhi clubs, then you should
use the term “delhi clubs" instead of the general term of “cricket."
If you're truly interested in the “Delhi clubs" wrap the term in quotes.
This means you want both words together. Otherwise you will pull
travel web sites about the city of Delhi .On most search engines
adding a plus sign (+) next to any term means to be sure and
include the term in the results. If you want very specific information
about the ‘Delhi clubs’ 2007 season , put a plus sign (+) next to both
terms. For example +“Delhi clubs " and +2007 means that you want
only links that have both information about the clubsand their
activities during the year 2007.
Other Search Engines
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There are many search engines besides the Search alot service available
on the Web. Here are the links for some other popular ones:
AltaVista
(www.altavista.com)
Northern
Light
(www.northernlight.com)
Excite (www.excite.com)
Google
Yahoo.
There may be minor differences in the details of their use, most of these
engines behave in a similar way, accepting a list of keywords from you and
returning a list of documents that contain those keywords. Keep in mind that
if you don't find the results you're looking for in one search engine, try
another because each search engine analyzes the Web a different way.
• Search engines can access a broad range of material on the Web,
depending on search strings used. Thus, unsupervised use of
search engines by students can lead to access of inappropriate
material.
• If you intend to use search engines directly in your classes . There
are
some
search
engines
try
to
prevent
this.
Searchenginewatch.com has a list of the search engines on their
web site that attempt to screen inappropriate material.
• Also, you may find it useful to warn your students that it is possible
to go back and find out from the computer which files and addresses
have been accessed by the Web browser on that computer .
Directories
• A directory is built by someone looking at a web
site to determine if it's worthy of being added to
their database and if so, under what category it
should fall. Regular search engines are not so
discerning. As you might suspect, directories
don't cover as much of the Web as a search
engine, and there is the potential element of
human bias in categorization.
• Many directories have search tools to help you
find specific items within each category.
• For Example Looksmart and yahoo.
COPY RIGHT LAWs
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3.
Something appears on the Internet does not mean that it is legal
for you to copy it.
The law generally holds that it is your responsibility to determine
the legality of copying something, irrespective of whether the
source from which you copy it has broken the law or not.
A related point to keep in mind is that when, as in the case of the
Tutorial, someone gives you permission to use their material, this
permission does not extend to material that may be accessed by
a link from the original material. The question of how material
accessed in an external link may be used clearly must be put to
its owner.
4. You should Notice carefully the distinction:
you may usually insert a link to someone
else's Web material in your pages without
restriction; the issue of ownership
becomes important only when you attempt
to download material from other Web sites
and incorporate it directly into your Web
material.
Cyber Laws in India
• In May 2000, both the houses of the Indian Parliament passed the
Information Technology Bill. The Bill received the assent of the
President in August 2000 and came to be known as the Information
Technology Act, 2000. Cyber laws are contained in the IT Act, 2000.
This Act aims to provide the legal infrastructure for e-commerce in
India.
The Act states that unless otherwise agreed, an acceptance of
contract may be expressed by electronic means of communication
and the same shall have legal validity and enforceability (DIT).
Advantages of Cyber Laws
• The IT Act 2000 provides ways to deal with cyber crimes. We need
such laws so that people can perform purchase transactions over
the Net through credit cards without fear of misuse. In view of the
growth in transactions and communications carried out through
electronic records, the Act seeks to empower government
departments to accept filing, creating and retention of official
documents in the digital format. The Act has also proposed a legal
framework for the authentication and origin of electronic records /
communications through digital signature (DIT).
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From the perspective of e-commerce in India, the IT Act 2000 and its provisions contain many positive
aspects. Firstly, the implications of these provisions for the e-businesses would be that email would now be a
valid and legal form of communication in our country that can be duly produced and approved in a court of
law.
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Companies shall now be able to carry out electronic commerce using the legal infrastructure . Digital
signatures
have
been
given
legal
validity
and
sanction
in
the
Act.
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The Act throws open the doors for the entry of corporate companies in the business of being Certifying
Authorities
for
issuing
Digital
Signatures
Certificates.
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The Act now allows Government to issue notification on the web thus heralding e-governance.
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The Act enables the companies to file any form, application or any other document with any office, authority,
body or agency owned or controlled by the appropriate Government in electronic form by means of such
electronic
form
as
may
be
prescribed
by
the
appropriate
Government.
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The IT Act also addresses the important issues of security, which are so critical to the success of electronic
transactions. The Act has given a legal definition to the concept of secure digital signatures that would be
required to have been passed through a system of a security procedure, as stipulated by the Government at a
later
date.
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Under the IT Act, 2000, it shall now be possible for corporates to have a statutory remedy in case if anyone
breaks into their computer systems or network and causes damages or copies data. The remedy provided by
the
Act
is
in
the
form
of
monetary
damages,
not
exceeding
Rs.
1
crore.
( Department Of Information technology.)
Ways to speedup download time:
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When there is an addition of graphic ,audio and video files to a web site and if any
user wants to access this website then there will be delay in downloading.
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Cut out unnecessary HTML such as comments , font changes and table elements that are
needed.
Use cascading Style Sheet to control appearance rather than changing fonts and
appearance on every page.
Always use correct width and height attributes in image tags.
Resize and resample the graphics.
Lower the quality settings of JPEG files.
Use GIFs instead of JPGs when possible.
Lower the resolution of a high resolution graphic.
Display a low-resolution verson of a graphic while downloading.
Create thumbnail.
Display alt text.
Split content into more pages.
Avoid unnecessary use of multimedia content like java applets, movies,
images,animation and other elements
Uses of the Internet:
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On-line communication
Software Sharing
Exchange of views on topic of common interest
Posting of information of general interest
Product promotion
Feed back about products
Customer support service
On-line journals and magazines
On- line shopping
World wide video conferencing
Education and training
Entertainment
Banking and financial transactions
What user expect to find on
website:
The user should be involved in clicking and entering there choices rather than being static watchers. The
level of success is based on the level of user satisfaction:
•
1. Users do not enjoy getting lost, having system lockup or being tricked.
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2. Users like to be able to click any where at any time and get what they want.
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3. Users enjoy being in control and having easy navigation and multiple choices.
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4. User demand fast loading pages and go elsewhere if they do not get them.
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5.User cannot see image maps or graphics due to technology limitations.
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6. Users often dislikes clumsy frames and bothersome drop down menus.
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7. User likes hyper text links but hate entry tunnels like “Click here to enter”.
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8. Users often do not have 256 colors so many graphics look bad in just 16.
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9. Users say they return to site that treat them well as a web customer.
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10. Users prefer to click through multiple short pages than wait for long one.
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11. Users love pictures prefer being told how big they are so they can deside whether to load them or
not.
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12. Users have little idea about how internet magic works but know instantly which sites they prefer and
which they will bookmark for for later viewing.
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13. Users know the Internet is not Television ,but still expect the web to grab their attention in engaging
and interactive way.
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14. Users enjoy being part of an online community so chat features bolted on to a site can triple session
lengths, double Kb per user and page impression downloads per session , bolster visit frequency by
over 50 % , and work a site’s servers a great deal harder. Most web users are simply not Cookie
Monsters and are turned off if they are constantly being bombard with them.
Some Important Internet Terms
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Archie : A program used to search files at FTP sites .There are currently 30
Archie servers in the world.
Web site : Collection of web pages.
Home page: The main page of a web site.
Host : A computer system that is the source of network services.
HTTP: The client server protocol upon which the www is based.
IP : Allows a packet to travel through multiple networks on the way to its destination.
IP Address: A unique number assigned to every computer directly connected to internet.
Browser : System Program that allows you to surf the web.
Site : A place on the Internet. Every web page has a location where it resides, which is
called its site.
Spam : Spamming is sending the message to a large number of users, usually to advertise
something means the Internet version of junk mails.
Surfing: The process of “looking around” the Internet.
URL : Address of web site.
WWW : Is a universal mass of web pages connected together through links.
WIRELESS TECHNOLOGIES
• Over recent years, the market for wireless
communications has enjoyed tremendous
growth. Wireless technology now reaches
vertually every location on the face of the
earth.
Types of wireless
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Wireless Local Area Networks
802.11b (Wireless Eathernet)
802.11a , HiperLAN ii , and homeRF
Fixed Broadband Wireless Multiservice Wide Area Networks.
Mobile Wireless
Wireless Personal Area Networks
Based on Bluetooth technologies :Bluetooth in its most basic form is cable
replacement. Where cable now connect many devices, Awireless bluetooth
connection will provide low cost wireless communications and networking between
PCs, mobile phones and other devices. Bluetooth is an RF (radio frequency)
technology for short- range wireless networking.
WAP
• WAP is wireless application protocol which
allows web-like content to be sent to
mobile devices.
Dr. Veer Sain Dixit
Deptt. Of Computer Science
ARSD College, University of Delhi
Email: [email protected]