Transcript Unit-1_Internet

Smt. K. B. Parekh College of Comp. Science
Area Under Discussion:
Internet Technology & Java
Primed by:
Laukik H. Gondalia
Assisted by:
Miss. Hemangi Doshi
Index
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2.
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Internet Intranet, Extranet
Internet Applications
E-mail Protocols
Introduction to TCP/IP, DNS, MIME types
Search Engines
Introduction to Subject
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Internet technology and Java is meant for the
student’s development in the field of
Internet.
It assist you in getting information about
how you can connect to the world of
Internet by providing you with its use and
applications
It also provides the necessary knowledge
about various components and mechanism
used in developing the internet.
What is Internet?
A worldwide system of interconnected
networks and computers is known as
internet.
 The Internet use the standard Internet
Protocol Suite (TCP/IP) to serve billions
of users worldwide.
 Most traditional communications media
including telephone, music, film, and
television are being reshaped or redefined
by the Internet.
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It is a hardware and software
infrastructure that provides connectivity
between computers.
Internet
What is Intranet?
An intranet is a private computer
network that uses Internet Protocol
technologies to securely share any part of
an organization's information or
operational systems within that
organization.
 The term is used in contrast to internet, a
network between organizations, and
instead refers to a network within an
organization
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Uses of Intranet
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Intranets are also being used as corporate
culture-change platforms. For example, large
numbers of employees discussing key issues
in an intranet forum application could lead
to new ideas in management, productivity,
quality, and other corporate issues.
Intranets are being used to deliver tools and
applications, e.g., collaboration (to facilitate
working in groups and teleconferencing) or
difficult corporate directories
Benefits of Intranet
Workforce productivity: Intranets can
help users to locate and view information
faster and use applications relevant to
their roles and responsibilities.
 Time: Intranets allow organizations to
distribute information to employees on an
as-needed basis.
 Communication: Intranets can serve as
powerful tools for communication within
an organization.
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Cost-effective: Users can view information
and data via web-browser rather than
maintaining physical documents such as
procedure manuals, internal phone list and
requisition forms.
 Enhance collaboration: Information is
easily accessible by all authorized users,
which enables teamwork.
 Cross-platform capability: Standardscompliant web browsers are available for
Windows, Mac, and UNIX.
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What is Extranet?
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An extranet is a computer network that allows
controlled access from the outside, for specific
business or educational purposes. An extranet can be
viewed as a public network.
A Web site for customers rather than the general
public.
It can provide access to research, current inventories
and internal databases, virtually any information that
is private and not published for everyone.
An extranet uses the public Internet as its
transmission system, but requires passwords to gain
entrance.
Access to the site may be free or require payment for
some or all of the services offered.
Merits & Demerits of Extranet
Advantages
 Exchange large volumes of data
 Share product catalogs exclusively with trade
partners
 Collaborate with other companies on joint
development efforts
Disadvantages
 Extranets can be expensive to implement
and maintain within an organization.
 Security of extranets can be a concern when
hosting valuable or proprietary information.
Internet Applications
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WWW
E-mail
FTP
IRC
Web chat
Newsgroup
Usenet
BBS
Net Meeting
Video Conferencing
WWW (World wide web)
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The World Wide Web, abbreviated as WWW and
commonly known as the Web, is a system of
interlinked hypertext documents accessed via the
Internet.
The WWW is a network of computers all over the
world. The WWW is most often called the Web.
The computers on the Web communicate using
standard protocols and languages.
The W3C (The World Wide Web Consortium) are
making the rules and standards for the Web.
With a web browser, one can view web pages that
may contain text, images, videos, and other
multimedia and navigate between them via hyperlinks.
E-mail
Electronic mail, commonly called email or email, is a method of exchanging digital messages
across the Internet or other computer networks.
 Originally, email was transmitted directly from
one user to another computer. This required both
computers to be online at the same time, a la
instant messaging.
 Today's email systems are based on a store-andforward model. Email servers accept, forward,
deliver and store messages. Users no longer need
be online simultaneously and need only connect
briefly.
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Email Delivery Method
FTP
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File Transfer Protocol (FTP) is a
standard network protocol used to copy a
file from one host to another over a TCP/IPbased network, such as the Internet.
FTP is built on a client-server architecture
and utilizes separate control and data
connections between the client and server.
FTP users may authenticate themselves
using a clear-text sign-in protocol but can
connect anonymously if the server is
configured to allow it.
IRC (Internet relay chat)
CUI based IRC
GUI based IRC
IRC with webcam
IRC without webcam
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Internet Relay Chat (IRC) is a form of realtime Internet text messaging (chat) or
synchronous conferencing.
It is mainly designed for group communication in
discussion forums, called channels, but also allows
one-to-one communication via private message as
well as chat and data transfers via Direct Clientto-Client.
An Internet system that enables users to take
part in on-line discussions.
History of IRC
IRC was created by Jarkko Oikarinen in
August 1988 to replace a program called
MUT (Multi User Talk) on a BBS called
Oulu Box in Finland.
 Oikarinen found inspiration in a chat
system known as Bitnet Relay, which
operated on the BITNET.
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Web Chat
A web chat is a system that allow users to
communicate in real time using easily
accessible web interfaces.
 It is a type of internet online chat
distinguished by its simplicity and
accessibility to users who do not wish to
take the time to install and learn to use
specialized chat software.
 This trait allows users instantaneous access
and only a web browser is required to chat.
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Newsgroup
A newsgroup is a warehouse usually within the
Usenet system, for messages posted from many users
in different locations.
 The term may be confusing to some, because it is
usually a discussion group. Newsgroups are technically
distinct from, but functionally similar to, discussion
forums on the World Wide Web.
 Despite the advent of file-sharing technologies such
as BitTorrent, as well as the increased use of blogs,
formal discussion forums, and social networking sites,
coupled with a growing number of service providers
blocking access to Usenet (see main article),
newsgroups continue to be widely used.
 Newsreader software is used to read newsgroups.
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Newsgroup Software
Types of Newsgroup
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The newsgroup is focused on a particular
topic of interest.
Some newsgroups allow the posting of
messages on a wide variety of themes,
regarding anything a member chooses to
discuss as on-topic, while others keep more
strictly to their particular subject, frowning
on off-topic postings.
The news admin (the administrator of a
news server) decides how long articles are
kept on his server before being expired
(deleted)
Usenet
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Usenet is a worldwide distributed Internet
discussion system. It developed from the
general purpose UUCP (Unix to Unix
Copy)architecture of the same name.
Duke University graduate students Tom
Truscott and Jim Ellis conceived the idea in
1979 and it was established in 1980.
Users uploads and downloads letters,
documents (called articles or posts, and
collectively termed news).
BBS
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BBS stands for Bulletin Board System.
A Bulletin Board System, or BBS, is a
computer system running software that
allows users to connect and log in to the
system using a terminal program.
Once logged in, a user can perform functions
such as uploading and downloading software
and data, reading news and bulletins, and
exchanging messages with other users,
either through electronic mail or in public
message boards.
Many BBSes also offer on-line games, in
which users can compete with each other,
and BBSes with multiple phone lines often
provide chat rooms, allowing users to
interact with each other.
 In recent years, BBS is also indicated as
Bulletin Board Service
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Net Meeting
Net meeting is a conferencing client developed by
Microsoft that allows users to interact in real time
over the internet. Most people call it a "video
conferencing client“.
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◦ A Chat client, similar to AOL Instant Messenger
◦ An Audio and Video conferencing client
◦ A Whiteboard, which is a shared drawing space where
people can collaborate in real time.
◦ Application Sharing, where you can choose to share an
application you are running with others in your
conference. Note here that while other users will need to
have Net meeting installed, they do not need to have a
copy of the application you are sharing installed.
◦ A file transfer application for sending files
Video Conference
A videoconference or video conference (also
known as a videoteleconference) is a set of
interactive telecommunication technologies which
allow two or more locations to interact via twoway video and audio transmissions simultaneously.
 It has also been called 'visual collaboration' and is
a type of groupware.
 Videoconferencing differs from videophone calls
 It is an intermediate form of video telephony, first
deployed commercially by AT&T during the early
1970s using their Picturephone technology.
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E-mail Protocols
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There are various types of E-mail protocols. They are
as follows:
◦ SMTP (Simple Mail Transfer Protocol
◦ POP3 (Post Office Protocol)
◦ IMAP (Internet Message Access Protocol)
◦ MAPI (Messaging Application Programming Interface)
SMTP Protocol
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SMTP is a text-based protocol, in which a
mail sender communicates with a mail
receiver by issuing command strings and
supplying necessary data over a reliable
ordered data stream channel i.e.(TCP)
connection.
An SMTP session consists of commands
originated by an SMTP client (sender) and
corresponding responses from the SMTP
server (receiver).
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A session may include zero or more SMTP
transactions. An SMTP transaction consists of
three command/reply sequences. They are:
◦ MAIL command, to establish the return address,
a.k.a. Return-Path
◦ RCPT command, to establish a recipient of this
message.
◦ DATA to send the message text.
POP Protocol
Post Office Protocol (POP) is an
application-layer Internet standard
protocol used by local e-mail clients to
retrieve e-mail from a remote server over
a TCP/IP connection.
 The POP protocol has been developed
through several versions, with version 3
(POP3) being the current standard. POP3
is used for most webmail services such as
Gmail and Yahoo! Mail.
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IMAP
The Internet Message Access
Protocol (IMAP) is one of the two
most prevalent Internet standard
protocols for e-mail retrieval.
 IMAP is an Application Layer Internet
protocol that allows an e-mail client to
access e-mail on a remote mail server. The
current version, IMAP version 4 revision 1
(IMAP4rev1), is defined by RFC 3501.
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Internet Protocols
Various types of Internet Protocols are in
use in recent time.
 They are as follows:
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◦ TCP/IP (Transmission Control
Protocol)/(Internet Protocol)
◦ DNS( Domain Name System)
◦ MIME(Multipurpose Internet Mail Extensions)
TCP/IP
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TCP is a connection-oriented transport
service; it provides end-to-end reliability,
resequencing, and flow
control. TCP enables two hosts to establish a
connection and exchange streams of data,
which are treated in bytes.
The delivery of data in the proper order is
guaranteed.
TCP can detect errors or lost data and can
trigger retransmission until the data is
received, complete and without errors.
IP (internet protocol)
IP provides communication between hosts
on different kinds of networks (i.e., different
data-link implementation such as Ethernet
and Token Ring).
 It is a connectionless, unreliable packet
delivery service.
 Connectionless means that there is no
handshaking, each packet is independent of
any other packet.
 It is unreliable because there is no guarantee
that a packet gets delivered
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DNS
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The Domain Name System (DNS) is a
hierarchical naming system built on a
distributed database for computers, services,
or any resource connected to the Internet
or a private network. It associates various
information with domain names assigned to
each of the participating entities.
Most importantly, it translates domain names
meaningful to humans into the numerical
identifiers associated with networking
equipment for the purpose of locating and
addressing these devices worldwide.
MIME
Multipurpose Internet Mail Extensions (MIME),
documented in RFC 1521 and RFC 1522, defines
the standard representation for "complex"
message bodies.
 A "complex" message body doesn't conform to
the default of a single, human-readable, ASCII mail
message.
Examples of "complex" message bodies include
messages with embedded graphics or audio clips,
messages with file attachments, messages in Japanese
or Russian, or signed messages. I.e. now the mail may
have MIME provides extensions, allowing some new
uses of electronic mail;
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Messages now may have:
•Multiple objects within a single message,
•Text with unlimited line length or overall
length
•Character sets other than 7-bit ASCII
•Multi-font messages
•Binary or application-specific files
•Images, audio, video and multi-media
messages
Search Engines
A search engine is an information retrieval
system designed to help find information stored
on a computer system.
 The search results are usually presented in a list
and are commonly called hits.
 Search engines help to minimize the time
required to find information and the amount of
information which must be consulted, akin to
other techniques for managing information
overload.
 The most public, visible form of a search engine is
a Web search engine which searches for
information on the World Wide Web.
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Categories of Search Engines
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Search Engines are categorized in
following types:
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By Content/Topic
By Model
By Information Type
Acquired Search Engine
◦ Only first type of search engine is mentioned, for more info please
contact either tutor or me.
By Contents
General: Ask.com, Bing, Google,Yahoo
 Accountancy: IFACnet(International
Federation of Accountants (IFAC)
 Business: Business.com, GlobalSpec
 Enterprise: AskmeNow, Microsoft, IBM,
Teratext
 Mobile: Taganode Local Search Engine, Taptu
 Job: Bixee.com, Dice.com, Monster.com
 Legal: West law, Quick Law, etc.
 Medical: Bing Health, Webster, etc
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Working of Search Engines
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A web search engine is designed to search
for information on the World Wide Web and
FTP servers.
The search results are generally presented in
a list of results and are often called hits.
The information may consist of web pages,
images, information and other types of files.
Some search engines also mine data available
in databases or open directories.
Best Search Tips
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Most search engines default to Boolean AND logic. To
create a search that will retrieve Web pages containing all of
your search terms, type the words with a space in between
them.
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Use a plus sign (+) to further focus a Boolean AND
search. Example: +desert +horticulture
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Include synonyms or alternate spellings in your
search statements and connect these words with
Boolean OR logic. Example: college OR university
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For a Boolean NOT search, place a minus sign (- ) in
front of the word you want to exclude from your
search results. Example: apple -computer
General Search Tips
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If you're not sure how to use a particular
search engine, read the Help pages.
Check your spelling.
Take advantage of capitalization if the search
engine is case sensitive. Hint: Google is not
case sensitive.
If your results are not satisfactory, repeat the
search using alternative words.
Try different sources to diversify your
results. Sources can include subject
directories, research sites such as Google
Scholar