Nilesh U. SambheAssistant Professor, Department Of Computer Technology,

Yeshwantrao Chavan College Of Engineering, Nagpur

The Internet and How It Works

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OUTLINE• Internetworking

• Connections

• Internet Services

• The World Wide Web and HTML

• Dynamic Web Pages and XML

• Multimedia on the WEB

Tools For the World Wide Web

• Web Servers

• Web Browsers

• Search Engines

• Web Page Makers and Site Builders

• Plug-ins and Delivery Vehicles

• Beyond HTML

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HISTORY

ARPANET

• The Internet was created in 1969 by the Advanced Research Projects Agency.

• ARPA was part of the U.S. Department of Defense.

• The ARPANET grew as it networked universities, military sites, and government

agencies.

• In 1983, the network has several hundred computers on few LAN’s

• In 1985, National Science Foundation (NSF) used ARPANET to connect

supercomputers and computer science centers.

• Also increases the bandwidth from 56kbps to T1(24 leased lines of 56 kbps)

• management of the ARPANET officially passed to the NSF in 1989.

• Commercial use of the internet began in 1992.

• Around 40% of the world population has an internet connection today

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INTERNETWORKING

Networking basics

• Two or more computers connected to each other make a network.

• A local network is called a Local Area Network (LAN).

• Distant LAN’s can be connected via phone lines or another medium to

form a Wide Area Network (WAN).

• LAN’s, WAN’s, and individual computers can also connect to the

internet through a server.

• A server is permanently connected to the internet through a

high-bandwidth physical connection.

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INTERNETWORKING

• TCP/IP is the protocol used for communicating on the internet

• TCP is Transmission Control Protocol

• IP is the Internet Protocol

• In 1983 the Domain Name System (DNS) was established to assign

names and addresses to computers which were linked to the internet.

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INTERNET ADDRESSES

• ADDRESS SYNTAX

• Internet addresses use the following syntax:

[PROTOCOL]://[DOMAIN NAME]/[PATH]/[FILE NAME]

( HTTP://WWW.YCCE.EDU) FOR EXAMPLE

• The server directory path and file name are often left off.

• The protocol usually does not need to be typed.

• The protocol is also often hidden, such as

• mailto

• news

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INTERNET ADDRESSES

• TOP-LEVEL DOMAINS (TLDS)

• The current Domain Name System (DNS) was developed in 1983.

• TLDS were established for various categories.

• The TLD is part of the domain name, such as

• .Com

• .Net

• .Gov

• .Mil

• .Edu

• Two-letter country codes

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DOMAIN NAME SYSTEM ( DNS)

• In 1998 (ICANN) Internet Corporation For Assigned Names And Numbers

was set up to oversee the DNS.

• In 2000, ICANN approved seven new TLDS:

• Aero(Air-Transport) info(Unrestricted use)

pro(Accountants, lawyers)

• Biz(Business) museum(museums)

• Coop(Cooperatives) name(For individuals)

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IP ADDRESSES AND DATA PACKETS

• The internet transmits data using the transmission control protocol (TCP).

• Data is broken up into packets.

• The internet protocol (IP) transmits the packets.

• Packets can travel along various paths and are reassembled at the

receiving end.

• Destinations are identified by numeric IP addresses such as:

140.174.162.10

• Domain name servers look up these addresses and then convert

them to real IP address.

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CONNECTIONS

• To connect to the internet, a computer or network needs

• A data connection to a server

• the data connection can be wireless or a land line.

• you usually need an account with the server.

• most people access a server through an internet service provider

(ISP).

• TCP/IP software

• your operating system may need to be configured to connect to

the server and use TCP/IP software.

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CONNECTIONS

• Internet software includes

• E-MAIL PROGRAMS

• WEB BROWSERS

• FTP SOFTWARE

• NEWS READERS

• ISP ( INTERNET SERVICE PROVIDERS) SOFTWARE

• PPP - (POINT TO POINT) for dialing up

• TCP/IP for sending and receiving

• POP (POINT OF PRESENCE) - local telephone number

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BANDWIDTH BOTTLENECK

• Bandwidth is how much data, you can send from one computer to

another in a given unit of time

• The bandwidth bottleneck

• Bandwidth is measured in bits per second (bps).

• Available bandwidth greatly affects how a person can use the

internet.

• Users with slow connections will have a difficult time using multimedia

over the internet.

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BANDWIDTH BOTTLENECK

• To accommodate low bandwidth users

• Compress data when possible.

• Take advantage of the browser’s cache.

• Design each multimedia element to be efficiently compact.

• Design alternate sites for low- and high-bandwidth Users.

• Consider using streaming technology.

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INTERNET SERVICES

• Services include HTTP, FTP, TELNET(working from remote computers),

USENET(For participating in discussion group), SMTP( for sending mail).

• Multipurpose internet mail extensions (MIME)-types

• files used online must conform to internet protocols.

• data types are identified using MIME-types.

• file types must be recognized by servers to be used on the internet.

• When the server sends a document to a browser, it also sends its MIME

type. This information helps the browser to know what kind of file it is

(HTML, ZIP, JPEG image, etc…) and what to do with it (display it, save

it on the disk, launch a configured application to read it, etc…)

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THE WORLD WIDE WEB AND HTML

• Web history

• Tim Berners-Lee of CERN (the European particle physics laboratory)

developed the web’s hypertext system in 1989.

• The Hypertext Transfer Protocol (HTTP) was designed as a means

for sharing documents over the internet.

• The Hypertext Markup Language (HTML) is the markup language

of the web.

• Cross-platform compatibility was a design goal.

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HTTP

• The Hypertext Transfer Protocol ( HTTP) provided rules for a simple

transaction:

• Establishing a connection

• Requesting that a document be sent

• Sending a document

• Closing the connection

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HTML

• The HTTP protocol also required a simple document format called HTML

(hypertext markup language) for presenting text and graphics.

• The HTML document can contain hotlinks which a user can click to jump to

another location.

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DYNAMIC WEB PAGES AND XML

• 1. Advanced tools can be used to make a web page Dynamic.

• Dynamic Technologies include

• Cold Fusion (CFM)

• Hypertext Preprocessor (PHP)

• Active Server Pages (ASP)

• Java Script And Java Applets

• Dynamic pages work in conjunction with database applications to

look up data.

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(XML) EXTENSIBLE MARKUP LANGUAGE

• XML goes beyond HTML and is the next step in developing web pages.

• This markup language allows developers to define their own styles and

elements.

• It allows you to Create your own tags to describe what the data means.

• Whether or not XML is the future of web design is still somewhat

questionable.

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MULTIMEDIA ON THE WEB

To design and make effective multimedia for the environment

• Developers need to understand how to create and edit elements of

multimedia and also how to deliver it for HTML browsers and plug-

in/player vehicles.

• The number of new users of the web will create a greater need for high

quality, compelling content, and reasonably quick presentations.

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Tools For the World Wide Web

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WEB SERVERS

• The “server” is actually software.

• various servers are available that run on various platforms.

• the most common server packages include

• Apache

• Microsoft Internet Information Services (IIS)

• IPLANET

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WEB SERVERS

• The server plays a pivotal role in content delivery.

• The speed and capacity of the server has a major effect on

performance.

• This is especially true when the server is delivering streaming

content.(RealAudio or shockwave/Flash or QuickTime video)

• Speed and capacity is affected by the server hardware.

• A growing number of software provide the webservers of varying

strength and capacity and for variety of platforms which meets

requirements of HTTP.

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WEB BROWSERS

• Web browser (commonly referred to as a browser) is a software

application for retrieving, presenting, and traversing information

resources on the World Wide Web. An information resource is

identified by a Uniform Resource Identifier (URI/URL) and may be a

web page, image, video or other piece of content The most common

web browsers are

• Internet Explorer

• Netscape Navigator

• Some alternate browsers, are

• Opera

• Mozilla

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WEB BROWSERS

• Web browsers have increasingly grown to support plug-in

technologies such as FLASH and java.

• Web browsers often vary from the HTML standards.

• support for features such as Cascading Style Sheets (CSS) is

inconsistent.

The majority of visitors to your web site will be using Internet

Explorer Or Netscape with plug-ins. You should be sure that

your content looks good in both of them.

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2016 Chrome IE Firefox Safari Opera

August 72.4 % 5.2 % 16.8 % 3.2 % 1.1 %

WEB PAGE MAKERS AND SITE BUILDERS

• Learn HTML

• Although site building tools seem to remove the need to learn HTML,

some knowledge is still important.

• An HTML document can be created or edited using only a text editor.

• Site building tools

• Various tools help you create web pages in a WYSIWYG(What you

See Is What you Get) editing environment.

• They provide more power and more features specifically geared to

exploiting HTML.

• The markup created by editors is often complicated and bloated.

• Inspite of this, these tools can be timesavers. 27

WEB PAGE MAKERS AND SITE BUILDERS

• Common site building tools include

• Adobe Go live

• Macromedia Dreamweaver

• Microsoft FrontPage

• Myrmidon

• Netscape Composer

• HTML translators

• Many programs such as word processors incorporate HTML

translators.

• These are built into many word processing programs , so we can

export a word –processed documents with its text styles and layout

converted to HTML tags for header, bolding, underlying, indenting

and so on.

• The markup created by translators is often bloated and proprietary.

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WEB BROWSERS AND PLUG-INS

• Plug-ins and delivery vehicles

• Plug-ins add capabilities to the web browser.

• plug-ins are also sometimes called helper applications.

• If your content requires a plug-in, don’t forget that users must have

the plug-in installed.

• provide a link to help the user obtain the plug-in.

• decide whether requiring a plug-in is worthwhile.

• Types of plug-ins include

• Text (such as Adobe Acrobat Reader)

• Images (such as Macromedia Shockwave) which allows the

display of vector graphics. 29

WEB BROWSERS AND PLUG-INS

• Plug-ins

• Sound

• Plug-ins such as Real player, QuickTime, and Windows

Media Player can play music.

• D)Animation, video, and presentation

• Real player, QuickTime, and Windows Media player also

play animations and video.

• Flash and Shockwave are used for animation and

presentation.

• Microsoft PowerPoint can be used for online presentations

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VAUGHN’S BANDWIDTH RULE

Bandwidth = satisfaction

File size

• Satisfaction with the internet is a function of connection speed and the

size of the data elements accessed

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BEYOND HTML

• Programming technologies can be used for online content delivery,

such as

• COMMON GATEWAY INTERFACE (CGI) PROGRAMMING

• PERL

• JAVA

• JAVASCRIPT

• PHP

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BEYOND HTML

• You can interact online with conferencing tools such as

• BEING THERE

• CU-SEEME from white pine

• LIVEMEDIA from Netscape

• NETMEETING from Microsoft

• 3-D worlds

• Virtual Reality Modeling Language (VRML)

• Macromedia Director/Shockwave Player

• Apple QuickTime

• Java33

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