mastering the internet, xhtml, and javascript chapter 1 overview of the internet

Mastering the Internet, Mastering the Internet, XHTML, and JavaScriptXHTML, and JavaScript

Chapter 1Chapter 1

Overview of the InternetOverview of the Internet

2Chapter 1 - Overview of the Internet

OutlineOutline Goals and ObjectivesGoals and Objectives Chapter headlinesChapter headlines IntroductionIntroduction Internet and WWWInternet and WWW Client/Server ModelClient/Server Model Diagnostic commandsDiagnostic commands Evolution of InternetEvolution of Internet TransmissionTransmission IP Addresses and URLsIP Addresses and URLs Internet Domain NamesInternet Domain Names

E-mail addressesE-mail addresses File ProtocolsFile Protocols File Compression and File Compression and

DecompressionDecompression Intranets and ExtranetsIntranets and Extranets Connecting to the InternetConnecting to the Internet Types of ModemsTypes of Modems Internet ToolsInternet Tools SummarySummary


Goals and ObjectivesGoals and Objectives GoalsGoals

Understand and master some of the basic concepts of Internet Understand and master some of the basic concepts of Internet and World Wide Web, to be able to use them effectively in and World Wide Web, to be able to use them effectively in ordinary life, as well as in professional activitiesordinary life, as well as in professional activities

ObjectivesObjectives Client/Server ModelClient/Server Model Data and file transmissionData and file transmission URLs and IP addressesURLs and IP addresses E-mail addressesE-mail addresses File protocols, compression and decompressionFile protocols, compression and decompression Intranets and ExtranetsIntranets and Extranets Internet connectionsInternet connections ModemsModems


Chapter HeadlinesChapter Headlines 1.1 1.1 IntroductionIntroduction

The Internet is dubbed as a new mode of transportationThe Internet is dubbed as a new mode of transportation 1.2 1.2 The Internet and the World Wide WebThe Internet and the World Wide Web

The web is the section of internet that features multimedia The web is the section of internet that features multimedia capabilitiescapabilities

1.3 1.3 Internet JargonInternet Jargon Learn the internet jargon as you goLearn the internet jargon as you go

1.4 1.4 Client Server ModelClient Server Model This model allows two networked computers to talk to each This model allows two networked computers to talk to each

otherother 1.51.5 Client/Server Diagnostic CommandsClient/Server Diagnostic Commands

These are useful to probe communication with a serverThese are useful to probe communication with a server


Chapter HeadlinesChapter Headlines 1.61.6 Evolution of the internet and the World Wide WebEvolution of the internet and the World Wide Web

The internet has been evolving since the 1960sThe internet has been evolving since the 1960s 1.71.7 Transmission across the InternetTransmission across the Internet

The TCP/IP protocol and its packets are central to internet The TCP/IP protocol and its packets are central to internet useuse

1.81.8 IP Addresses and URLsIP Addresses and URLs Computers use IP addresses and humans use URLsComputers use IP addresses and humans use URLs

1.91.9 Internet domain NamesInternet domain Names An internet domain is a part of a URLAn internet domain is a part of a URL

1.101.10 E-mail AddressesE-mail Addresses An E-mail address extends the naming scheme of a domain An E-mail address extends the naming scheme of a domain

namename


Chapter HeadlinesChapter Headlines 1.11 1.11 File protocols on the InternetFile protocols on the Internet

Formats and rules of exchanging files on the InternetFormats and rules of exchanging files on the Internet 1.12 1.12 File Compression and DecompressionFile Compression and Decompression

Keeping file size small to speed up downloads and uploadsKeeping file size small to speed up downloads and uploads 1.13 1.13 Intranets and ExtranetsIntranets and Extranets

Companies use these private networks for security reasonsCompanies use these private networks for security reasons 1.14 1.14 Connecting to the InternetConnecting to the Internet

Companies use T lines while homes use dial-up connectionCompanies use T lines while homes use dial-up connection 1.15 1.15 Types of ModemsTypes of Modems

Analog (phone), cable, and DSL modemsAnalog (phone), cable, and DSL modems 1.16 1.16 Internet ToolsInternet Tools

These tools depend on you interestThese tools depend on you interest


IntroductionIntroduction

The internet provides an The internet provides an instant mode of instant mode of information and communicationinformation and communication

Internet had more users in its first five years than Internet had more users in its first five years than telephone did in its first thirty yearstelephone did in its first thirty years

E-mails already outnumbers regular mailsE-mails already outnumbers regular mails


Internet and World Wide WebInternet and World Wide Web Internet is a Internet is a network of networksnetwork of networks It is known as It is known as information information

superhighwaysuperhighway Internet Internet links powerful serverslinks powerful servers in in

every part of the worldevery part of the world World Wide Web (WWW) is the World Wide Web (WWW) is the

driving forcedriving force of internet that features of internet that features multimedia capabilities, such as, multimedia capabilities, such as, text, audio, video, graphics, and text, audio, video, graphics, and imagesimages

The heart of internet is its The heart of internet is its dynamic dynamic nature and randomness of nature and randomness of informationinformation


Client/Server ModelClient/Server Model Client/Sever model uses two Client/Sever model uses two

computer programs installed computer programs installed on separate, but networked, on separate, but networked, computers located at computers located at different locationsdifferent locations

The client requests services The client requests services from the serverfrom the server

Multiple clients can access a Multiple clients can access a server concurrentlyserver concurrently


Two-tier/Three-tier ArchitectureTwo-tier/Three-tier Architecture

Client/Server databases Client/Server databases are used extensively on are used extensively on web.web.

Two-tier architectureTwo-tier architecture is is the most common the most common model.model.

In three-tier model, a In three-tier model, a middle server is added middle server is added between the database between the database and the client for and the client for security purposes.security purposes.


Client/Server Diagnostic CommandsClient/Server Diagnostic CommandsThe three important commands are:The three important commands are:

1.1. fingerfinger: Allows you to find who is currently logged into : Allows you to find who is currently logged into a given host or whether a particular user is logged ina given host or whether a particular user is logged ine.g. – e.g. – finger hostnamefinger hostname

finger username@hostnamefinger username@hostname

2.2. pingping: Allows a client to check whether a server is up : Allows a client to check whether a server is up and runningand runninge.g. – e.g. – ping hostnameping hostname

3.3. tracerttracert: Traces the transmission route of data from : Traces the transmission route of data from client to a serverclient to a servere.g. – e.g. – tracert hostnametracert hostname


Evolution of the InternetEvolution of the Internet Early research on the concept of internet began in Early research on the concept of internet began in

1962 at Advanced Research Project Agency (ARPA)1962 at Advanced Research Project Agency (ARPA) The The sequence of Internet developmentsequence of Internet development is: is:

1960s 1960s ARPANET ARPANET 1970s-1980s 1970s-1980s CSNET, USENET, CSNET, USENET,

BITNET, NSFNET BITNET, NSFNET 1990s 1990s World Wide Web World Wide Web

In 1989, WWW was conceived by Berner-LeeIn 1989, WWW was conceived by Berner-Lee The Web exploded when Mosaic (first graphically-The Web exploded when Mosaic (first graphically-

oriented browser) became available from the NCSA oriented browser) became available from the NCSA Center at the University of Illinois, Urbana-Center at the University of Illinois, Urbana-Champaign in 1992Champaign in 1992


Transmission across the InternetTransmission across the Internet Data, such as Web pages and e-mail messages, are Data, such as Web pages and e-mail messages, are

transmittedtransmitted from one computer to another from one computer to another across the across the InternetInternet via the TCP/IP protocol via the TCP/IP protocol

The The TCP/IP protocolTCP/IP protocol is embedded in TCP/IP software is embedded in TCP/IP software that is part of the OS (operating system) of any computerthat is part of the OS (operating system) of any computer

Each computer on the Internet has a Each computer on the Internet has a unique IP addressunique IP address that is used to identify it. The TCP/IP software uses this that is used to identify it. The TCP/IP software uses this IP address in data transmissionIP address in data transmission


Transmission across the InternetTransmission across the Internet The TCP/IP software The TCP/IP software breaks the databreaks the data to be delivered to be delivered

into TCP packets (similar to letters), into TCP packets (similar to letters), bundlesbundles them, them, labelslabels them with the sender and receiver IP addresses them with the sender and receiver IP addresses (similar to envelopes), and (similar to envelopes), and sends sends them to the them to the receiver’s IP addressreceiver’s IP address

The TCP/IP software of the receiving computer The TCP/IP software of the receiving computer unpacksunpacks the TCP packets (similar to opening an the TCP packets (similar to opening an envelope), envelope), connectsconnects them to construct the original them to construct the original data (such as an e-mail message), and data (such as an e-mail message), and makes it makes it availableavailable for an application program to read (such as for an application program to read (such as an e-mail tool)an e-mail tool)


The InternetThe Internet


IP Addresses and URLsIP Addresses and URLs An IP address is a An IP address is a 32 bit integer32 bit integer represented by four 8-bit represented by four 8-bit

numbers, separated by periodsnumbers, separated by periods A typical IP address is 155.33.227.141A typical IP address is 155.33.227.141 An IP address is An IP address is assigned to one and only one hostassigned to one and only one host A URL (uniform resource locator) is the A URL (uniform resource locator) is the name versionname version of IP of IP

addressaddress A typical URL is A typical URL is http://www.neu.eduhttp://www.neu.edu whose IP address is the whose IP address is the

one given aboveone given above We use URLs because We use URLs because IP addresses are difficult to rememberIP addresses are difficult to remember DNS (DNS (Domain Name SystemDomain Name System) software converts URLs to IP ) software converts URLs to IP

addresses and vice-versa.addresses and vice-versa.


Internet Domain NamesInternet Domain Names URLs are also known as domain namesURLs are also known as domain names Domain name consists of sub-domains (usually less Domain name consists of sub-domains (usually less

than 5)than 5) The first sub-domain is host nameThe first sub-domain is host name The last sub-domain is top-level domain (TLD)The last sub-domain is top-level domain (TLD) Second level domain excludes the host nameSecond level domain excludes the host name Example:Example:

Domain name

www.coe.neu.edu Host name Second level domain name

TLD


Internet Domain NamesInternet Domain Names TLD can also be geographic i.e. country codes, such TLD can also be geographic i.e. country codes, such

as ‘au’ for Australia, ‘uk’ for England, etc.as ‘au’ for Australia, ‘uk’ for England, etc.

The most common top-level domain names areThe most common top-level domain names are .com.com: commercial organization: commercial organization .edu.edu: educational institution: educational institution .gov.gov: government agency: government agency .org.org: nonprofit organization: nonprofit organization .net.net: network service provider: network service provider .mil.mil: U.S. military: U.S. military


E-mail AddressesE-mail Addresses Each user on the internet has a Each user on the internet has a unique e-mail addressunique e-mail address The format of e-mail address is:The format of e-mail address is:

username@second-levelDomainNameusername@second-levelDomainName The username in the format above is selected by the The username in the format above is selected by the

user and it can be a combination of letters, numbers user and it can be a combination of letters, numbers and certain special charactersand certain special characters

Some example e-mail addresses are:Some example e-mail addresses are:[email protected]@neu.edu

[email protected]@[email protected][email protected]@[email protected]


File ProtocolsFile Protocols File protocols determine the File protocols determine the formats and rules of formats and rules of

exchanging filesexchanging files between the server and client between the server and client The file protocols used on the web areThe file protocols used on the web are

http: Allows client to request a webpage from serverhttp: Allows client to request a webpage from server https: Secure http for secure communicationhttps: Secure http for secure communication smtp/pop/imap: Sends an e-mail message to a specified smtp/pop/imap: Sends an e-mail message to a specified

addressaddress nntp: Allows client to read and post messages on nntp: Allows client to read and post messages on

newsgroupsnewsgroups ftp: Allows downloads and uploads for filesftp: Allows downloads and uploads for files telnet: Allows access to a remote computertelnet: Allows access to a remote computer file: Displays a file existing on client local drivefile: Displays a file existing on client local drive


File Compression and DecompressionFile Compression and Decompression File transfer through internet depends on internet File transfer through internet depends on internet

connection speed, file size and server traffic.connection speed, file size and server traffic. File size affects both File size affects both transfer time and disk spacetransfer time and disk space File compression and decompression allow us to File compression and decompression allow us to

control the file sizecontrol the file size File compression softwares, e.g. winzip, use complex File compression softwares, e.g. winzip, use complex

algorithms to decode (decompress) and encode algorithms to decode (decompress) and encode (compress) a file.(compress) a file.

For example, the file “AAAAAAAGGGWZZZZ” can For example, the file “AAAAAAAGGGWZZZZ” can be compressed as “7A3G1W4Z”be compressed as “7A3G1W4Z”

Multiple files can be compressed together to Multiple files can be compressed together to create create archivesarchives that maintain file directory structure that maintain file directory structure


Intranets and ExtranetsIntranets and Extranets Intranet and Extranet are same as internet, the Intranet and Extranet are same as internet, the

difference being in their difference being in their geographical domainsgeographical domains and and level of securitylevel of security they use they use

IntranetIntranet is a network that is contained within an is a network that is contained within an organization. Outside organization. Outside intruders are not allowedintruders are not allowed to to access this networkaccess this network

FirewallsFirewalls are installed around intranets for are installed around intranets for securitysecurity ExtranetExtranet is an organization network that is an organization network that allows access allows access

to outside networksto outside networks Extranet may be viewed as an intermediate network Extranet may be viewed as an intermediate network

between internet and intranetbetween internet and intranet


Intranets and ExtranetsIntranets and Extranets


Connecting to the InternetConnecting to the Internet Internet Service ProvidersInternet Service Providers (ISPs) provide access to the (ISPs) provide access to the

internet by dial-up connection, DSL, or Cable connectioninternet by dial-up connection, DSL, or Cable connection AOL and MSN are ISPs who offer access and contentAOL and MSN are ISPs who offer access and content Phone and cable companies are ISP who offer access Phone and cable companies are ISP who offer access

only. Finding the content is users taskonly. Finding the content is users task Some ISP selection guidelines are:Some ISP selection guidelines are:

Maximum connection speedMaximum connection speed Type of connection (dial-up or broad band)Type of connection (dial-up or broad band) Available help lineAvailable help line Software providedSoftware provided Costs and chargesCosts and charges


Types of ModemsTypes of Modems Modem is a device used to Modem is a device used to transfer data from one transfer data from one

location to another through phone lineslocation to another through phone lines The The types of modemstypes of modems are: are:

Telephone (analog) modemTelephone (analog) modem Cable modemCable modem DSL and ADSL modemDSL and ADSL modem ISDN (digital) modemISDN (digital) modem B-ISDN modemB-ISDN modem Satellite modemSatellite modem Wireless (cellular) modemWireless (cellular) modem


Internet ToolsInternet Tools Internet tools Internet tools allow effective useallow effective use of the internet of the internet These tools are computer programsThese tools are computer programs Some of these tools are Some of these tools are sharewareshareware and the others are and the others are

freewarefreeware The basic internet tools are:The basic internet tools are:

Web browsersWeb browsers Virus scan programsVirus scan programs File compression and decompression programsFile compression and decompression programs FTP and Telnet programsFTP and Telnet programs Graphics programsGraphics programs


SummarySummary• The Internet and WWW are The Internet and WWW are simple and enjoyablesimple and enjoyable

concepts to learnconcepts to learn• TCP/IP protocolTCP/IP protocol and software transmit data (Web pages, and software transmit data (Web pages,

e-mail messages) across the Internete-mail messages) across the Internet• Computers use IP addresses and humans use URLsComputers use IP addresses and humans use URLs• DNS software provides DNS software provides URL-to-IP-addressURL-to-IP-address conversion conversion• Top-level domains: .com, .edu, .gov, .org, .net, and .milTop-level domains: .com, .edu, .gov, .org, .net, and .mil• E-mail addresses use E-mail addresses use username@DNSusername@DNS-domain-domain format format• Intranets and Extranets are Intranets and Extranets are private networksprivate networks

mastering the internet, xhtml, and javascript chapter 1 overview of the internet

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