MELJUN CORTES Internet & WWW

7/28/2019 MELJUN CORTES Internet & WWW

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The Internet and the World Wide Web

MELJUN CORTES


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Electronic Commerce, Sixth Edition 2

The Internet and the World Wide

Web Computer network

Any technology that allows people to connect

computers to each other

The Internet

A large system of interconnected computer

networks spanning the globe

World Wide Web

A subset of computers on the Internet


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Origins of the Internet

Early 1960s

U.S. Department of Defense funded research to

explore creating a worldwide network

In1969, Defense Department researchersconnected four computers into a network

called ARPANET

Throughout the 1970s and 1980s Academic researchers connected to ARPANETand contributed to its technological developments


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New Uses for the Internet

1972

E-mail was born

Mailing list

E-mail address that forwards any message

received to any user who has subscribed to the list

Usenet

Started by a group of students and programmersat Duke University and the University of North

Carolina


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Growth of the Internet

In 1991, the NSF Eased restrictions on commercial Internet activity

Began implementing plans to privatize the Internet

Network access points (NAPs) Basis of the new structure of the Internet

Network access providers Sell Internet access rights directly to larger

customers and indirectly to smaller firms andindividuals through ISPs


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Growth of the Internet


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Emergence of the World Wide Web

(continued) Tim Berners-Lee developed code for a

hypertext server program

Hypertext server Stores files written in the hypertext markup

language

Lets other computers connect to it and read files

Hypertext Markup Language (HTML)

Includes a set of codes (or tags) attached to text



Packet-Switched Networks

Local area network (LAN)

Network of computers located close together

Wide area networks (WANs)

Networks of computers connected over greater

distances



Packet-Switched Networks

(continued) Packets

Files and e-mail messages on a packet-switched

network that are broken down into small pieces Travel from computer to computer along the

interconnected networks until they reach their

destinations



Routing Packets

Routing computers

Computers that decide how best to forwardpackets

Routing algorithms

Rules contained in programs on router computersthat determine the best path on which to sendpackets

Programs apply their routing algorithms toinformation they have stored in routing tables



Router-based Architecture of the

Internet



Internet Protocols

Protocol Collection of rules for formatting, ordering, and error-

checking data sent across a network

Rules for message handling Independent networks should not require any internal

changes to be connected to the network

Packets that do not arrive at their destinations mustbe retransmitted from their source network

Router computers act as receive-and-forward devices No global control exists over the network



TCP/IP

TCP

Controls disassembly of a message or a file into

packets before transmission over the Internet

Controls reassembly of packets into their original

formats when they reach their destinations

IP

Specifies addressing details for each packet



IP Addressing

Internet Protocol version 4 (IPv4)

Uses a 32-bit number to identify computers

connected to the Internet

Base 2 (binary) number system

Used by computers to perform internal

calculations

Subnetting Use of reserved private IP addresses within LANs

and WANs to provide additional address space



IP Addressing (continued)

Private IP addresses

Series of IP numbers not permitted on packets

that travel on the Internet

Network Address Translation (NAT) device

Used in subnetting to convert private IP addresses

into normal IP addresses

Internet Protocol version 6 (IPv6) Protocol that will replace IPv4

Uses a 128-bit number for addresses



Domain Names

Sets of words assigned to specific IP

addresses

Top-level domain (or TLD) Rightmost part of a domain name

Internet Corporation for Assigned Names and

Numbers (ICANN) Responsible for managing domain names and

coordinating them with IP address registrars



Top-Level Domain Names


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Web Page Request and Delivery

Protocols Web client computers

Run software called Web client software or Web

browser software Web server computers

Run software called Web server software

Client/server architecture

Combination of client computers running Web

client software and server computers running Web

server software


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Web Page Request and Delivery

Protocols (continued)

Hypertext Transfer Protocol (HTTP)

Set of rules for delivering Web page files over the

Internet

Uniform Resource Locator (URL)

Combination of the protocol name and domain

name Allows user to locate a resource (the Web page)

on another computer (the Web server)


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Electronic Mail Protocols

Electronic mail (e-mail)

Must be formatted according to a common set of

rules

E-mail server Computer devoted to handling e-mail

E-mail client software

Used to read and send e-mail Examples include Microsoft Outlook and Netscape

Messenger


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Electronic Mail Protocols

(continued) Simple Mail Transfer Protocol (SMTP)

Specifies format of a mail message

Post Office Protocol (POP) POP message can tell the e-mail server to

Send mail to a users computer and delete it from

the e-mail server

Send mail to a users computer and not delete it Simply ask whether new mail has arrived

Provides support for Multipurpose Internet Mail

Extensions (MIME)


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Intranets and Extranets

Intranet

Interconnected network that does not extend

beyond the organization that created it

Extranet

Intranet extended to include entities outside the

boundaries of an organization

Connects companies with suppliers, business

partners, or other authorized users


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Internet Connection Options

Bandwidth

Amount of data that can travel through a

communication line per unit of time

Net bandwidth Actual speed that information travels

Symmetric connections

Provide the same bandwidth in both directions

Asymmetric connections

Provide different bandwidths for each direction


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Voice-Grade Telephone

Connections POTS, or plain old telephone service

Uses existing telephone lines and an analog

modem Provides bandwidth between 28 and 56 Kbps

Digital Subscriber Line (DSL)

Connection methods do not use a modem

Integrated Services Digital Network (ISDN)

Bandwidths between 128 Kbps and 256 Kbps


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Broadband Connections

Operate at speeds of greater than 200 Kbps

Asymmetric digital subscriber (ADSL)

Transmission bandwidth is from 100 to 640 Kbps

upstream and from 1.5 to 9 Mbps downstream

Cable modems

Provide transmission speeds between 300 Kbps and

1 Mbps

DSL

Private line with no competing traffic


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Leased-Line Connections

DS0 (digital signal zero)

Telephone line designed to carry one digital signal

T1 line (also called a DS1)

Carries 24 DS0 lines and operates at 1.544 Mbps

Fractional T1

Provides service speeds of 128 Kbps and upward in

128-Kbps increments

T3service (also called DS3)

Offers 44.736 Mbps


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Wireless Connections

Bluetooth

Designed for personal use over short distances

Low-bandwidth technology, with speeds of up to

722 Kbps

Networks are called personal area networks

(PANs) or piconets

Consumes very little power

Devices can discover each other and exchange

information automatically


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Wireless Ethernet (Wi-Fi or

802.11b) Most common wireless connection

technology for use on LANs

Wireless access point (WAP) Device that transmits network packets between

Wi-Fi-equipped computers and other devices

Has potential bandwidth of 11 Mbps and a

range of about 300 feet

Devices are capable of roaming


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Wireless Ethernet (Wi-Fi or

802.11b) (continued) 802.11a protocol

Capable of transmitting data at speeds up to 54

Mbps 802.11g protocol

Has 54 Mbps speed of 802.11a

Compatible with 802.11b devices

802.11n

Expected to offer speeds up to 320 Mbps


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Cellular Telephone Networks

Third-generation (3G) cell phones

Combine latest technologies available today

Short message service (SMS)

Protocol used to send and receive short text

messages

Mobile commerce (m-commerce)

Describes the kinds of resources people might

want to access using wireless devices


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Internet2 and the Semantic Web

Internet2

Experimental test bed for new networking

technologies

Has achieved bandwidths of 10 Gbps and more on

parts of its network

Used by universities to conduct large collaborative

research projects


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Internet2 and the Semantic Web

(continued) Semantic Web

Project by Tim Berners-Lee

If successful, it would result in words on Webpages being tagged (using XML) with theirmeanings

Resource description framework (RDF)

Set of standards for XML syntax

Ontology Set of standards that defines relationships among

RDF standards and specific XML tags

MELJUN CORTES Internet & WWW

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