technology infrastructure and the world wide web

7/28/2019 Technology Infrastructure and the world wide web

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E-Commerce

Chapter 2:Technology Infrastructure:

The Internet and the WorldWide Web


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Objectives

In this chapter, you will learn about:

The origin, growth, and current structure of

the Internet

How packet-switched networks are combined

to form the Internet

How Internet protocols and Internet

addressing work

The history and use of markup languages on

the Web, including SGML, HTML, and XML


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Objectives

How HTML tags and links work on the World

Wide Web

The differences among internets, intranets,and extranets

Options for connecting to the Internet,

including cost and bandwidth factors

About Internet2 and the Semantic Web


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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 researchers

Connected four computers into network called

ARPANET

Throughout 1970s and 1980sAcademic researchers connected to

ARPANET and 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 group of students and

programmers at Duke University and the

University of North Carolina


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Growth of the Internet

In 1991, NSF

Eased restrictions on commercial Internetactivity

Began implementing plans to privatize theInternet

Network access points (NAPs)

Basis of new structure 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

The Web

Software that runs on computers connected to

the Internet

Vannevar Bush

Speculated that engineers would eventually

build a memory extension device (the Memex)

In the 1960s

Ted Nelson described a similar system called

hypertext


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Emergence of the World Wide Web

(Continued) Tim Berners-Lee

Developed code for hypertext server program

Hypertext server Stores files written in hypertext markup

language

Lets other computers connect to it and read

files Hypertext Markup Language (HTML)

Includes set of codes (or tags) attached to text


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Packet-Switched Networks

Local area network (LAN)

Network of computers located close together

Wide area networks (WANs)

Networks of computers connected over

greater distances

Circuit

Combination of telephone lines and closed

switches that connect them to each other


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Packet-Switched Networks (Continued)

Circuit switching

Centrally controlled, single-connection model

Packets Files and e-mail messages on apacket-

switchednetwork that are broken down into

small pieces

Travel from computer to computer along the

interconnected networks until they reach their

destinations


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Routing Packets

Routing computers

Computers that decide how best to forward

packets

Routing algorithms

Rules contained in programs on router

computers that determine the best path on

which to send packet

Programs apply their routing algorithms to

information they have stored in routing tables


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Router-based Architecture of the

Internet


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Internet Protocols

Protocol

Collection of rules for formatting, ordering, anderror-checking data sent across a network

Rules contributing to success of Internet

Independent networks should not require anyinternal changes to be connected to the network

Packets that do not arrive at their destinationsmust be retransmitted from their source network

Router computers act as receive-and-forwarddevices

No global control exists over the network


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TCP/IP

TCP

Controls disassembly of a message or a file

into packets before transmission over Internet Controls reassembly of packets into their

original formats when they reach their

destinations

IP

Specifies addressing details for each packet


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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


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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


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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


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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 computer

Runs 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 also be formatted according to common

set of rules

E-mail server

Computer devoted to handling e-mail

E-mail client software

Used to read and send e-mail Example: Microsoft Outlook, 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 users computer and delete it from

e-mail server

Send mail to 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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Markup Languages and the Web

Text markup language

Specifies set of tags that are inserted into text

Standard Generalized Markup Language

(SGML)

Older and complex text markup language

A meta language

World Wide Web Consortium (W3C)

Not-for-profit group that maintains standards

for the Web


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Development of Markup Languages


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Standard Generalized Markup

Language Offers a system of marking up documents

that is independent of any software

application

Nonproprietary and platform independent

Offers user-defined tags

Costly to set up and maintain


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Hypertext Markup Language (HTML)

Prevalent markup language used to create

documents on the Web today

HTML tags Interpreted by Web browser and used by it to

format the display of the text

HTML Links Linear hyperlink structure

Hierarchical hyperlink structure


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Hypertext Markup Language (HTML)

(Continued) Scripting languages and style sheets

Most common scripting languages

JavaScript, JScript, Perl, and VBScript Cascading Style Sheets (CSS)

Sets of instructions that give Web developers

more control over the format of displayed

pages Style sheet

Usually stored in a separate file

Referenced using the HTML style tag


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Extensible Markup Language (XML)

Uses paired start and stop tags

Includes data management capabilities that

HTML cannot provide Differences between XML and HTML

XML is not a markup language with defined

tags

XML tags do not specify how text appears on

a Web page


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Processing a Request for an XML Page


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Intranets and Extranets

Intranet

Interconnected network that does not extend

beyond organization that created it

Extranet

Intranet extended to include entities outside

boundaries of organization

Connects companies with suppliers, business

partners, or other authorized users


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Public and Private Networks

Public network

Any computer network or telecommunications

network available to the public

Private networkA private, leased-line connection between two

companies that physically connects their

intranets

Leased line

A permanent telephone connection between

two points


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Virtual Private Network (VPN)

Extranet that uses public networks and theirprotocols

IP tunneling

Effectively creates a private passagewaythrough the public Internet

Encapsulation

Process used by VPN software

VPN software

Must be installed on the computers at bothends of the transmission


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Internet Connection Options

Bandwidth

Amount of data that can travel through a

communication line per unit of time

Net bandwidthActual speed that information travels

Symmetric connections

Provide 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 analog

modem

Provide bandwidth between 28 and 56 Kbps

Digital Subscriber Line (DSL)

Connection methods do not use modem

Integrated Services Digital Network (ISDN)

Offers 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 1 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 upto 722 Kbps

Networks are calledpersonal area networks

(PANs) orpiconets

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 andrange 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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Fixed-Point Wireless

One versionuses system of repeaters to

forward radio signal from ISP to customers

Repeaters Transmitter-receiver devices (transceivers)

Mesh Routing

Directly transmits Wi-Fi packets through

hundreds, or even thousands, of short-range

transceivers


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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

Would result in words on Web pages beingtagged (using XML) with their meanings

Resource description framework (RDF)

Set of standards for XML syntax

Ontology

Set of standards that defines relationshipsamong RDF standards and specific XML tags


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Summary

TCP/IP

Protocol suite used to create and transport

information packets across the Internet

POP, SMTP, and IMAP

Protocols that help manage e-mail

Languages derived from SGML Hypertext Markup Language (HTML)

Extensible Markup Language (XML)


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Summary

Intranets

Private internal networks

Extranet

Used when companies want to collaborate

with suppliers, partners, or customers

Internet2

Experimental network built by a consortium of

research universities and businesses

technology infrastructure and the world wide web

Documents