Chapter 2:Technology Infrastructure: The Internet and the World

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Oct 24, 2013 (3 years and 9 months ago)

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E
-
Commerce: The Second Wave

Fifth Annual Edition




Chapter 2:

Technology Infrastructure:
The Internet and the World
Wide Web

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Commerce: The Second Wave, Fifth Annual Edition

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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 1980s


Academic researchers connected to
ARPANET and contributed to its technological
developments

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New Uses for the Internet


1972


E
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mail was born


Mailing list


E
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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 Internet
activity


Began implementing plans to privatize the
Internet


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 and
individuals 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
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Switched Networks (Continued)


Circuit switching


Centrally controlled, single
-
connection model


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


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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, and
error
-
checking data sent across a network


Rules contributing to success of Internet


Independent networks should not require any
internal changes to be connected to the network


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


Router computers act as receive
-
and
-
forward
devices


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
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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
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mail server


Computer devoted to handling e
-
mail


E
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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 user’s computer and delete it from
e
-
mail server


Send mail to user’s 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 network


A 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 their
protocols


IP tunneling


Effectively creates a private passageway
through the public Internet


Encapsulation


Process used by VPN software


VPN software


Must be installed on the computers at both
ends 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 bandwidth


Actual 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


T3

service (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
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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Fixed
-
Point Wireless


One version

uses 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 being
tagged (using XML) with their meanings


Resource description framework (RDF)


Set of standards for XML syntax


Ontology


Set of standards that defines relationships
among 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