meljun cortes e commerce chapter 2
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Chapter 2:Technology Infrastructure: The Internet
and the World Wide Web
MELJUNCORTES
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Electronic Commerce, Sixth Edition 3
Objectives (continued)
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
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 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 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 similarsystem called hypertext
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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
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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 a packet-switched
network that are broken down into small pieces
Travel from computer to computer along theinterconnected networks until they reach their
destinations
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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
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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 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
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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
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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 LANsand 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 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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Markup Languages and the Web
Text markup language
Specifies a 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 MarkupLanguages
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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 are interpreted by a Web browserand are used by it to format the display of the
text
HTML links Linear hyperlink structures
Hierarchical hyperlink structures
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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 XMLPage
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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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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 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 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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VPN Architecture Example
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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 exchangeinformation 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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Fixed-Point Wireless
One versionuses a system of repeaters toforward a radio signal from an 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, 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
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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 (continued)
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
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