E-commerce (Technology Infrastructure ;the internet and world wide web)

2. 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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3. 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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4. 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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5. 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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6. 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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7. 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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8. Growth of the Internet
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9. 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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10. 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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11. 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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12. 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 the
interconnected networks until they reach their
destinations
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13. 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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14. Router-based Architecture of the Internet
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15. 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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16. 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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17. 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
Sub netting
Use of reserved private IP addresses within LANs
and WANs to provide additional address space
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18. 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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19. 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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20. Top-level Domain Names
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21. 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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22. 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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23. 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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24. 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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25. 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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26. Development of Markup Languages
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27. 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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28. 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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29. 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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30. 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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31. Processing a Request for an XML Page
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32. 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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33. 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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34. 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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35. 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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36. 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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37. 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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38. 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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39. 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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40. 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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41. 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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42. 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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43. 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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44. 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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45. 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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46. 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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47. 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
E-Commerce: The Second Wave, Fifth Annual Edition 47