technology infrastructure and the world wide web
TRANSCRIPT
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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