e-commerce: the second wave fifth annual edition chapter 2: technology infrastructure: the internet...

E-Commerce: The Second WaveFifth Annual Edition

Chapter 2:Technology Infrastructure: The Internet and the World

Wide Web

E-Commerce: The Second Wave, Fifth Annual Edition 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


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


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


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


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


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


Growth of the Internet


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


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


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


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


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


Router-based Architecture of the Internet


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


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


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


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


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


Top-level Domain Names


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


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)


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


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)


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


Development of Markup Languages


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


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


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


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


Processing a Request for an XML Page


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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)


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 chapter 2: technology infrastructure: the internet...

Documents

internet slide

internet protocols

world wide web slide

hypertext slide

internet access rights

semantic web slide

commercial internet

internet vannevar bush