meljun cortes e commerce chapter2

Chapter 2:Technology Infrastructure: The Internet

and the World Wide Web

Electronic Commerce, Sixth 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 (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


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 a network called ARPANET

• Throughout the 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 a group of students and programmers

at Duke University and the University of North Carolina


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 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 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


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 packets

– 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 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 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 the 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 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


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 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


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

• Send mail to a 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 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


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 are interpreted by a Web browser and are used by it to format the display of the text

• HTML links

– Linear hyperlink structures

– Hierarchical hyperlink structures


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 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


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


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


VPN Architecture Example


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


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


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 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

• 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 a 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 a system of repeaters to forward 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


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, it 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 (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

meljun cortes e commerce chapter2

Documents

internet protocols

internetelectronic commerce

internet access rights

ispselectronic commerce

hypertextelectronic

xmlelectronic commerce

otherelectronic commerce

commercial internet