Technology infrastructure the internet and the world wide web
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Technology Infrastructure: The Internet and the World Wide Web. Electronic Commerce . 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

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Technology Infrastructure: The Internet and the World Wide Web

Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


Origins of the Internet

  • Early 1960s

    • U.S. Department of Defense funded research to explore creating a worldwide network

  • In 1969

    • 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

Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


Packet-Switched Networks (continued)

  • Circuit switching

    • Centrally controlled, single-connection model

  • Packets

    • Files and e-mail messages on a packet-switched network are broken down into small pieces, called packets

    • Travel from computer to computer along the interconnected networks until they reach their destinations

Electronic Commerce


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

Electronic Commerce


Electronic Commerce


Internet Protocols

  • Protocol

    • Collection of rules for formatting, ordering, and error-checking data sent across a network

  • Rules for message handling include:

    • 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

Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


Domain Names

  • A domain name is a set of words assigned to a specific IP address

  • 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

Electronic Commerce


Electronic Commerce


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

Electronic Commerce


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 a user to locate a resource (the Web page) on another computer (the Web server)

Electronic Commerce


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 Commerce


Electronic Mail Protocols (continued)

  • Simple Mail Transfer Protocol (SMTP)

    • Specifies the format of a mail message

  • Post Office Protocol (POP)

    • POP messages 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

    • POP provides support for Multipurpose Internet Mail Extensions (MIME)

Electronic Commerce


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 more complex text markup language than HTML

    • A meta language

  • World Wide Web Consortium (W3C)

    • Not-for-profit group that maintains standards for the Web

Electronic Commerce


Electronic Commerce


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

Electronic Commerce


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 can be structured as:

    • Linear hyperlink structures

    • Hierarchical hyperlink structures

Electronic Commerce


Hypertext Markup Language (HTML) (continued)

  • The most common scripting languages include JavaScript, JScript, Perl, and VBScript

  • Cascading Style Sheets (CSS) are sets of instructions that give Web developers more control over the format of displayed pages

    • Style sheet is:

      • Usually stored in a separate file

      • Referenced using the HTML style tag

Electronic Commerce


Extensible Markup Language (XML)

  • XML uses paired start and stop tags

  • It 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

Electronic Commerce


Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


Virtual Private Network (VPN)

  • VPN

    • An 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

Electronic Commerce


Electronic Commerce


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

Electronic Commerce


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 that do not use a modem

  • Integrated Services Digital Network (ISDN)

    • Bandwidths between 128 Kbps and 256 Kbps

Electronic Commerce


Broadband Connections

  • Broadband connections operate at speeds of greater than 200 Kbps

  • Asymmetric digital subscriber line (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

Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


Wireless Ethernet (Wi-Fi)

  • Wireless Ethernet (Wi-Fi or 802.11b) is the 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 a potential bandwidth of 11 Mbps and a range of about 300 feet

  • Devices are capable of roaming

Electronic Commerce


Wireless Ethernet (Wi-Fi) (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

Electronic Commerce


Fixed-Point Wireless

  • One versionof fixed-point wirelessuses 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

Electronic Commerce


Cellular Telephone Networks

  • Third-generation (3G) cell phones

    • Combine the 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

Electronic Commerce


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

Electronic Commerce


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

Electronic Commerce


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)

Electronic Commerce


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

Electronic Commerce


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