internet technologies. e-commerce: the second wave, fifth annual edition2 the internet and the world...

Internet technologies

E-Commerce: The Second Wave, Fifth Annual Edition 2

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


Growth of the Internet


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


LAN (Local Area Network)


MAN (Metropolitan Area Network)


WAN (Wide Area Network)


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


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


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


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

internet technologies. e-commerce: the second wave, fifth annual edition2 the internet and the world...

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