Session 2

Slide 1: AGENDA: StarHub case debrief Infrastructure for e-commerce In-class exercise: Blog analysis HTML lab Session 2: Technology Infrastructure: The Internet and the Web

Slide 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 E-Commerce Infrastructure 2

Slide 3: 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 E-Commerce Infrastructure 3

Slide 4: 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 E-Commerce Infrastructure 4

Slide 5: 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 E-Commerce Infrastructure 5

Slide 6: New Uses for the Internet • 1972 • E-mail born • Mailing list (listserve) • E-mail address that forwards all messages received to any user who subscribed to the list Usenet • • Started by group of students and programmers at Duke University and University of North Carolina • External returns to use E-Commerce Infrastructure 6

Slide 7: 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 E-Commerce Infrastructure 7

Slide 8: Growth of the Internet E-Commerce Infrastructure 8

Slide 9: 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 E-Commerce Infrastructure 9

Slide 10: 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 • Browser displays text and images on client (1994) E-Commerce Infrastructure 10

Slide 11: 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 E-Commerce Infrastructure 11

Slide 12: 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 E-Commerce Infrastructure 12

Slide 13: 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 E-Commerce Infrastructure 13

Slide 14: Router-based Architecture of the Internet E-Commerce Infrastructure 14

Slide 15: 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 E-Commerce Infrastructure 15

Slide 16: 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 E-Commerce Infrastructure 16

Slide 17: The Heart of the Internet? “It’s the TCP/IP Protocol Stack” Applications Web • Applications Email • Video/Audio • TCP/IP Middleware Services Access Technologies Ethernet (LAN) • “Choke Wireless (LMDS, WiFi, • TCP/IP Point” Cellular) Network Cable • Technology DSL • Substrate Satellite • Access Technologies E-Commerce Infrastructure 17

Slide 18: 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 V6 extends addressing, control functionality E-Commerce Infrastructure 18

Slide 19: 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 E-Commerce Infrastructure 19

Slide 20: 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 E-Commerce Infrastructure 20

Slide 21: Top-level Domain Names E-Commerce Infrastructure 21

Slide 22: 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 E-Commerce Infrastructure 22

Slide 23: 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) E-Commerce Infrastructure 23

Slide 24: 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 E-Commerce Infrastructure 24

Slide 25: 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) E-Commerce Infrastructure 25

Slide 26: 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 E-Commerce Infrastructure 26

Slide 27: 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 E-Commerce Infrastructure 27

Slide 28: 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 E-Commerce Infrastructure 28

Slide 29: 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 E-Commerce Infrastructure 29

Slide 30: 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 E-Commerce Infrastructure 30

Slide 31: 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 E-Commerce Infrastructure 31

Slide 32: 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 E-Commerce Infrastructure 32

Slide 33: 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 E-Commerce Infrastructure 33

Slide 34: Wireless Ethernet (Wi-Fi or 802.11b/g/n) • 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 11-54 Mbps and range of about 300 feet (n >100 Mbps) • Devices capable of roaming E-Commerce Infrastructure 34

Slide 35: Wireless Ethernet (Wi-Fi or 802.11a/b/g/n) • 802.11a protocol • Capable of transmitting data at speeds up to 54 Mbps, on different frequencies to 802.11b • 802.11g protocol • Has 54 Mbps speed of 802.11a • Compatible with 802.11b devices • 802.11n emerging standard • Expected to offer speeds up to 320 Mbps E-Commerce Infrastructure 35

Slide 36: 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 acting as routers E-Commerce Infrastructure 36

Slide 37: 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 E-Commerce Infrastructure 37

Slide 38: 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 E-Commerce Infrastructure 38

Slide 39: 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 E-Commerce Infrastructure 39

Slide 40: 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 E-Commerce Infrastructure 40

Slide 41: Development of Markup Languages E-Commerce Infrastructure 41

Slide 42: 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 E-Commerce Infrastructure 42

Slide 43: 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 E-Commerce Infrastructure 43

Slide 44: 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 E-Commerce Infrastructure 44

Slide 45: 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 E-Commerce Infrastructure 45

Slide 46: Processing a Request for an XML Page E-Commerce Infrastructure 46

Slide 47: 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) E-Commerce Infrastructure 47

Slide 48: 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 Infrastructure 48