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  1. 1. The Internet and the World Wide WebMELJUN CORTES
  2. 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 InternetElectronic Commerce, Sixth Edition 2
  3. 3. 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 developmentsElectronic Commerce, Sixth Edition 3
  4. 4. 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 CarolinaElectronic Commerce, Sixth Edition 4
  5. 5. 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 ISPsElectronic Commerce, Sixth Edition 5
  6. 6. Growth of the InternetElectronic Commerce, Sixth Edition 6
  7. 7. 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 textElectronic Commerce, Sixth Edition 7
  8. 8. Packet-Switched Networks• Local area network (LAN) – Network of computers located close together• Wide area networks (WANs) – Networks of computers connected over greater distancesElectronic Commerce, Sixth Edition 8
  9. 9. Packet-Switched Networks (continued)• 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 destinationsElectronic Commerce, Sixth Edition 9
  10. 10. 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 tablesElectronic Commerce, Sixth Edition 10
  11. 11. Router-based Architecture of the InternetElectronic Commerce, Sixth Edition 11
  12. 12. 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 Electronic Commerce, Sixth Edition 12
  13. 13. 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 packetElectronic Commerce, Sixth Edition 13
  14. 14. 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 spaceElectronic Commerce, Sixth Edition 14
  15. 15. 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 addressesElectronic Commerce, Sixth Edition 15
  16. 16. 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 registrarsElectronic Commerce, Sixth Edition 16
  17. 17. Top-Level Domain NamesElectronic Commerce, Sixth Edition 17
  18. 18. 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 softwareElectronic Commerce, Sixth Edition 18
  19. 19. 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 Commerce, Sixth Edition 19
  20. 20. 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 MessengerElectronic Commerce, Sixth Edition 20
  21. 21. 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)Electronic Commerce, Sixth Edition 21
  22. 22. 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 usersElectronic Commerce, Sixth Edition 22
  23. 23. 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 pointsElectronic Commerce, Sixth Edition 23
  24. 24. 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 directionElectronic Commerce, Sixth Edition 24
  25. 25. 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 KbpsElectronic Commerce, Sixth Edition 25
  26. 26. 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 Electronic Commerce, Sixth Edition 26
  27. 27. 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 Electronic Commerce, Sixth Edition 27
  28. 28. 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 automaticallyElectronic Commerce, Sixth Edition 28
  29. 29. 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 roamingElectronic Commerce, Sixth Edition 29
  30. 30. 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 MbpsElectronic Commerce, Sixth Edition 30
  31. 31. 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 devicesElectronic Commerce, Sixth Edition 31
  32. 32. 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 projectsElectronic Commerce, Sixth Edition 32
  33. 33. 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 tagsElectronic Commerce, Sixth Edition 33