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MELJUN CORTES Internet MELJUN CORTES Internet Presentation Transcript

  • The Internet and the World Wide WebMELJUN CORTES
  • 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
  • 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
  • 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
  • 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
  • Growth of the InternetElectronic Commerce, Sixth Edition 6
  • 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
  • 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
  • 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
  • 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
  • Router-based Architecture of the InternetElectronic Commerce, Sixth Edition 11
  • 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
  • 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
  • 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
  • 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
  • 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
  • Top-Level Domain NamesElectronic Commerce, Sixth Edition 17
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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