Chapter02

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Chapter02

  1. 1. Advanced Diploma of Information Technology MIT Nguyễn Hữu Phát Kent International College 80 hours
  2. 2. 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: The Second Wave, Fifth Annual Edition 3
  3. 3.  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: The Second Wave, Fifth Annual Edition 4
  4. 4.  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: The Second Wave, Fifth Annual Edition 5
  5. 5.  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: The Second Wave, Fifth Annual Edition 6
  6. 6.  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 group of students and programmers at Duke University and the University of North Carolina E-Commerce: The Second Wave, Fifth Annual Edition 7
  7. 7.  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: The Second Wave, Fifth Annual Edition 8
  8. 8. http://www.internetworldstats.com
  9. 9. E-Commerce: The Second Wave, Fifth Annual Edition 10
  10. 10. The $23.4 billion in annual internet advertising spending exceeded advertising on cable TV for the first time (which was $21.4 billion), and took the No. 3 spot behind national and local TV ads ($29.8 billion) and newspaper ads ($34.4 billion).
  11. 11. Internet advertising is almost twice as large as broadcast TV advertising was in its 14th year ($13.3 billion) and nearly four times as large as cable TV ($6.5 billion).
  12. 12.  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
  13. 13.  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
  14. 14.  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
  15. 15.  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
  16. 16.  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
  17. 17. E-Commerce: The Second Wave, Fifth Annual Edition 18
  18. 18.  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
  19. 19.  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: The Second Wave, Fifth Annual Edition 20
  20. 20.  Internet Protocol version 4/6 (IPv4/6) › 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 E-Commerce: The Second Wave, Fifth Annual Edition 21
  21. 21.  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
  22. 22.  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
  23. 23. E-Commerce: The Second Wave, Fifth Annual Edition 24
  24. 24.  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
  25. 25.  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)
  26. 26.  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
  27. 27.  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)
  28. 28.  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
  29. 29.  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
  30. 30.  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: The Second Wave, Fifth Annual Edition 35
  31. 31.  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: The Second Wave, Fifth Annual Edition 36
  32. 32.  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: The Second Wave, Fifth Annual Edition 37
  33. 33. E-Commerce: The Second Wave, Fifth Annual Edition 38
  34. 34.  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
  35. 35.  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
  36. 36.  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
  37. 37.  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
  38. 38.  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
  39. 39.  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: The Second Wave, Fifth Annual Edition 44
  40. 40.  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
  41. 41.  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
  42. 42.  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 E-Commerce: The Second Wave, Fifth Annual Edition 47
  43. 43.  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 E-Commerce: The Second Wave, Fifth Annual Edition 48
  44. 44.  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
  45. 45.  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
  46. 46.  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: The Second Wave, Fifth Annual Edition 51
  47. 47.  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
  48. 48.  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: The Second Wave, Fifth Annual Edition 53
  49. 49.  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: The Second Wave, Fifth Annual Edition 54

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