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Lecture 03 Going Online

Lecture 03 Going Online

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Lecture 03 Going Online

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  1. Lecture 03 Going Online Topics Basics Connecting to the Internet World Wide Web Internet Applications Internet Ethics © 2005 Prentice-Hall, Inc. Slide 1

  2. Basics Internet: worldwide collection of interconnected networks; Computers are no longer lonely ARPANET (1969): network for scientists that evolved into the Internet Internet backbone: major communications lines and nodes to which thousands of hosts are connected © 2005 Prentice-Hall, Inc. Slide 2

  3. Basics No one group controls the Internet, but some organizations coordinate Internet activities The Internet Society to assure the open development, evolution, and use of the Internet ICANN (Internet Corporation for Assigned Names and Numbers): responsible for coordinating the assignment and allocation of domain names and internet addresses W3C (World Wide Web Consortium): create and maintain technical specification to keep pace with changing technologies used on the Internet © 2005 Prentice-Hall, Inc. Slide 3

  4. Connecting to the Internet Bandwidth: amount of information that can be sent over the channel, in bps (bits per second) Broadband – high bandwidth Narrowband – low bandwidth © 2005 Prentice-Hall, Inc. Slide 5

  5. Connecting to the Internet Narrowband Dialup service Phone line Modem 56 Kbps © 2005 Prentice-Hall, Inc. Slide 8

  6. Connecting to the Internet Broadband Cable TV cable LAN PC card Cable modem 1 M~10 Mbps DSL (Digital Subscriber Line) Phone line LAN PC card ADSL modem Upstream rate: 128Kbps~1.5Mbps Downstream rate: 1.5M~9Mbps © 2005 Prentice-Hall, Inc. Slide 9

  7. Connecting to the Internet Broadband (cont) Satellite Satellite disc Satellite modem LAN PC card Upstream rate:56Kbps~1.5Mbps Downstream rate: 400Kbps~1.5Mbps Latency – time lag in communication Wireless AP (Access Points) Wireless LAN PC card Wi-Fi (Wireless Fidelity) standard Wireless-B (IEEE 802.11b)/11Mbps/300ft Wireless-A (IEEE 802.11b)/54Mbps/50ft Wireless-G (IEEE 802.11g)/54Mbps/Far better than A © 2005 Prentice-Hall, Inc. Slide 9

  8. Connecting to the Internet ISP (Internet service provider) Communication software (Dialup/ DSL) Hinet/ Seednet Information service gateway Communication software (link to the information network of AOL) user ID and password AOL (America OnLine)/ MSN Direct LAN connection T-1 line (1.544Mbps) T-3 line (44.736Mbps) © 2005 Prentice-Hall, Inc. Slide 10

  9. Connecting to the Internet Protocol TCP/IP (Transmission Control Protocol/Internet Protocol) Protocol: set of rules for how computers communicate, defining message format and interaction patterns Packet: the part of a message that contains the data and the address the message is being sent to Packet switching TCP dividing files into packets IP routing each packet to destination © 2005 Prentice-Hall, Inc. Slide 11

  10. Connecting to the Internet IP (Internet Protocol) address Identify each device attached to the Internet by numbers Four numbers, each 0~255, separated by periods, e.g., Fixed vs. Dynamic IP address Domain names Identify each device attached to the Internet by symbols, e.g., top-level domains: denote affiliation .com/.edu DNS (Domain name system) Translate domain names to IP addresses © 2005 Prentice-Hall, Inc. Slide 12

  11. Connecting to the Internet URL (Uniform Resource Locator) Identify each resource on the Internet, e.g., Four parts access method: ftp Domain name: Path name: www/InfoTech Resouce: Lecture01.ppt © 2005 Prentice-Hall, Inc. Slide 12

  12. Connecting to the Internet Client program runs on user’s computer Internet browser/ FTPPro Server program – runs on server computer © 2005 Prentice-Hall, Inc. Slide 14

  13. Connecting to the Internet More devices to connect to the Internet televisions/ Freezer video game consoles PDA/ cellular phones Internet appliances A specific device to go online at anytime, any place © 2005 Prentice-Hall, Inc. Slide 13

  14. World Wide Web WWW, the Web (World Wide Web) Website Web servers Containing webpages and server programs Home page – first page you see at a site Webpage A document containing multimedia data and hyperlinks Hyperlinks – allow user to click on an icon and be taken to other resources on the Internet Document structure is specified by HTML/ XML/… © 2005 Prentice-Hall, Inc. Slide 17

  15. World Wide Web WWW, the Web (World Wide Web) Browsers A client program which interprets a webpage and interacts with the Web server IE/ Netscape/ KKman/ Mozilla Firefox HTTP (Hypertext Transfer Protocol) A protocol for client and server programs to communicate © 2005 Prentice-Hall, Inc. Slide 17

  16. World Wide Web HTML (HyperText Markup Language) A language to format a webpage using paired tags,e.g., <i> </i>; <a> </a> Define howeach multimedia component in a webpage is displayed XML (eXtensible Markup Language) A meta-language to define the language for formatting a webpage © 2005 Prentice-Hall, Inc. Slide 12

  17. World Wide Web Browser Plug-ins Software modules that are integrated into a browser to add flexibility Animation/ multimedia displays Applets or ActiveX controls Streaming audio and video Media is presented continuously instead of being downloaded Java RTE/ Flash player/ Window Media Player/ RealJukebox/ QuickTime/iPIX Movies/ Acrobat Reader/ Liquid Player © 2005 Prentice-Hall, Inc. Slide 18

  18. World Wide Web Common operations of Browser Back: go to previous page Forward: go to next page Stop: ends transmission Refresh: reload Web page Bookmarks (Favorites): have browser remember favorite sites Location bar: where user enters URL © 2005 Prentice-Hall, Inc. Slide 21

  19. World Wide Web Finding information on the Web Browsing: just looking around portals Portal: a site that provides a number of services Classified Index database Yahoo/ Yam/ Excite.. Searching: trying to find specific information by using search engines Search Engine: a program that goes to the Internet or within a Website to search for webpages users need Google/ Yahoo/ Excite/ MSN/Hotbot/ Ask Jeeves/ Infoseek/ AltaVista/ Metacrawler/ © 2005 Prentice-Hall, Inc. Slide 26

  20. World Wide Web Tips for searching the Net Read the rules for each search engine Try multiple search engines Follow hyperlinks Choose search terms carefully Be persistent Use FAQ (Frequently Asked Questions) lists answers to questions asked often at a particular site © 2005 Prentice-Hall, Inc. Slide 29

  21. Internet Applications Resource retrieval WWW Web server user-friendly multimedia documents hyperlinks interactive frames Integration of Internet applications, e.g., FTP, email, .. © 2005 Prentice-Hall, Inc. Slide 32

  22. Internet Applications Resource retrieval (cont) FTP (File Transfer Protocol) FTP server Easily download/upload files Anonymous FTP sites Jukebox Help a client program to gather mp3 and other audio files from Internet music resources © 2005 Prentice-Hall, Inc. Slide 33

  23. Internet Applications Communication E-mail e-mail server file attachments Newsgroups Mailing lists or listservs push technology – information is delivered automatically from the server to client programs Chat Instant messaging (Whiteboarding) © 2005 Prentice-Hall, Inc. Slide 34

  24. Internet Ethics Netiquette Using all capital letters is considered SHOUTING Never send unsolicited e-mail (spam) Consider your audience when forwarding Internet content © 2005 Prentice-Hall, Inc. Slide 36

  25. Internet Ethics Netiquette (cont) Never reveal others’ personal information Be patient with people who are justgetting online (newbies) Don’t comment on others’ spelling,grammar, or punctuation © 2005 Prentice-Hall, Inc. Slide 37

  26. Internet Ethics Netiquette (cont) Keep private communications private Consider e-mail attachment sizebefore sending to someone (using dialup) Confirm virus warnings before forwarding Use an anti-virus program © 2005 Prentice-Hall, Inc. Slide 38

  27. Internet Ethics Shady side of the Internet Hackers and crackers Hate mongers Pornography Filtering programs Spam Gambling © 2005 Prentice-Hall, Inc. Slide 40