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B.A. (Mahayana Studies) 000-209 Introduction to Computer Science November 2005 - March 2006 8. The Internet

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B.A. (Mahayana Studies) 000-209 Introduction to Computer Science November 2005 - March 2006 8. The Internet A close look at the Internet and the Web, and a mention of other Internet services. Overview 1. The Internet 2. A Brief Internet History 3. TCP/IP 4. Connecting to the Internet

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  1. B.A. (Mahayana Studies)000-209 Introduction to Computer ScienceNovember 2005 - March 20068. The Internet A close look at the Internet and the Web, and a mention of other Internet services.

  2. Overview • 1. The Internet • 2. A Brief Internet History • 3. TCP/IP • 4. Connecting to the Internet • 5. The Web • 6. Web Browsers continued 000-209 Intro to CS. 8/Internet

  3. 7. Web Search Engines • 8. Web Portals • 9. Blogs and Blogging • 10. Web Page Content • 11. Writing a Web Page • 12. Other Internet Services 000-209 Intro to CS. 8/Internet

  4. 1. The Internet • The Internet is a collection of local, regional, national, and international computer networks, linked together to exchange data and distribute processing tasks. 000-209 Intro to CS. 8/Internet

  5. Internet Map 2005 000-209 Intro to CS. 8/Internet

  6. The Size of the Internet 000-209 Intro to CS. 8/Internet

  7. 2. A Brief Internet History • The Internet has been around for over 30 years. • 1958: the US created ARPA (the Advanced Research Projects Agency). • to help scientists communicate and share computer resources • triggered in part by the Soviet Union’s launch of Sputnik in 1957, the first artificial satellite continued 000-209 Intro to CS. 8/Internet

  8. The ARPANET, created in 1969, connected computers at four universities • 1971: 15 nodes: • UCLA, SRI, UCSB, Univ of Utah, BBN, MIT, RAND, SDC, Harvard, Lincoln Lab, Stanford, UIU(C), CWRU, CMU, NASA/Ames. continued 000-209 Intro to CS. 8/Internet

  9. 1982: TCP/IP • standard network communications protocol • DoD declares TCP/IP suite to be standard for DoD • 1984: DNS introduced • translates domain names into IP addresses • example domain name: fivedots.coe.psu.ac.th continued 000-209 Intro to CS. 8/Internet

  10. 1985: Symbolics.com is assigned the first registered domain (March). • Other firsts: cmu.edu, purdue.edu, rice.edu, ucla.edu (April); css.gov (June); mitre.org, .uk (July) • 1988: 2 November: the Internet worm travels through the Internet, affecting ~6,000 of the 60,000 machines continued 000-209 Intro to CS. 8/Internet

  11. 1991: World-Wide Web (WWW or Web) released by Tim Berners-Lee at CERN • CERN: the European Laboratory for Particle Physics in Geneva, Switzerland • 1995: the Web becomes the Internet service with the largest amount of traffic. continued 000-209 Intro to CS. 8/Internet

  12. 2000: Abilene backbone network deploys IPv6 (16 May) • 2002: A distributed denial of service (DDoS) attack strikes the 13 main DNS servers, knocking out 8 of them (21-23 Oct). continued 000-209 Intro to CS. 8/Internet

  13. 2004: CERNET2, the first backbone IPv6 network in China, is launched by the China Education and Research Network (CERN) • it connects 25 universities in 20 cities at speeds of 1-10Gbps (27 Dec) continued 000-209 Intro to CS. 8/Internet

  14. Sources of internet history: • http://en.wikipedia.org/wiki/History_of_the_Internet • http://www.zakon.org/robert/internet/timeline/ • http://www.computerhistory.org/exhibits/internet_history/ 000-209 Intro to CS. 8/Internet

  15. 3. TCP/IP • TCP/IP(Transport Control Protocol/Internet Protocol) • a suite of protocols that defines the internet • TCP/IP software is available for every major kind of computer operating system. • FTP, HTTP, UDP, SNMP, telnet protocols, and many others run on top of TCP/IP. continued 000-209 Intro to CS. 8/Internet

  16. FTP: file transfer over the Internet • HTTP: Web page transfer • UDP: a simple, fast communications protocol, used to implement higher-level streaming media protocols • SNMP: network management • telnet: used to login to remote machines 000-209 Intro to CS. 8/Internet

  17. Internet Addresses • Every computer that connects to the Internet is assigned a unique integer called anIP address. • a 32 bit integer, represented by a set of four numbers between 0 and 255, separated by periods • e.g. 172.30.0.5 • A router examines the IP address and then forwards a message to its destination. continued 000-209 Intro to CS. 8/Internet

  18. Most host computers have an easier-to-remember domain name. • typed in lowercase • ends with a two or three letter extension which is its top-leveldomain • e.g. takasila.coe.psu.ac.th(th is for thailand, ac is for academic) 000-209 Intro to CS. 8/Internet

  19. Some Top-level Domains 000-209 Intro to CS. 8/Internet

  20. Colour-coded Internet Map The Opte Project http://opte.prolexic.com/ January 2005 000-209 Intro to CS. 8/Internet

  21. IPv6 • The next generation IP protocol. • IPv6 features: • supports many more addresses ( 3.4 x 1038) • quality of service (QoS) parameters for real-time audio and video • better data security • packets (messages) are smaller 000-209 Intro to CS. 8/Internet

  22. DDoS • DDoS: a distributed denial-of-service attack • Many systems attack a single server • these systems may be zombies • The flood of messages forces the server to shut down • this stops real users from using the server 000-209 Intro to CS. 8/Internet

  23. 4. Connecting to the Internet • An Internet Service Provider (ISP) connects you to the Internet by providing you with a user account on a host computer that has access to the Internet. continued 000-209 Intro to CS. 8/Internet

  24. Dial-up Connections • Most people use a telephone line to access the Internet via an ISP. • can also use cable, cellular phone, or satellite dish • You need a computer, modem, and telephone line. Internet ISP 000-209 Intro to CS. 8/Internet

  25. Connection Speeds • Connectionspeed is the maximum speed that your modem can communicate with the ISP’s modem • a modem with a connection speed of 14.4 Kbps is much slower than a cable modem with a connection speed of 1 MBps 000-209 Intro to CS. 8/Internet

  26. 000-209 Intro to CS. 8/Internet

  27. 5. The Web • The Web is an Internet service that stores information in the form of Web pages. • A Web page is a mix of text, graphics, sound, animation, etc. • A Web page is stored in a text file on a computer linked to the Internet (and so to the Web). continued 000-209 Intro to CS. 8/Internet

  28. Each Web page is referred to by a unique URL. • URL (Uniform Resource Locator) is an Internet address of a Web page • begin with http:// • e.g. http://fivedots.coe.psu.ac.th/~ad • http://www.wsu.edu/~dee/BUDDHISM/MAHAYANA.HTM • A Web page can be linked to another one by referring to its URL (address) continued 000-209 Intro to CS. 8/Internet

  29. Related Web pages are grouped together at a Web site. • The top-level page of a Web site is sometimes called the home page. • A Web site is managed by a Web server. 000-209 Intro to CS. 8/Internet

  30. No. of Web Sites 000-209 Intro to CS. 8/Internet

  31. 6. Web Browsers • A Web browser allows a user to access Web pages at different sites. • it uses HTTP to talk to the site's Web server • HTTP is the Hypertext Transfer Protocol • You get a Web page in a Web browser by typing in its URL, or clicking on a link that goes to the page. 000-209 Intro to CS. 8/Internet

  32. MS Internet Explorer • Comes with MS Windows • Slow • Easy to attack • Does not support all the Internet standards http://fivedots.coe.psu.ac.th/~ad/ 000-209 Intro to CS. 8/Internet

  33. Free/Shareware Browsers • Firefox • PC World product of the year, 2005 • http://www.mozilla.org/products/firefox/ continued 000-209 Intro to CS. 8/Internet

  34. Opera • available on many platforms • http://www.opera.com/ http://fivedots.coe.psu.ac.th/~ad/ 000-209 Intro to CS. 8/Internet

  35. 7. Web Search Engines • A Web Search engine is a Web site which allow you to search for things on the Web: • http://www.google.com • http://www.yahoo.com • Google offers many search engines: • web pages, images, mailing lists, news, maps, cheapest online goods, academic articles, and more • the best starting point for searching 000-209 Intro to CS. 8/Internet

  36. Google (http://www.google.co.th/) 000-209 Intro to CS. 8/Internet

  37. 8. Web Portals • A Webportal is a Web site that provides a starting point for finding popular Web services. • search engines • (free) e-mail accounts • chat rooms • links to shopping, weather, news, and sports continued 000-209 Intro to CS. 8/Internet

  38. Popular Web portals include: • Yahoo! http://www.yahoo.com (best) • About.com http://www.about.com/ • America Online http://www.aol.com/ • MSN http://www.msn.com/ 000-209 Intro to CS. 8/Internet

  39. Yahoo (http://www.yahoo.com) 000-209 Intro to CS. 8/Internet

  40. Other Types of Portal • Regional • portal versions focussing on specific geographical areas (e.g. Yahoo! UK) • Government • sources for government forms, information(e.g. http://first.gov in the USA) • Enterprise • used by large corporations, serving different groups • B2C (business-to-customer/consumer),B2B (business-to-business/supplier), etc 000-209 Intro to CS. 8/Internet

  41. E-Commerce • E-commerce refers to buying products and services using the Internet. • online shoppinge.g. Amazon books (http://www.amazon.com) • online auction sitese.g. eBay (http://www.ebay.com) continued 000-209 Intro to CS. 8/Internet

  42. Individuals can set up their own e-commerce site. • Many Web hosting services and portal sites offer e-commerce enabling, which helps you build an online store. 000-209 Intro to CS. 8/Internet

  43. 9. Blogs and Blogging • A blog (weblog, web diary) is a web page which contains periodic, dated posts/writings. • Blogs can be diaries, political campaigns, technical articles, gossip, etc. • Blogging is the process of writing a blog. • Blogs are part of the blogosphere. 000-209 Intro to CS. 8/Internet

  44. 10. Web Page Content • Web pages can include multimedia elements such as sound, animation, and video. • Streamingmedia: the browser plays a media file while receiving it 000-209 Intro to CS. 8/Internet

  45. Browser Plug-ins • A plug-in is software that gives the browser the capability to view or play a specific type of file. • The Web browser maintains a list of the installed media plug-ins. continued 000-209 Intro to CS. 8/Internet

  46. A plug-in often starts a separate player or viewer to display the downloaded media. 000-209 Intro to CS. 8/Internet

  47. Typical Plug-ins • Shockwave Flash • for executing animations • Windows Media Player • for executing video and audio • Java • for safely executing Java applets (small applications embedded in Web pages) 000-209 Intro to CS. 8/Internet

  48. 11. Writing a Web Page • A Web authoring tool makes it easy to create a Web page. • a word processor-style interface • wizards • predesigned templates, style sheets • Commercial Web authoring software includes Microsoft FrontPage and Macromedia Dreamweaver. 000-209 Intro to CS. 8/Internet

  49. MS FrontPage • http://www.microsoft.com/frontpage/ 000-209 Intro to CS. 8/Internet

  50. CoffeeCup HTML Editor • Most popular free tool • http://www.coffeecup.com/html-editor/ 000-209 Intro to CS. 8/Internet