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Section 1: Internet Technologies

Section 1: Internet Technologies. Internet Overview. What is the Internet?. Collection of computers networked together Uses standards based on TCP/IP Data broken down into packets Allows for differing computer platforms to communicate Based on globally unique address for each node

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Section 1: Internet Technologies

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  1. Section 1:Internet Technologies

  2. Internet Overview

  3. What is the Internet? • Collection of computers networked together • Uses standards based on TCP/IP • Data broken down into packets • Allows for differing computer platforms to communicate • Based on globally unique address for each node • Network is global

  4. The Internet Network Computer Computer Data Data Internet Computer Data Data Data Data Computer Computer

  5. User Application TCP/IP Internet Using the Internet Computer Data Internet Internet Connection Data

  6. Computer to Access Internet: Three Requirements • Application - many available • E-Mail, Web Browser, Server, File Transfer, Video Conferencing, + Others • TCP/IP • Standard in computer operating systems • Interfaces to Internet • Internet Connection

  7. User Application TCP/IP Internet E-Mail Web Browser, Server File Transfer Protocol Video Conferencing + Others Included with Computer Operating System (usually) Internet Connection Data

  8. User Application TCP/IP Internet Internet Connection • Plain Phone Line (POTS) • Higher Speed Phone Line: ISDN, DSL • Cable Modem • Ethernet etc.

  9. Example:What is the throughput capacity of this system? 100 500 150 250 10 300 Throughput in MB/Sec Note: real Internet is very large scale and dynamic

  10. What is the World Wide Web? • Client: browser connected to Internet. • Uses hypertext and graphics to display information • Server: server software connected to Internet • Client-Server based - no platform incompatibilities (?) • Any WWW browser can connect to any WWW server (if both follow standards) • Rapid growth in capabilities of servers and clients (browsers). • Note use of standards.

  11. The World Wide Web Server Data resides on server Computer Request Received Data Sent TCP/IP Internet Data Request Sent Data Received Client clicks on hyperlink. Data received Browser Computer TCP/IP

  12. WWW and Hyperlinks • Use embedded codes to allow for hyperlinks (Hypertext Markup Language). • When viewed in browser, user does not see embedded codes. • Allows for simple point and click navigation.

  13. Browsers Increasing Sophistication • Hyperlinked text • Graphics • Plug-ins (e.g. sound, video) • Active elements (Java, ActiveX) • Operating Environment

  14. Web Pages and HTML • Hypertext Markup Language (HTML) • Uses tags that allow browser to change the format • Tools to help write HTML (Word, FrontPage etc.) • See refs on web site

  15. HTML Element • An HTML element may include a name, some attributes and some text or hypertext <tag_name> text </tag_name> or <tag_name attribute_name=argument> text </tag_name> or <tag_name>

  16. HTML Text Elements • <h1> . . . </h1> Heading 1 to heading 6 <h6> . . . </h6> • <b> . . . </b> Bold; <i> . . . </i> Italic; <u> . . . </u> Underline • Unordered List ul <ul> <li> First item in the list <li> Next item in the list </ul>

  17. HTML Hyperlink • <a href="URL"> . . . </a> Links to another file or resource • Also need <html> <head> and <TITLE> • Examples • Other elements are also defined – will be using HTML Forms later

  18. <html> • <head> • <TITLE>HTML Example</TITLE> • </head> • <body> • <H1>HTML is Pretty Easy To Learn</H1> • <P>Welcome to HTML. This is a paragraph.</P> • <IMG SRC=http://www.engineering.uiowa.edu/~pjogrady/Internet/ImagesSounds/JACKSGLOBE.gif> • <P> <A HREF = "http://www.engineering.uiowa.edu/~pjogrady/Internet/Default.htm"> • This is a hyperlink</A></P> • </body> • </html> • Put the above text in a file named *.htm or *.html (use Notepad or similar text editor.) • Open using browser • Browser interprets tags to display contents

  19. Growth in Number of Web Sites • 1992 • 50 web sites in world. • Now • 65,000 web sites added per hour.

  20. Thoughts on the Issue of Internet Overload. • The first suggests that the internet capacity is a finite resource but that users are not charged for each use. Hence Internet will be overused. • The second school of thought more optimistically suggests that the Internet can continue to grow and response time can remain reasonable. Seems to be the most accurate.

  21. Internet Traffic • Routers on the Internet continually collate the return time for test packets and this is called the ping delay (next slide) • Used as part of routing for packets

  22. Technology Change “Technology will develop in response to customer demand” Peter O’Grady • Processor (Moore’s Law) • Communications Capacity (Gilder's Law) (infrastructure and bandwidth) • More complex to forecast than processor • Estimate to be growing by factor of three per year (doubtful)

  23. From http://www.physics.udel.edu/wwwusers/watson/scen103/intel.html.

  24. From: The Economist, 2003

  25. Computer Processing Power: Moore's Law Compaq Microsoft Dell

  26. From: http://computer.howstuffworks.com/microprocessor2.htm

  27. Communications (2002 = 1) • Investment in new fiber has slumped • Estimated 95% of fiber is “dark” • Potential increase in efficiency of existing fiber.

  28. From: The Economist, 2003

  29. What are the implications of this growth in bandwidth? Potential for increasing speed of information flow and ideas. This could increase Productivity Economic growth World peace? Outsourcing (why?)

  30. Old and New Economies OLD A Little Trade B Tariffs, Regulations, Poor Communications NEW A Large Trade B Ricardo - Theory of Comparative Advantage 1817 Increased economic growth

  31. Manufacturing Output per Hour 1995-2000 Average Annual Change %

  32. World Trade Volumes From: The Economist

  33. From: The Economist

  34. Impact of E-Commerce • Impact of Business to Consumer • 5% reduction in aggregate distribution costs • 0.5 - 0.7% reduction in costs in overall economy • 63-88% of annual increase in total factor productivity in G-7 countries • Impact of Business to Business E-Commerce • “orders of magnitude higher” Source: OECD: “The Economic and Social Impacts of E-Commerce”

  35. Internet Fundamentals

  36. How do standards happen? • Standards organizations (e.g. ISO) • Usually international • Often slow • Non-proprietary • Industry Groups (e.g. bar codes) • De Facto (e.g. TCP/IP) • Result of widespread use • Can be quick to develop • Can be quick to change, proprietary, no international body to maintain standard

  37. ISO Model • The International Standards Organization, based in Geneva Switzerland • Composed of groups from various countries that set standards working towards the establishment of world-wide standards for communication and data exchange.

  38. ISO Model • Developed a Reference Model that contains specifications for a network architecture for connecting dissimilar computers. • A main goal being that of producing an open and non-proprietary method of data communication.

  39. ISO Model • This reference model, called the Open Systems Interconnect Reference Model (OSI RM), was developed in 1981 and revised in 1984.

  40. The OSI RM • Uses 7 layers, each independent of each other, to allow computers to exchange data. • To transfer a message from user A to user B, the data has to pass through the 7 layers on user's A machine, before being transmitted through the selected medium.

  41. The OSI RM • At the receiving computer of user B, the data must then pass through the 7 layers again, this time in reverse sequence before being received by user B. • For data to be transferred, it must pass through all 7 layers on both computers.

  42. The OSI RM • Each layer follows a relatively strict specification and this allows the differing layers to be produced and implemented by different concerns. • Each layer can then interface with its neighboring layers even though they may have been developed by different groups.

  43. The OSI RM • The Layers Are Arranged in Order As Follows: • Layer 7, Application Layer. • Layer 6, Presentation Layer. • Layer 5, Session Layer. • Layer 4, Transport Layer. • Layer 3, Network Layer. • Layer 2, Data Link Layer. • Layer 1, Physical Layer.

  44. The OSI RM • In spite of enormous amount of work, little of the OSI RM is in use. • This is probably due to the rise of TCP/IP

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