The Internet


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The Internet

  1. 1. Chapter 9<br />THE INTERNET<br />
  2. 2. RECAP: Computer Networks<br />LAN<br />WAN<br />
  3. 3. HARDWARE<br />Hub:<br />LAN hardware that transmits data to the nodes on the LAN “rude”. <br />Switch:<br />Hardware connectivity through which data travels. More efficient. keeps a record of the MAC addresses of all the devices connected to it. <br />
  4. 4. Transmission Line Types, Uses, and Speed<br />
  5. 5. WHAT IS INTERNET?<br />A network of networks, joining many government, university and private computers together and providing an infrastructure for the use of E-mail, bulletin boards, file archives, hypertext documents, databases and other computational resources<br />The vast collection of computer networks which form and act as a single huge network for transport of data and messages across distances which can be anywhere from the same office to anywhere in the world.<br />Written by William F. Slater, III<br />1996<br />President of the Chicago Chapter of the Internet Society<br />
  6. 6. History of THE internet<br />1969 : ARPANET was born. 4 nodes were inter-connected: UCLA,SRI,UCSB, U. of Utah Charley Kline from UCLA sent 1st packet.<br />1972 : First computer-to-computer chat program at UCLA.<br />1975 : First mailing list was created by Steve Walker.<br />1984 : DNS (Domain Name System) was introduced.<br />1988 : First Internet Worm.<br />1990 : AOL, CompuServe provided dial-up service.<br />1991 : WWW was created by Tim Berners-Lee from CERN<br />1994 : Commercial network. Shopping mall. Can order pizza online.<br />1998 : 2M domain names registered. Compaq bought for $3.3M. Google founded<br />2003 : Facebook launched<br />
  7. 7. <ul><li>A global network of computers that communicate using a common language (network of networks)
  8. 8. Internet is composed of two parts: the infrastructure (hardware), and the software (applications and protocols)
  9. 9. Hardware:
  10. 10. cables, routers, computers, and servers.
  11. 11. Software:
  12. 12. applications, programming languages, databases, and protocols that make communication</li></ul>THE INTERNET<br />
  13. 13. Internet characteristics<br />The power of the Internet:<br />1. Ubiquity<br />2. Low cost<br />3. Global Reach<br />4. Open and Shared ownership<br />5. Richness – complexity and content of the message <br />6. Interactivity<br />
  14. 14. WWW<br /><ul><li>The world wide web is a sophisticated system for universal information capture and delivery
  15. 15. The world wide web consortium (W3C) definition of the web: "The World Wide Web is the universe of network-accessible information, an embodiment of human knowledge"
  16. 16. Provides information access in ways not previously possible
  17. 17. Hyperlinked (Hypertext)
  18. 18. Graphical user interface
  19. 19. Pictorial and non-text information
  20. 20. Information that changes rapidly
  21. 21. Immediate access
  22. 22. Anyone can author a web site
  23. 23. Multi-user access to the same information (try that with a book)
  24. 24. Easily searchable information</li></li></ul><li>The functionality of the WWW is based on 3 main standards:<br />URL (Universal Resource Locator)<br />HTML (Hypertext Markup Language)<br />HTTP (Hypertext transfer Protocol)<br />
  25. 25. The Universal Resource Locator (URL)<br />Each page of information on the web has a unique address called the URL at which it can be found<br /><br />The document can be obtained using the Hypertext Transfer Protocol (HTTP)<br />Host Name - The Name of Web Server<br />Path to the Web Page<br />Denotes that the File is Written in HTML<br />HyperText Markup Language<br />File Name<br />1<br />2<br />3<br />File Name<br />Protocol<br />Host Name<br />
  26. 26. HTML<br />HTML is a universal, simple language for formatting text. It also allows embedding of graphics, and linking of documents via ‘hyperlinks’.<br />‘Hypertext’ documents allow readers to freely move around the document, following links to subjects of interest.<br />HTML is a language that is used to specify the structure of documents for retrieval across the Internet using browsers.<br />
  27. 27. HTTP<br />The standard Web transfer protocol is HTTP (HyperText Transfer Protocols). It is used for document exchange between servers and clients (typically browsers) in the WWW.<br />To retrieve a document, the client first sends a request to the web server and waits for a reply<br />An HTTP daemon/service (a program that waits for http requests) on the server then handles the request and the document is sent to the client (over a connection established using TCP/IP – Transmission Control Protocol / Internet Protocol)<br />We recall from previous lectures, that a Protocol is “Agreed upon sets of rules that provide order to a system or situation.” In this case, a set of rules/standards for communicating on the Internet.<br />
  28. 28. Key Digital Networking Technologies<br /><ul><li>Packet switching
  29. 29. Method of slicing digital messages into parcels (packets), sending packets along different communication paths as they become available, and then reassembling packets at destination</li></li></ul><li>Packet-Switched Networks and Packet Communications<br />
  30. 30. TCP/IP<br />TCP = TRANSMISSION<br /> CONTROL<br /> PROTOCOL<br />(Breaks messages into packets,<br />Checks the integrity of incoming <br />Packets and reassembles them)<br />IP = INTERNET<br /> PROTOCOL<br />(routes packets around<br />the Internet)<br />
  31. 31. WWW: What is it?<br />Is a distributed collection of hypermedia documents that are inter-linked together. Web servers store the information (text, images, sound clips, video clips), and Web clients or browsers access this information. <br />Domain addresses are governed by the standard Universal Resource Locator (URL) and end in suffixes that indicate the type of domain ownership.<br />i.e commercial sites end in .com, not-for profit entities use the .org suffix, government (.gov)<br />
  32. 32. <ul><li>The Domain Name System:
  33. 33. Converts IP address to domain names
  34. 34. Hierarchical structure top is root domain, followed by top-level domains, second-level domains, and third-level domains</li></ul>Example:<br />Domain name:<br />IP:<br />Convert Domain Name to IP address<br />Internet Addressing and Architecture<br />The Domain Name System is a hierarchical system with a root domain, top-level domains, second-level domains, and host computers at the third level.<br />
  35. 35. Internet Addressing and Architecture<br /><ul><li>Internet Architecture and Governance
  36. 36. The Internet Corporation for Assigned Names and Numbers (ICANN), assigns IP addresses
  37. 37. The World Wide Web Consortium (W3C), sets hypertext markup language and other programming standards for the web</li></li></ul><li>Client-Server Relationship<br />Client<br />issues HTTP requests<br />process documents<br />displays documents<br />Server<br />responds to HTTP requests<br />
  38. 38. Server responds<br />Client makes requests<br />Client-Server Architecture<br />SERVER<br />INTERNET<br />
  39. 39. Client/Server Computing on the Internet<br />Client computers running Web browser and other software can access an array of services on servers over the Internet. These services may all run on a single server or on multiple specialized servers.<br />