Introduction to communication

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Introduction to communication

  1. 1. מערכות מידע האוניברסיטה העברית – מוטי צוילינג
  2. 2. מבוא לתקשורת מחשבים ואינטרנט
  3. 3. Course Outline <ul><li>Internet </li></ul><ul><li>Unix </li></ul><ul><li>Word processing </li></ul><ul><li>HTML </li></ul><ul><li>Spreadsheets </li></ul><ul><li>Presentations </li></ul><ul><li>Graphics </li></ul><ul><li>Peripherals </li></ul>
  4. 4. The Internet: technology and services
  5. 5. Internet Technologies
  6. 6. The UNIX Connection <ul><li>The Internet has grown out of UNIX Operating System </li></ul><ul><li>Some Internet terms (email address) and services (FTP) become more clear after we cover UNIX </li></ul>
  7. 7. The Internet: A Network of Networks <ul><li>The Internet is an interconnected network of thousands of networks linking academic, research, government, and commercial institutions. </li></ul>
  8. 8. Networks Near and Far <ul><li>There are two general types of computer networks: </li></ul><ul><ul><li>WAN (Wide Area Network) </li></ul></ul><ul><ul><li>LAN (Local Area Network) </li></ul></ul>
  9. 9. LAN (Local Area Network) <ul><li>A LAN is a network in which the computers are physically close to each other </li></ul><ul><ul><li>LAN networks are usually set up to share peripherals, such as printers and network servers </li></ul></ul><ul><ul><li>Each computer and shared peripheral is a node on the LAN </li></ul></ul>
  10. 10. <ul><li>A WAN is a network in which the computers are a great distance from one another </li></ul><ul><ul><li>Connections are made via telephone lines, satellites, and/or microwave relay towers </li></ul></ul><ul><ul><li>Each network site is a node </li></ul></ul>WAN (Wide Area Network)
  11. 11. WAN (Wide Area Network) <ul><li>WANs are often made up of LANs </li></ul>
  12. 12. <ul><li>A modem is needed to connect a computer to a phone line </li></ul><ul><li>The computer communicates with digital signals </li></ul><ul><li>The telephone system was designed to transmit voice signals which are analog </li></ul>Communication with Modem
  13. 13. Client/Server Model
  14. 14. Internet Protocols <ul><li>TCP/IP (Transmission Control Protocol/Internet Protocol) is the protocol at the heart of the Internet. </li></ul>
  15. 15. Internet Protocols <ul><li>TCP/IP translates into: </li></ul><ul><ul><li>TCP (transmission control protocol) breaks messages into packets. </li></ul></ul><ul><ul><li>IP (Internet protocol) is the addressing for the packets. </li></ul></ul><ul><ul><li>computer in the Internet ( host) is identified by IP address (e.g. 128.214.9.225) </li></ul></ul><ul><ul><li>IP addresses run out </li></ul></ul>
  16. 16. Internet Addresses <ul><li>An Internet address is made up of two parts separated by the @ symbol: </li></ul><ul><li>the person’s user name </li></ul><ul><li>the host name </li></ul><ul><li>The host is named using DNS (domain name system), which translates IP addresses into a string of names . </li></ul>
  17. 17. Internet Addresses <ul><li>An Internet address includes: [email_address] </li></ul><ul><ul><li>username is the person’s “mailbox” </li></ul></ul><ul><ul><li>hostname is the name of the host computer and is followed by one or more domains separated by periods: </li></ul></ul><ul><ul><ul><li>host.subdomain.domain </li></ul></ul></ul><ul><ul><ul><li>host.domain </li></ul></ul></ul><ul><ul><ul><li>www.cs.helsinki.fi </li></ul></ul></ul><ul><ul><ul><li>[email_address] ( [email_address] alias) </li></ul></ul></ul>
  18. 18. Internet Addresses <ul><li>Top level domains include: </li></ul><ul><li>.edu - educational sites </li></ul><ul><li>.com - commercial sites </li></ul><ul><li>.gov - government sites </li></ul><ul><li>.mil - military sites </li></ul><ul><li>.net - network administration sites </li></ul><ul><li>.org - nonprofit organizations </li></ul>
  19. 19. Intranets <ul><li>Intranets – internal closed networks of organizations that are designed using the same technology as the Internet. </li></ul><ul><li>Firewalls - used to prevent unauthorized communication and secure sensitive internal data. </li></ul><ul><li>Virtual Private Networking (VPN) -- a way to access intranets from public Internet </li></ul>
  20. 20. Internet Services
  21. 21. The World Wide Web: Browsing the Web <ul><li>WWW is a distributed browsing and searching systems developed by CERN. </li></ul><ul><li>Use hypertext links and navigational aids to explore information on the Internet. </li></ul>
  22. 22. Web Addresses <ul><li>URL (Uniform Resource Locator): addresses for the World Wide Web. </li></ul><ul><li>http (hypertext transfer protocol): the protocol of the WWW </li></ul>
  23. 23. Searching the Web <ul><li>A directory (also an index ) is a hierarchical catalog of Web sites compiled by researchers. </li></ul>
  24. 24. Searching the Web <ul><li>A search engine offers a more complete database of what is one the WWW. A software robot or spider retrieves the entries according to key word queries. </li></ul>
  25. 25. Email on the Internet <ul><li>Email (one-on-one communication). </li></ul><ul><li>Pine - UNIX-based mail program. </li></ul><ul><li>MIME - Multipurpose Internet Mail Exchange - allows you exchange files through email. </li></ul>Outlook express and Netscape provide more advanced mail readers
  26. 26. Disadvantages of Email <ul><li>Works only if the recipient responds </li></ul><ul><li>Authentication is not ensured </li></ul><ul><li>Email is not private </li></ul><ul><li>Can be overwhelming (SPAM) </li></ul><ul><li>Both filter out many human components of communication </li></ul>
  27. 27. Mailing Lists and Newsgroups <ul><li>Email is a valuable tool for one-to-one communication </li></ul><ul><li>Mailing lists allow you to participate in email discussion groups on special-interest topics. </li></ul><ul><li>Usenet Newsgroups are virtual bulletin boards that you access with a news reader </li></ul>
  28. 28. Other email features <ul><li>Attachments (one MB files are ok) </li></ul><ul><li>Filters </li></ul><ul><li>Ignore sender </li></ul><ul><li>Group by conversation </li></ul><ul><li>Work offline </li></ul><ul><li>Encryption and signature </li></ul>
  29. 29. Remote Access and File Transfer <ul><li>The most popular use of the Internet is information discovery and retrieval. Because the Internet is unorganized, you can use the following tools: </li></ul><ul><ul><li>Telnet : for remote login to other computers. </li></ul></ul><ul><ul><li>FTP : file transfer protocol; transfer files from remote computers. </li></ul></ul><ul><ul><li>SSH : secure remote login and file transfer </li></ul></ul>
  30. 30. Paging and chatting <ul><li>Talk is a UNIX program that allows you to carry on a split-screen communication </li></ul><ul><li>Internet relay chat (IRC) allows several users to type simultaneously </li></ul><ul><li>ICQ (I seek you): user-friendly messaging system </li></ul><ul><ul><li>Microsoft Messenger is a similar tool </li></ul></ul>
  31. 31. Streaming <ul><li>Listen to music from live radio stations </li></ul><ul><li>Using RealPlayer or Microsoft Media Player </li></ul><ul><li>E.g. www.yle.fi provides links to several life stations </li></ul><ul><li>You can even find live air traffic control </li></ul><ul><ul><li>Pilots talking to a dispatcher </li></ul></ul>
  32. 32. File sharing <ul><li>Search and download files like latest hits (mp3), blockbuster movies (mpeg), latest software packages (zip),pictures... </li></ul><ul><li>Make your own files available to others </li></ul><ul><li>Tools like Gnutella or Napster </li></ul><ul><li>Difficult for authorities to snap these systems to their distributed nature </li></ul>
  33. 33. Real-Time Communication <ul><li>Video telephony (see, hear, and type to another person). </li></ul><ul><li>MBONE - Multicast Backbone – centralized distribution </li></ul><ul><li>NetMeeting – works over ”off-the-shelf” Internet </li></ul>
  34. 34. <ul><li>Users connect (usually for a fee) to a variety of on-line databases </li></ul><ul><li>On-line databases include: </li></ul><ul><ul><li>current stock market status </li></ul></ul><ul><ul><li>digital libraries </li></ul></ul><ul><ul><li>banking </li></ul></ul><ul><ul><li>shopping </li></ul></ul>E-Commerce
  35. 35. Online banking <ul><li>Provided in Finland by all major banks </li></ul><ul><li>E.g. in Leonia costs less than any other service package </li></ul><ul><li>You get a customer number and a PIN code to log-in at their web site </li></ul><ul><li>You get a challenge-response table of codes </li></ul><ul><li>All connections are encrypted </li></ul><ul><li>Within the same bank money are moved instantly, otherwise it takes a couple of days </li></ul>
  36. 36. Rules of Thumb: On-line Survival Tips <ul><li>Protect your privacy </li></ul><ul><li>Cross-check on-line information sources </li></ul><ul><li>Netiquette </li></ul><ul><li>Avoid information overload </li></ul>

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