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Digital Media

Digital Media. Dr. Jim Rowan ITEC 2110. webpages and other stuff. DHCP:. your browser (Safari)(client). yahoo.com (server) 235.01.30.240. your computer. The Internet. walmart.com (server) 100.43.153.07. Domain Name System (DNS). webpages and other stuff. DHCP: 135.10.34.222.

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Digital Media

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  1. Digital Media Dr. Jim Rowan ITEC 2110

  2. webpages and other stuff DHCP: your browser (Safari)(client) yahoo.com (server) 235.01.30.240 your computer The Internet walmart.com (server) 100.43.153.07 Domain Name System (DNS)

  3. webpages and other stuff DHCP: 135.10.34.222 your browser (Safari)(client) yahoo.com (server) 235.01.30.240 your computer ISP The Internet walmart.com (server) 100.43.153.07 Domain Name System (DNS)

  4. webpages and other stuff DHCP: 135.10.34.220 your browser (Safari)(client) yahoo.com (server) 235.01.30.240 http://www.yahoo.com your computer The Internet walmart.com (server) 100.43.153.07 Domain Name System (DNS) http://www.yahoo.com = 235.01.30.240

  5. webpages and other stuff /index.html DHCP: 135.10.34.222 your browser (Safari)(client) yahoo.com (server) 235.01.30.240 http://www.yahoo.com your computer The Internet walmart.com (server) 100.43.153.07 Domain Name System (DNS) http://www.yahoo.com = 235.01.30.240

  6. IPv4 & IPv6How many computers? • IPv4 http://en.wikipedia.org/wiki/Internet_Protocol_version_4 FF:FF:FF:FF 255.255.255.255 256 ** 4 = 4,294,967,296 computers • IPv6 http://en.wikipedia.org/wiki/IPv6_address FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF 65536:65536:65536:65536:65536:65536:65536:65536 65536 ** 8 = 3.4e+38 computers: how big is that?==>

  7. How big is that? Circumference of the earth = 25,000 miles 25,000 x 5280 x 12 = 1,584,000,000 inches Circumference = pi x diameter Circumference of the earth = pi x 2 x radius 1584000000 = 3.14 x 2 x radius radius =252,229,299 inches Surface area of the earth = 4 x pi x radius**2 Surface area of the earth = 4 x 3.14 x 252,229,299**2 Surface area of the earth = 7.99e+17 sq inches 3.4e+38 computers / 7.99e+17 sq inches = 4.255e+20 So… that’s 4.255e+20 computers per square inch of surface area That should cover it!

  8. Web Protocols • Protocols define the rules to be followed in a conversation • who talks first • what is acceptable to request • what are acceptable responses to a request • syntax is the actual form of each interaction • HTTP - Hyper Text Transfer Protocol • identifies it as a web page request • FTP - File Transfer Protocol • identifies it as a file that needs to be downloaded • SMTP - Simple Mail Transport Protocol • identifies it as pertaining to email

  9. Parts of the Uniform Resource Locator URL • Three parts: • Specifies the protocol to use • HTTP • FTP • SMTP • The Domain Name • www.ggc.edu • Directory information used by the server to find the file to transmit • This can be • directory and pages • data to be handed to a program

  10. How to start your own website • You have to buy a Domain Name from a Domain Name supplier • register.com • godaddy.com • The Domain Name supplier • pay by the year • set up domain-name-to-IP mapping • may provide some storage space for your web pages using their IP

  11. …or to start a website • You could have your own server • Macs come with servers built in • You must have a FIXED IP from your ISP • not really but it makes life MUCH simpler • You still need a Domain Name from a Domain Name Supplier • pay by the year • set up domain-name-to-IP mapping

  12. Looking up URLs and IPs • whois IP and Domain lookups http://ip-lookup.net/ • look up pondliner.com domain name to get IP • connect to pondliner.com using the IP address • see who owns pondliner.com • http://www.register.com/whois.rcmx

  13. WebCrawlers • Once looked and collected email addresses to sell to spammers • Simple to do • request a page • look through the text of the page for something @ something.something • Can be defeated by using unfriendly-to-robot-code like: jrowan (at) GGC (dot) USG (dot) EDU • humans can read this just fine!

  14. Search Engines • Web crawlers look through the web looking for keywords • Then they build a catalog of keywords • You enter a keyword in the engine • It looks at its table • It sends you the URLs associated with the keyword • GOOGLE extends this by including the number of links that point to that particular page

  15. And now for a little history...

  16. A brief history • Ward Cunningham • invented the WikiWikiWeb • www pages quickly editable by its users • Wiki is Hawaiian for “fast”

  17. A brief history • Tim Berners-Lee • invented the World Wide Web • 1980 built the first web server • mid 1980s worked with hypertext • 1988- “I just had to take the hypertext idea and connect it to the TCP and DNS ideas and ta-da! the World Wide Web!” • wrote the first web browser (the client)

  18. Randy Pausch HCI pioneer Disney Imagineering CMU: Entertainment Technology Center Creator of the Alice language

  19. Randy Pausch The Last Lecture: Really Achieving Your Childhood Dreams http://www.youtube.com/watch?v=ji5_MqicxSo

  20. And now…Alan Kay

  21. Alan Kay’s 1968 vision of how computing COULD be: The Dynabook

  22. Before Alan Kay at XEROX PARC… The command driven computer interface: Remember the Disk Operating System? (probably not!)

  23. Alan Kay’s 1970’s XEROX PARC work • The Graphical User Interface GUI • But Xerox corporate didn’t think it was important

  24. which opens the door for Steven Jobs • Macintosh 1984 • …and personal computing as we know it is born

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