Digital Media Dr. Jim Rowan ITEC 2110

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

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

yahoo.com (server) The Internet walmart.com (server) DHCP: your computer your browser (Safari)(client) Data Name System (DNS) = webpages and other stuff

yahoo.com (server) The Internet walmart.com (server) /index.html DHCP: your computer your browser (Safari)(client) Data Name System (DNS) = webpages and other stuff

How to start a website You have to buy a Domain Name –register.com –godaddy.com The Domain Name supplier –pay by the year –may provide some storage space for your web pages using their IP –probably get accounts with it –will allow you to configure your site set up domain-name-to-IP mapping

Let’s look at LINKS notice that the links are distinguished from regular text (underlined and color) also... once used, they turn a different color here the nodes connected by links are only 1 level deep is usually the deepest that is recommended

more LINKS... between pages into pages within pages

Disorientation.. Where am I? –URL is SOMETIMES useful... Example: –Why just sometimes? dynamically generated content like PHP, Perl, CGI webpage can be different each time you visit it Where was I? –browsers have “back” buttons –pages can have embedded links that take you back –browser history works without user interaction –browser bookmarks work with user interaction –use search engine and remember search strings

Finding your way around... Bookmarks User-built –indices and links can be built by hand –people search the web and keep useful indexes making them part of the site –may rely on the user to search and rate sites Indices Machine-built –indices and links are built using spiders, robots or WebCrawlers –these are programs that search the web looking for content

WebCrawlers Once looked and collected addresses to sell to spammers Simple to do –request a page –look through the text of the page for 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!

Search Engines Search web pages 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

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

Parts of the URL Has three parts: –Specifies the protocol to use HTTP FTP SMTP –The Domain Name –Other defining stuff directory info and pages data to be handed to a program

-can have two responses -assumes index.html yielding web page -assumes you want a directory list yielding a list of the contents of the directory: CV.html index.html publications.html Other defining stuff... directory info and pages

ebaymotors/ws/eBayISAPI.dll ?ViewItem&item= & ssPageName=ADME:X:AAQ:MOTORS: =747808&wban=99999&day=31&month=3&year=2008&sear chtype=zip search?hl=en&q=tim+berners-lee&btnG=Google+Search Other defining stuff... data to be handed to a program

And now for a little history...

A brief history Tim Berners-Lee (not al gore) –invented the internet –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!”TCPDNS –wrote the first web browser (the client)

Command driven computer interface

GUI –Alan Kay

GUI –Alan Kay XEROX PARC 1970’s

GUI –Alan Kay XEROX PARC 1970’s –Steven Jobs Macintosh 1984

Outside Reading