Transcription of Lecture Notes 1: The Internet and World Wide Web
1 Page 1 CSE 190 M Slides: Internet /WWW04/05/2007 11:24:51 AMfile://localhost/C:/Documents%20and%20 Settings/stepp/My%20 Documents/cse190 Notes 1:The Internet and World Wide WebCSE 190 M (Web Programming), Spring 2007 University of WashingtonReading: Sebesta Ch. 1 sections - , - , , is the Internet ?A "series of tubes" (1, 2)Stevens Internet "series of tubes"Search powered byVideo Series of TubesSenator Ted Stevens talking aboutthe Net Neutrality BillJul 17, many internetsare there, anyway?bush rumors internetsSearch powered byVideo Rumors on the internetsGeorge W. Bush clip with thefamous: "I hear there're rumors onFeb 10, 2 CSE 190 M Slides: Internet /WWW04/05/2007 11:24:51 AMfile://localhost/C:/Documents%20and%20 Settings/stepp/My%20 Documents/cse190 InternetWikipedia: connection of computer networks using the Internet Protocol (IP)What's the difference between the Internet and the World Wide Web (WWW)?
2 The Web is the collection of web sites and pages around the World ; the Internet is larger and also includesother services such as email, chat, online games, Protocol (IP)a simple protocol for attempting to send data between two computerseach device has a 32-bit IP addressaddresses written as four 8-bit numbers (between 0 and 255) out your Internet IP address: out your local IP address:in a terminal, type:ipconfig(Windows) orifconfig(Mac/Linux)Page 3 CSE 190 M Slides: Internet /WWW04/05/2007 11:24:51 AMfile://localhost/C:/Documents%20and%20 Settings/stepp/My%20 Documents/cse190 Control Protocol (TCP)adds multiplexing, guaranteed message delivery on top of IPmultiplexing: multiple programs using the same IP addressport: a number given to each program or serviceport 80: web browserport 25: emailport 22: sshport 5190: AOL Instant Messengermore common portssome programs (games, streaming media programs) use simpler UDPprotocol instead of TCPD omain Name System (DNS)a set of servers that map written names to IP systems maintain a local cache called a hosts fileWindows:C:\Windows\system32\drivers\ etc\hostsMac:/private/etc/hostsLinux:/et c/hostsPeople and organizationsWorld Wide Web Consortium (W3C): web standardsInternet Engineering Task Force (IETF): Internet protocolstandardsInternet Corporation for Assigned Names and Numbers (ICANN): decides top-level domain namesWeb Servera computer running web server software that listens for web pagerequests on TCP port 80popular web server software :Apache: Internet Information Server (IIS)available as part of Windows XP (directions)Page 4 CSE 190 M Slides: Internet /WWW04/05/2007 11:24.
3 51 AMfile://localhost/C:/Documents%20and%20 Settings/stepp/My%20 Documents/cse190 Browsera software application that displays web pagespopular web browser software :Mozilla Firefox: Internet Explorer (IE): part ofWindowsApple Safari: part of Mac OS XOpera: Transport Protocol (HTTP)the set of commands understood by a web server and sent from a browsersome HTTP commands (your browser sends these internally):GETfilename: downloadPOST filename: send a web form responsePUTfilename: uploadsimulating a browser with a terminal window:$ telnet 80 Trying to ( ).Escape character is '^]'.GET <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML .."> <html>..HTTP error codesthe web server returns a special "error code" number to the browser, possibly followed by an HTML documentcommon error codes:Number Meaning200OK301-303page has moved (permanently or temporarily)403you are forbidden to access this pagePage 5 CSE 190 M Slides: Internet /WWW04/05/2007 11:24:51 AMfile://localhost/C:/Documents%20and%20 Settings/stepp/My%20 Documents/cse190 not found500internal server errorcomplete list of error codesUniform Resource Locator (URL)an identifier for the location of a document on a web sitea basic URL: ~~~~ ~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~protocol host pathupon entering this URL into the browser, it would.
4 Ask the DNS server for the IP address to that IP address at port 80ask the server toGET /info/ the resulting page on the screenMore advanced URLsanchor: jumps to a given section of a web #downloadsthe above URL then jumps downward to a part of the page labeleddownloadsport: for web servers on ports other than the default 80 :8080/ string: a set of parameters passed to a web +failure&start=10the above URL asks the server run the program namedsearchand passit two parameters:q(set to"miserable+failure")start(set to10)Page 6 CSE 190 M Slides: Internet /WWW04/05/2007 11:24:51 AMfile://localhost/C:/Documents%20and%20 Settings/stepp/My%20 Documents/cse190 programming technologiesHypertext Markup Language (HTML): used for writing web pagesXHTML: A newer, more rigidly standardized specification of HTMLC ascading Style Sheets (CSS): supplies stylistic info to web pagesJavascript: allows interactive and programmable web pagesAsynchronous Javascript and XML (AJAX): allows fetching of web documents in the background forenhanced web interactionGoogle AJAX Search API: embeds Google services in web pagesPHP Hypertext Processor (PHP): allows the web server to create pages dynamicallyStructured Query Language (SQL): interaction with databases
