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The Architecture of Internet and WWW Benefits of the Web as a delivery mechanism: •Thin clients •Platform independence •Easy for deployment/upgrade •Based on standards Web Browser HTML documents HTTP TCP/IP Client End User © Minder Chen, 1996-2013 Internet or Intranet Web Server Web Architecture - 1 Internet: The Virtual Network & Internal Structure NAP ISP Computer Router A Regional Network Internet TELCO LAN NAP: National Access Point ISP: Internet Service Provider © Minder Chen, 1996-2013 Web Architecture - 2 Hosts on the Internet • IP Datagram – Datagram Header Total about 4.3 billion IP addresses. • Source: 15.127.9.12 (IP Address) • Destination: 254.231.15.129 • American Registry for Internet Numbers https://www.arin.net/ Router © Minder Chen, 1996-2013 Web Architecture - 3 Domain Name • DNS (Domain Name Server): Mapping the four octets (32-bit numeric) IP address (such as 217.156.3.14) to a domain name such as student.csuci.edu • http://www.godaddy.com for domain name registration The name of a host computer with an IP address CSUCI.EDU edu First Level csuci student uiuc cs vax Top country domain name .us .tv (30M) .md Second Level © Minder Chen, 1996-2013 Web Architecture - 4 Key Elements of Web • Hypertext: Non-linear links to anchors of the same document, or to different documents on the same or different web site. – Using HTML (HyperText Markup Language) links and anchors – Relying on URL (Uniform Resource Locators) addressing scheme • Multimedia: graphics, video, sound, etc. – Web browser can access networked hypermedia. – Hypermedia access of the web browser is facilitated by helper applications, plug-ins, or document viewers. • Network: Global reach and "Universal" access – Based on HTTP which is built on top of the TCP/IP protocol. © Minder Chen, 1996-2013 Web Architecture - 5 Client-Server Model of http 1 helper app helper app helper app helper app helper app Web Site • Requesting a document via a Web Server URL address • Connection open Internet or Intranet Web Client Static 2 Dynamic • Returning MIMEcompliance document • Connection close Web contents • HTML documents • Images • Animation • Video clips • Sound bites • Java applets • Java Scripts • CGI scripts • JSP • Database access • ASP/ASPX/PHP • JSP MIME: Multipurpose Internet Mail Extension © Minder Chen, 1996-2013 Web Architecture - 6 HTTP • HTTP: HyperText Transfer Protocol • Characteristics: – Runs on top of TCP/IP (Transmission Control Protocol/Internet Protocol) – Has a comprehensive addressing scheme, i.e. URL – An extensible and open representation for data type, using MIME header – Has a stateless protocol. There is no memory between client connections. Cookies are used to track users. – Is efficient – Is portable – Possible extensions, Secure HTTP (SHPPT), SSL. (https://URL) © Minder Chen, 1996-2013 Web Architecture - 7 The Extended Framework of WWW HTML Authoring Tools/Editors Web Browser Web Designer & Publisher External Applications Non-HTTP objects Web Programmer • ColdFusion, • CGI (Perl) • ASP & ASP.NET • JAVA Servlet • Java Server Pages • Java Applet • JavaScript Internet Global Reach Broad Range Client End User © Minder Chen, 1996-2013 Web Server Web Master Web Architecture - 8 <html> <head> <title> HTML Sampler Web Page </title> </head> <body> <h1>HTML Sampler</h1> <img src="eyes.gif"><br> <b> List: </b> <ul> <li> Item 1 <li> <font size=+2>Item 2</font> <li> <i>Item 3</i> </ul> <table border=1> <tr> <th> Name</th> <th>Speciality </th> </tr> <tr> <td> Minder Chen</td> <td>MIS </td> </tr> <tr> <td> Justin Chen</td> <td>Aerospace </td> </tr> </table> <p> A sample of a form: <form method="post" action="http://hoohoo.ncsa.uiuc.edu/cgi-bin/post-query" > Name: <input type="text" size=20> <br> <input type="checkbox" name="html" value="YES"> Know HTML <br> <b><input type="submit" value="Submit your data"></b> </form> <hr> Developed by <a href="http://www.erols.com/aitc/"> Advanced IT Consulting</a> </body></html> HTTP (Web) Cookie This is how most web sites used to track you and maintain online sessions. • First party and third party Cookies at http://on.wsj.com/LamyJX © Minder Chen, 1996-2013 Web Architecture - 10 Clickstream • Hit – any Web server request that generates a log file entry. A page has many elements (html, gifs), each generating a hit. • Page – Web server file that is sent to client user agent, usually a browser. • Session – all actions (i.e. requests, resets) made in single visit, from entry until logout or time out (e.g., 20 minutes of no activity). • Visitor – a user or bot/spider/crawler that makes requests at a site. Can be new, returning, registered, anonymous • Buyer – visitor that purchases something • Customer – a visitor that registers (sometimes defined as buyer) • Conversion – rate at which visitors transition to desired state • (buyers, customers, registered, started checkout) • Host – remote machine, identified by IP address, used for visit. • Referrers – page that provides a link to another page. Can be internal or external © Minder Chen, 1996-2013 Web Architecture - 11 Web Log Analysis • • • • • • • • • • • • • • • • Number of visits and number of unique visitors Visits duration and last visits Authenticated users, and last authenticated visits Days of week and rush hours Domains/countries of host's visitors. Hosts list Number total pageviews Most viewed, entry and exit pages Files type OS used Browsers used Robots HTTP referrer Search engines, key phrases and keywords used to find the analyzed web site HTTP errors Some of the log analyzers also report on who's on the site, conversion tracking, visit time and page navigation. © Minder Chen, 1996-2013 Web Architecture - 12
