1. © Minder Chen, 1996-2013 Web Architecture - 1 The Architecture of Internet and WWW Web Browser Client Web Server End User HTTP TCP/IP HTML documents Internet or Intranet Benefits of the Web as a delivery mechanism: Thin clients Platform independence Easy for deployment/upgrade Based on standards

2. © Minder Chen, 1996-2013 Web Architecture - 2 Internet: The Virtual Network & Internal Structure Computer Router A Regional Network Internet NAP ISP LAN NAP: National Access Point ISP: Internet Service Provider TELCO

3. © Minder Chen, 1996-2013 Web Architecture - 3 Hosts on the Internet IP Datagram –Datagram Header Source: 15.127.9.12 (IP Address) Destination: 254.231.15.129 American Registry for Internet Numbers https://www.arin.net/ Router Total about 4.3 billion IP addresses.

4. © Minder Chen, 1996-2013 Web Architecture - 4 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 registrationhttp://www.godaddy.com edu uiuc csuci cs vax The name of a host computer with an IP address student First Level Second Level CSUCI.EDU Top country domain name.us.tv (30M).md

5. © Minder Chen, 1996-2013 Web Architecture - 5 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.

6. © Minder Chen, 1996-2013 Web Architecture - 6 Client-Server Model of http Web Server Web Client Requesting a document via a URL address Connection open Returning MIME- compliance document Connection close helper app Web contents HTML documents Images Animation Video clips Sound bites Java applets Java Scripts CGI scripts JSP Database access ASP/ASPX/PHP JSP Web Site Internet or Intranet 1 2 Static Dynamic MIME: Multipurpose Internet Mail Extension

7. © Minder Chen, 1996-2013 Web Architecture - 7 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)

8. © Minder Chen, 1996-2013 Web Architecture - 8 The Extended Framework of WWW Web Browser Client HTML Authoring Tools/Editors End User Web Master Web Designer & Publisher External Applications Non-HTTP objects ColdFusion, CGI (Perl) ASP & ASP.NET JAVA Servlet Java Server Pages Java Applet JavaScript Internet Global Reach Broad Range Web Programmer Web Server

9. HTML Sampler Web Page HTML Sampler List: Item 1 Item 2 Item 3 Name Speciality Minder Chen MIS Justin Chen Aerospace A sample of a form: <form method="post" action="http://hoohoo.ncsa.uiuc.edu/cgi-bin/post-query" > Name: Know HTML Developed by Advanced IT Consulting image list table form link

10. © Minder Chen, 1996-2013 Web Architecture - 10 HTTP (Web) Cookie First party and third party Cookies at http://on.wsj.com/LamyJX This is how most web sites used to track you and maintain online sessions.

11. © Minder Chen, 1996-2013 Web Architecture - 11 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

12. © Minder Chen, 1996-2013 Web Architecture - 12 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 usedOS Browsers usedBrowsers Robots HTTP referrer Search engines, key phrases and keywords used to find the analyzed web siteSearch engines HTTP errors Some of the log analyzers also report on who's on the site, conversion tracking, visit time and page navigation.