_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications1  Wiley and the book authors, 2001 E-Commerce: Fundamentals and Applications Chapter 2 : Internet and World Wide Web

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications2  Wiley and the book authors, 2001 Outline An Overview of the internet Brief history of the web Web system architecture Uniform resource locator Overview of the hypertext transfer protocol Hypertext Transfer Protocol(HTTP) Generation of dynamic web pages Cookies HTTP/1.1

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications3  Wiley and the book authors, 2001 Basic Network Architecture R R R Internet ISP modem Private network R : Router ADSL Dedicated Connection

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications4  Wiley and the book authors, 2001 Layered Model for the Internet Application Layer Link Layer Network Layer Transport Layer

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications5  Wiley and the book authors, 2001 Processing at Each Layer Application Layer  Application Data Application Header IP Header Link Header Application Header TCP Header Link Layer  Application Header TCP Header Application Data TCP Layer     Application Header TCP Header IP Header Application Data IP Layer  Application Data

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications6  Wiley and the book authors, 2001 Transfer of Packets IP Link IP Link Host AHost B Application data Application data Application TCP IP Link Application TCP IP Link

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications7  Wiley and the book authors, 2001 Different Internet Access Methods Access methodMaximum data rate Telephone modem24-56 Kbps Ethernet (Local area network)10/100/1000 Mbps Integrated Services Digital Network Basic Rate Interface (ISDN BRI) 56 – 128 Kbps Cable modem30 Mbps (theoretical) 1.5 Mbps shared (practical) Asymmetric Digital Subscriber Line (ADSL)1.5 Mbps - 9 Mbps (from network to users) 128 Kbps – 9 Mbps (from users to network) Wireless local area network (IEEE )1-56 Mbps

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications8  Wiley and the book authors, 2001 Simple Routing Example Destination Network Next hop R R3 : R1 R3 R2 ……

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications9  Wiley and the book authors, 2001 Common Application Layer Protocols ProtocolPurpose Simple mail transfer protocolSupport services File transfer protocolSupport file transfer services TELNETAllow users to log in remote host Hypertext transfer protocolSupport communications between a Web client and a Web server

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications10  Wiley and the book authors, 2001 Part of the DNS tree ….. Root comedugovmilorgnethkjp vbs www

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications11  Wiley and the book authors, 2001 Web System Architecture Database Web Client Internet Web Server and Application Server

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications12  Wiley and the book authors, 2001 URL Used to identify web pages  protocol://domain_name:port/directory/resource Example:  General format: 

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications13  Wiley and the book authors, 2001 Request Methods in HTTP/1.0 GET HEAD POST

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications14  Wiley and the book authors, 2001 General Headers in HTTP/1.0

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications15  Wiley and the book authors, 2001 General Headers in HTTP/1.0 Date Pragma Request Headers in HTTP/1.0 Authorization From If-modified-Since Referer User-Agent

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications16  Wiley and the book authors, 2001 Entity Header in HTTP/1.0 Allow Content Encoding Content Length Content Type Expires Last-Modified

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications17  Wiley and the book authors, 2001 Commonly Used Status Codes in HTTP/1.0 Status codeStatus message 200OK 201Created 204No content 301Moved Permanently 302Moved Temporarily 304Not Modified 400Bad Request 401Unauthorized 403Forbidden 404Not Found

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications18  Wiley and the book authors, 2001 Commonly Used Response Header in HTTP/1.0 Location Server WWW-Authenticate

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications19  Wiley and the book authors, 2001 Generating dynamic web pages Attach names and values at the end of the URL using a query string: ?name 1 =value 1 & name 2 =value 2 &….& name N =value N Example:   GET /servlet/booksearch?title=ecommerce&year=2000 HTTP/1.0

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications20  Wiley and the book authors, 2001 Cookies Invented by Netscape. Save state data at client side. Visit Standardized in RFC2109 Server  Set-Cookie: Name=Value Client  Cookie: Name=Value

_______________________________________________________________________________________________________________ E-Commerce: Fundamentals and Applications21  Wiley and the book authors, 2001 HTTP/1.1 Persistent connection Pipelining Efficient use of IP addresses Best support for:  caching  authentication  language  encoding More request methods