ELECTRONIC COMMERCE- Framework, Technologies and Applications © Tata McGraw-Hill 1 Electronic Commerce: Information Distribution and Messaging

ELECTRONIC COMMERCE- Framework, Technologies and Applications © Tata McGraw-Hill 2 World Wide Web Developed at CERN (European Laboratory for Particle Physics) Developed at CERN (European Laboratory for Particle Physics) Purpose was to share multimedia documents across computers in a seamless fashion. Purpose was to share multimedia documents across computers in a seamless fashion. Tim Berner-Lee proposed a system architecture where servers will manage the document and clients running on remote machines will access and render these documents. Tim Berner-Lee proposed a system architecture where servers will manage the document and clients running on remote machines will access and render these documents. The system proposed HyperText Markup Language for writing the documents. The HTML documents could specify links to other documents, using HyperText mechanism, by embedding their URLs. The system proposed HyperText Markup Language for writing the documents. The HTML documents could specify links to other documents, using HyperText mechanism, by embedding their URLs. Hyper Text Transfer Protocol was proposed as the protocol among clients and servers. Hyper Text Transfer Protocol was proposed as the protocol among clients and servers.

ELECTRONIC COMMERCE- Framework, Technologies and Applications © Tata McGraw-Hill 3 World Wide Web System

ELECTRONIC COMMERCE- Framework, Technologies and Applications © Tata McGraw-Hill 4 World Wide Web: URL Uniform Resource Locator – specifies uniquely each publicly available document on the Internet. Uniform Resource Locator – specifies uniquely each publicly available document on the Internet. URL Consists of three parts- URL Consists of three parts- –First component specifies protocol { delimited by // ) –Second component domain name of the machine (between // and /) –Last component the file/document name ( from / till : or End of string) Examples Examples – Protocol name- http Protocol name- http Domain/Machine name- icrc.iiml.ac.in Domain/Machine name- icrc.iiml.ac.in File name- index.htm File name- index.htm

ELECTRONIC COMMERCE- Framework, Technologies and Applications © Tata McGraw-Hill 5 World Wide Web: HTTP Hyper Text Transfer Protocol A set of rules that World Wide Web Clients and Servers use for communicating with each other A set of rules that World Wide Web Clients and Servers use for communicating with each other It is a connection less protocol It is a connection less protocol Client contacts a server, opens a connection and submits request. The server processes and responds to the request and closes connection. Client contacts a server, opens a connection and submits request. The server processes and responds to the request and closes connection. Each request is treated as independent of previous requests. It is a state-less protocol Each request is treated as independent of previous requests. It is a state-less protocol The protocol has three commonly used request methods – Get, Head and Post The protocol has three commonly used request methods – Get, Head and Post

ELECTRONIC COMMERCE- Framework, Technologies and Applications © Tata McGraw-Hill 6 HTTP: Client Server Interaction

ELECTRONIC COMMERCE- Framework, Technologies and Applications © Tata McGraw-Hill 7 HTTP: Get and Post Headers Get Request Header Get Request Header GET / HTTP/1.1 User-Agent:Mozilla/4.75 Referer: Accept:image/gig, image/jpeg, image/png, */* Accept-Language:en Accept-Charset:utf-8, iso Post Request Header Post Request Header POST/myprog.cgiHTTP/1.1 User-Agent:Mozilla/4.75 Referer: Accept:image/gig, image/jpeg, image/png, */* Accept-Language:en Accept-Charset:utf-8, iso Content-type:application/x-www-form-urlencoded Content-length: Carriage Return username=myuserid&name=G+I+JOE

ELECTRONIC COMMERCE- Framework, Technologies and Applications © Tata McGraw-Hill 8 World Wide Web Servers CERN HTTPd CERN HTTPd NCSA HTTPd NCSA HTTPd Apache HTTPd Apache HTTPd Today Web server provide following four functions Today Web server provide following four functions –Serving the static web pages –Serving the web pages generated by running gateway programs –Controlling the access to the server –Logging server access and error statistics