Web Application Development

DINESH KUMAR RAMPGT(COMPUTER SCIENCE)

KENDRIYA VIDYALAYA NAD, ALUVA

INTRODUCTION TO WEB

APPLICATION

WEB APPLICATION

A web application is an application that is accessed over a network such as the Internet or an intranet. The term may also mean a computer software application that is hosted in a browser-controlled environment (e.g. a Java applet) or coded in a browser-supported language (such as JavaScript, combined with a browser-rendered markup language like HTML) and reliant on a common web browser to render the application executable.

WEB BROWSER

A Web Browser is aWWW client that

navigates through the World Wide Web and displays web pages.

e.g. Internet Explorer,

Mozilla firefox, Netscape Navigator etc

WEB SERVER

A WEB SERVER is a WWW server that stores web documents and responds to the request made by web browsers.

e.g. Apache HTTP Server, Internet Information Services(IIS) , Sun Java System Web Server, Jigsaw Server

Function of Web ServerThe primary function of a web server is to deliver web pages to clients. This means delivery of HTML documents and any additional content that may be included by a document, such as images, style sheets and JavaScripts.

Running gateways programs and returning output

Controlling access to the server

Monitoring and logging server access statistics

Web Address and URLWeb Address : In computing, a Uniform Resource Locator (URL) is a subset of the Uniform Resource Identifier (URI) that specifies where an identified resource is available and the mechanism for retrieving it.

HTTP USES INTERNET ADDRESSES IN A SPECIAL FORMAT CALLED A UNIFORM RESOURCE LOCATOR OR URL.

e.g. http://kvnadaluva.gov.in

http://cbse.nic.in

Syntax Elements of URL’s

Communicating with Web Server

Client Server Communication

• Client Server computing refers to a network set-up in which programs and information reside on the server and clients connect to the server for network access.

Computers: Clients and ServersIn a client/server network arrangement, network services are located in a dedicated computer whose only function is to respond to the requests of clients.

The server contains the file, print, application, security, and other services in a central computer that is continuously available to respond to client requests.

Networking Protocol: TCP/IP

Web Protocols

HTTP (Hyper Text Transfer Protocol ) used on the World Wide Web (WWW) for transferring web pages and files contained in web pages such as images.

FTP (File Transfer Protocol) employed for transferring files from one machine to the other.

SMTP (Simple Transfer Protocol) used for E-Mail.

Telnet Protocol used to open remote-machine access (telnet session)

Clients Server Communication Model

The client server communication over the web can

take places in two forms :

For accessing static HTML pages

For accessing dynamic web pages

Client Server CommunicationStatic HTML pages

Client Server CommunicationDynamic web pages

• Dynamic Web pages are generated via

two different technologies :

CGI ScriptsServer side Scripts

Client Server Communication with CGI Script

Client Server Communication with Server Side Scripting