Module 1

Introduction to Web Technology

Objectives:
● To get familiar with the basics of Internet Programming
● To understand the basic network concepts.
● To acquire knowledge and skills for creation of web site considering both client and
server side programming.
● To gain ability to develop responsive web applications and explore different web
extensions and web services standards.
● To learn characteristics of RIA and React Js
Outcome:
● Implement interactive web pages using HTML and CSS
● Design a responsive web site using JavaScript and demonstrate database connectivity
using JDBS
● Demonstrate Rich Internet Application using Ajax and demonstrate and differentiate
various web extensions.
● Demonstrate web application using Reactive Js
What is Web Technology?
● Web technology refers to the means by which computers communicate with each
other using markup languages and multimedia software packages.
● It gives us a way to interact with hosted information, such as websites.
● It involves the use of Hypertext Markup Language (HTML) and Cascading Style
Sheets (CSS).
● The three basic languages that make up the World Wide Web are HTML, CSS, and
JavaScript.
Web Essentials:
Server: The software that distributes the information and the machine where the information and software reside
is called the server.

• provides requested service to client

• e.g., Web server sends requested Web page

Client: The software that resides on the remote machine, communicates with the server, fetches the information,
processes it, and then displays it on the remote machine is called the client.

• initiates contact with server (“speaks first”)

• typically requests service from server

• Web: client implemented in browser

Client-Server Paradigm
● Client process running on
client host
● Server process running on
server host
● Communication
established via request
response protocol
● Central Repository of
Information
Web Essentials:
Web server: Software that delivers Web pages and other documents to browsers using the HTTP
protocol

Web Page: A web page is a document or resource of information that is suitable for the World Wide
Web and can be accessed through a web browser.

Website: A collection of pages on the World Wide Web that are accessible from the same URL and
typically residing on the same server.

URL: Uniform Resource Locator, the unique address which identifies a resource on the Internet for
routing purposes.
The Internet:
• Medium for communication and interaction in inter connected network.

• Makes information constantly and instantly available to anyone with a connection.

Web Browsers:

• User agent for Web is called a browser: Internet Explorer, Firefox

Web Server:

• Server for Web is called Web server: Apache (public domain)

MS Internet Information Server
Basic Internet Protocols:
● Protocols are agreed formats for transmitting data between devices. The protocol determines:

i. The error checking required

ii. Data compression method used

iii. The way the end of a message is signaled

iv. The way the device indicates that it has received the message

● There are many protocols used by the Internet and the WWW:
○ TCP/IP
○ HTTP
○ FTP
○ Electronic mail protocols IMAP
○ POP
 TCP/IP
● Internet protocol (IP):
○ IP delivers (routes and addresses) data packets between a source
(device or application) and their destination.
○ It makes sure that those packets arrive at the right destination.
○ It defines the rules and formats for applications and devices to
communicate and exchange those data packets on a specific network or
across different connected networks.
● Transmission control protocol (TCP):
○ TCP organizes data in a specific manner to protect them while
exchanged between a client and a server.
○ It’s a very used protocol on networks by all types of devices and
applications.
○ TCP protects data’s integrity from the sending and all the way to their
delivery.
Hypertext Transfer Protocol (HTTP)
● HTTP was designed to transfer pages between
machines
● The client (or Web browser) makes a request for a
given page and the Server is responsible for finding
it and returning it to the client
● The browser connects and requests a page from the
server
● The server reads the page from the file system,
sends it to the client and terminates the connection.
Electronic Mail Protocols:
● Electronic mail uses the client/server model
● The organisation has an email server devoted to handling email -Stores and forwards email messages
● Individuals use email client software to read and send email

o (e.g. Microsoft Outlook, or Netscape Messenger)

● Simple Mail Transfer Protocol (SMTP)

o Specifies format of mail messages

● Post Office Protocol (POP) tells the email server to:

o Send mail to the user’s computer and delete it from the server

o Send mail to the user’s computer and do not delete it from the server o Ask whether
new mail has arrived.
● Internet Mail Access protocol(IMAP):
○ This protocol is used while receiving an email.
○ When one uses IMAP, the emails will be present in the server and not get downloaded to
the user’s mail box and deleted from the server. This helps to have less memory used in
the local computer and server memory is increased.
World Wide Web(WWW)
● The internet came first. Internet and WWW are two different concepts.
● Internet- It is a global computer network made up of thousand of computers &
computer network.
● WWW- It is a system that interlinked via Internet.
Difference between Internet and WWW
1) Internet- is a global system of interconnected computer network. This computers communicate
with each other using a common protocol (TCP/IP i.e. Transmission Control Protocol / Internet
protocol )
World Wide Web (WWW) : It is one of the services that run on internet. WWW is a system of
interlinked hypertext documents accessed via Internet. Way of accessing the information
2) The Internet and the Web are two separate but related things.
Internet – It is a massive network of networks. It connects millions of computers together
globally, forming a network in which any computer can communicate with any other computer as
long as they are both connected to the Internet.
WWW- The World Wide Web, or simply Web, is a way of accessing information over the
medium of the Internet. So the Web is just a portion of the Internet
 HTTP Message
HTTP message is the information transaction between the client and server.

Two types of HTTP Message

1. Requests
a. Client to server
2. Responses
a. Server to client
Fields

· Request line or Response line

· General header

· Request header or Response header

· Entity header

· Entity body
Request Message:
● A request line has three parts, separated by spaces
○ a method name
○ the local path of the requested resource
○ the version of HTTP being used

● A typical request line is: GET /path/to/file/index.html HTTP/1.1

○ GET is the most common HTTP method; it says "give me this resource". Method names are always
uppercase
○ The path is the part of the URL after the host name, also called the request URI o The HTTP version
always takes the form "HTTP/x.x", uppercase.
Request Header
Response Message:
● A request line has three parts, separated by spaces
○ the HTTP version,
○ a response status code that gives the result of the request, and
○ an English reason phrase describing the status code
● Typical status lines are:
○ HTTP/1.0 200 OK or
○ HTTP/1.0 404 Not Found
HTTP Response Header: