Web Tech Class 1

8/8/2019 Web Tech Class 1

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Mr. Debojit Boro

Assistant Professor,Tezpur University,Napaam,Tezpur-784028

Web Technology

Batches:

M.Tech. 2nd Semester

B.Tech 6th Semester

MCA 4th Semester

Class No. 1


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Topics for today

Basics of Internet

Mr. Debojit Boro



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What is Internet?

Worldwide system of computer networks-network ofnetworks

Connected by the telecommunication lines like fibreoptics and broadband

No ownership, accessible and modifiable

Mr. Debojit BoroAssistant Professor,Tezpur University,Napaam,Tezpur-784028


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History of Internet

Birth of Internet

Funded by the US government to Advanced Research

Projects Agency (ARPA) in 1957

1969-ARPA established ARPANET, the forerunner of Internet

ARPANET used by only Scientist, Researcher and Military

Connected to only major computers in University of California

at Los Angeles, the University of California at Santa Barbara,

Stanford Research Institute, and the University of Utah

Mr. Debojit Boro



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Limitations of Internet

Textual Based

Used command lines computer interaction

Not Graphical User Friendly

World Wide Web inspired by the Internet

Mr. Debojit Boro



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Birth of the

World

Wide

Web

In 1991 by developer Tim Berners-Lee and others at theEuropean Laboratory for Particle Physics, also known as ConseilEuropean pour la Recherche Nucleure(CERN)

Protocol based on Hypertext in

Web

Web browsing software

Internet limited to noncommercial users as its backbone wasprovided by NSF,NASA and US DoE and funded by US

government. 1992, Delphi provided full access

June 1993, Web boasted just 130 web sites and by 1998, thenumber to rose to more than 2.2 million


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But what is Hypertext

?

Text that contains links to other text

URLs and Domains


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The Anatomy of URL

A URL signifies the full,unique path of any file in the Internet.

For e.g. http://www.yahoo.com/index

Or www.yahoo.com/index

http://www.yahoo.com/index

Protocol to be used Domain Name Document/file name


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Web Browser working Mechanism

Web Browser Web Serverat yahoo.com

Internet

Index File

2. Web Server sends thefile www.yahoo.com/index

1. Web Browser

requests for the file

www.yahoo.com/index

3. Web Browser

interprets the

file and displaysits content on

screen

Interaction between a Web Browser and a Web Server


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Working steps of

Web Browser

1. User types the full file name

2. The Browser requests DNS for the IP address correspondingto www.yahoo.com/index

3.DNS replies with the IP address eg 120.10.23.21

4. Browser makes a TCP connection with the server

5. The client makes a explicit HTTP request for the Web Pageto the Web Server using HTTP

GET

HTTP

HOST

GET/ index/htm

HOST: yahoo.com


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The request is handed over to the HTTP software running onclient machine

HTTP software (HTTP request) - > TCP/IP software

TCP/IP software breaks the HTTP requests into packets and

sends to the Web server TCP/IP software in the Web server reassembles packets

TCP/IP software (HTTP request) - > HTTP software

HTTP software in the server interprets HTTP requests

OS retrieves the file index.htm and gives to HTTP software

HTTP software forms HTTP response by adding some headers HTTP software (HTTP response) - > TCP/IP software

TCP/IP software breaks HTTP response into packets

TCP/IP software on client reassembles those packets


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TCP/IP software in the client informs the HTTP software in theserver that the Web Page has been received correctly

Knowing this, HTTP software terminates the TCP connection

HTTP -> Stateless protocol

*TCP connection is opened for every page

TCP/IP software in the client hands over the web page to the Web

Browser


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HTTP commands

HTTP Command Description

GET Request for obtaining aW

eb PageHEAD Request to read the header of a Web Page

PUT Request the server to store a Web Page

POST Similar to PUT, but is used for updating a Web Page

DELETE Remove a Web Page

LINK Connect to resources

UNLINK Disconnect two resources


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IP Addresses Why the IP address are needed?

Network 1 Network 2A

A in Network 1: 160.80.40.20

A in Network 2: 162.81.40.20


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Classes of IP Address

0 Network Host Number

1 0 Network Number Host Number

1 1 0 Network Number Host Number

1 1 1 0 Multicast Address

1 1 1 1 0 Reserved for future use

A

B

C

D

E

Byte 1 Byte 2 Byte 3 Byte 4


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How to identify the class,network number and the host

number?

Eg. IP address 160.80.40.20

In bits

10100000 01010000 00101000 00010100

160 80 40 20


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Result: 8272 (nn)

10260(hn)

Documents

Web Tech Class 1