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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
Assistant Professor,Tezpur University,Napaam,Tezpur-784028
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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
Assistant Professor,Tezpur University,Napaam,Tezpur-784028
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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
Assistant Professor,Tezpur University,Napaam,Tezpur-784028
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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)