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History of Internet

1950s and early 1960s

Communication between stations on the samenetwork

Terminals connecting to central mainframe via long

leased lines

Problem of connecting disparate type ofnetworks

Need for Inter-networking

Solved by Packet switching

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Transition Towards Internet

TCP/IP (late 1970s)

Term Internet first used

Several Wide Area Networks based on TCP/IP

NSN, CSNet, ESNet

CSN

et connected with ARPAN

et (1984) Term internet came intro general use

TCP/IP became worldwide

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World Wide Web

Need to uniformly access wide array of

information Gopher, WAIS etc.

Tim-Berners Lee at CERN created WWW in1989 based on hypertext

A seamless world in which all information, fromany source, can be accessed in a consistent andsimple way

Mosaic Web Browser & httpd Web Server

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Model of WWW and HTTP

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client server

request

response

Client Machine Host or Server Machine

Governed by Communication

Protocols

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Static Content

Mosaic could fetch and view static documents

and images served by the httpd server A static document is one that exists in a constant

state, such as a text file that doesn't change

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Need for Dynamic Content

Glut of online resources soon made search

engines necessary Process the data and provide appropriate content

Extension of Web Servers by modifying the

source code (impractical)

NCSA developed the Common Gateway

Interface (CGI) specification

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Server Side Technologies

PERL Scripts to execute CGI Programs

PHP (1995): Platform Independent Initially as a set of PERL scripts and later C

implementation to replace PERL scripts

ASP (1996): Platform dependent

Integrated application execution directly into theweb server

Java Servlets (1997) Platform Independent Server side Java Programs to extends web servers

functionality

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Server Side Technologies

Java Server Pages

Extension of Java Servlets

Cold Fusion (1995)

Initially Visual C++ based

J2EE based

ASP.NET (2002)

Extension of ASP to .NET framework

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Software Applications

A Software application can be broadly divided

into three layers User-interface (Presentation)

Business Logic

Database

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Applying Software Application Architecture over Web

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Web Application Architectures

3-Tier Architecture

N-Tier Architecture

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Examples of Web Applications

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All kinds of business applications based on the model of web