Web Applications

Evolution of Applications and Web….

Agenda

Importance of Web in Industry

Evolution of Applications

Evolution of Web

Web Applications

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What's the Buzz!

Is it really a Buzz?

Web market is huge and everyone wants its share

Applications are changing

Operating Systems are changing…

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Industries are changing…

Web is reaching Devices

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Why a shift to web?

Applications and Web Applications

Some Applications…

Some web pages…

Application and Web Page

Application

Standalone

Performs some functionality

Installed binaries

Highly interactive

Web Page

Run in Applications (Browser)

Displays information

Temporary content

Less interactive

Application or Web Page

Web Page

Not installed

Launched in Browser

Application

Allows Chat

Audio, video enabled

Not just displays data

?

Web Applications

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Web applications

Applications in the browser

Applications, but not installed

Web pages highly interactive

There are 2 type of Websites

• That display some stuff like magazines (webpages)

• That allow to perform some stuff like softwares (web applications)

Application challenges

- Portability

- Extensibility

- Updating

- Easy deployment

What are the options to implement an application?

C/ C++ exe

C/ C++ library (static/ dynamic)

Java classes

Scripting languages (perl, pyhthon, javascript)

Implementing as Web application

Deployment

Just a URL http://www.mathfunctions.com/factorial&n=5

Portability

NO OS/ programming language dependency

Extensibility

Can be used in numerous applications without changing the server module

Updating

Any changes in server side doesn’t affect client implementations

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Evolution of Applications

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Evolution of Computers

Computers came into existence

They made user’s life easier

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But life of developer was hard

Programming languages were highly dependent on hardware

For same application, code had to be re-written for another hardware!!

Evolution of Operating Systems

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Operating System

HW HW HWHW

Code Code CodeCode

One Hardware

The Hardware

specific Code

New Hardware

RewriteCode

Code

SingleCode for all Hardware !!

Hence the Applications

Applications are compiled to Native Binaries (executables)

Technologies

C

C++

Pros

Can directly access system level APIs

Fast in execution

Cons

To maintain different application binaries for different operating systems

Big development effort required

Evolution of Virtual machines

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Virtual Machine

OS OS OSOS

Code Code CodeCode

One OS

The OS specific

Code

New OS

RewriteCode

Code

SingleCode for all

OS !!

Applications compiled for Virtual Machines

Technologies

Java (J2SE)

.NET

Action Script (Flex)

Scripting languages

Perl, Pyhton, PHP etc.

Pros

Single application for different OS hence easier to maintain

Less development effort

Cons

Target OS must have the virtual machine installed in order to execute the application

Slow in execution as compared to Native OS Applications

Don’t have access to system level APIs

Evolution of WEB

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Web/ Internet

DARPA/ ARPA (Advanced Research Projects Agency)

Defense programs during the cold war era

Goal: Command and control network that would survive a nuclear war

Problems: Circuit switch networks (e.g. Telephone) are vulnerable as loss of line or a switch may hamper the communication

Solution: Distributed, packet switched networks

The number of machines, networks and users increased dramatically after the advent of TCP/ IP- the Internet

TCP/IP Reference model and the protocol is the glue that holds internet together

Growth of universal services on top of TCP/IP infrastructure (Application layer)

E-mail

File transfer

Remote login

World Wide Web (WWW)

Basic Web system

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Basic Web System - example

Google Web Server

Browser requests a web page from www.google.com

Generates an HTML and sends it as

response

HTTP Basics

HTTP Client HTTP Server

HTTP Request

HTTP Response

• Every HTTP Request can be of following predefined HTTP methods• GET – download a resource• HEAD – retrieve header information of a resource• PUT – upload a resource to the server• POST – submit data to be appended to a resource• DELETE – delete a resource

• HTTP protocol consists of 2 distinct items• HTTP Request – what the user wants to do• HTTP Response – output of the request

Web (Till mid 90s)

Features

Page metaphor

Synchronous

Smaller set of UI controls

Mostly text oriented

One way traffic, not participative

Lacked

Rich Content

Images

Audio

Video

Interactivity

Page Metaphor and synchronous web

A new HTML page is loaded on every request, like searching something on google.com

Which means entire content reloaded on every HTTP request.

Issues

Most of the times, entire content need not to be updated in the web page

Slows down the work speed

Looks irritating

So people felt need of Asynchronous Web!!

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Technologies

Client Side

HTML – a mark up language rendered by Browsers

Java Script – to put some logic in web pages executed by Browsers

Server Side Scripts (executed by a web server)

ASP/ ASP .NET

PHP

Coldfusion

Java via JSP

Perl

Pyhton

Ruby

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Asynchronous Web

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Allowed websites to update data without fetching entire web page.

Impact

• Allowed fast user interactivity with web pages

• Users turned into publishers

• Personal web sites were replaced by blogs

• Birth of wikis

• Social networking websites came into existence

• User participations on web reached billion benchmark

• Web giant innovated monetizing techniques for web

• Web advertisements market

Technologies

Java Applets (1995)

Allow compiled client-side code to load data asynchronously from the web server

Required JVM to ne installed at client machines

XMLHTTPRequest (1999)

Fetches XML data asynchronously from web

Invoked from java script

Core component of AJAX

Became widely known after used by Google in Gmail(2004) and Google maps(2005)

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AJAX – Asynchronous JavaScript & XML (2005)

Only a name given to a set of tools that were already existing

HTML and CSS for presenting

Java script for local processing (client side functionality)

XMLHTTPREquest object – used to send or receive data from server asynchronously

Accepted as an official web standard in 2006 by W3C.

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Traditional Web system vs AJAX based Web system

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Traditional Web system vs AJAX based Web system

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Thank You

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