Scripting LanguagesDiane Krebs

11-7-14

Overview

How it works

What are scripts

Different Scripting Languages

Web pages & scripts

Conclusion

:Web

Browser

Web

Server

1 - Request an HTML Page

4 - Present HTML Content

2 - Retrieve requested HTML

3 - Return HTML to Browser

HTML

How it Works

I n t e r n e t

Client requests page

Completed HTML sent to client

Web Server

Client Machine With Web Browser

• The script, written by the website developer, generates the HTML code of the page requested.

• The HTML code is not actually a file. The code is actually held in the server’s memory until it is sent directly to the client.

• A script may run other scripts, depending on its function. It will however still only give one end result.

• A website does not have to be completely made up of either scripts or HTML files. It can use a combination of the two.

Script builds

HTML code

HTML ready to send

Server runs script

[ ASP / PHP / Ruby ]Script

HTML Code

How Scripting Languages Work

What Are Scripts?

A new style of programming language different from system programming languages

It does not matter what scripting language a website uses because there are no compatibility issues with clients’ web browsers.

Designed as glue language or system integration language

A single statement can execute huge number of machine instructions

Can create dynamic web pages

Change based on user input

The client only ever sees the final HTML generated by the script and not the script itself.

Scripts often finish running in several milliseconds. Most web servers can run many scripts simultaneously with a minimal performance hit.

Two Types

Server-side Scripting Language

Can use huge resources of the server

Complete all processing in the server and send plain pages to the client

Reduces client-side computation overhead

Client-side Scripting Language

Does not involve server processing

Complete application is downloaded to the client browser

Client browser executes it locally

Are normally used to add functionality to web pages e.g. different menu styles, graphic displays or dynamic advertisements

I n t e r n e t

1. Client requests page

2. Web server sends the HTML file to the client

Web ServerClient Machine

With Web Browser

• A simple website is made up of one or more static HTML files. This means the page

content does not change.

• The only way to update a page is for the author to edit the file.

• This is fine for small websites or those that require little updating.

• Static pages will not work for websites that need to deliver lots of custom and up-to-

date content: e-commerce, auctions, blogs, search engines, online banking

Static Web Pages

• The facebook homepage could be considered static because it has a fixed layout and content. It does not change.

• After Login results page however is dynamic. This means its content can be changed.

• The only practical way to create this page is by using a script

• The user never sees the work a script does, only the end result it sends back to their browser.

Dynam

ic W

ebPage

Sta

tic W

ebPage

Dynamic Web Pages

Perl, Python, Ruby Perl

Found on all Windows and Linux servers

Can handle text manipulation tasks

Excellent web scripting language

high-traffic websites that use Perl extensively

include Priceline.com, Craigs List, IMDB

Python

Can be used as a script or a programming language

OOP language with a lot of features which support of web applications as well as software programs

Industrial Light & Magic: "The Phantom Menace", "The Mummy Returns"

Walt Disney Feature Animation: uses scripts in their animation production system.

Shopzilla: configuration management and deployment, automated testing and internal tool development.

Perl Python, Ruby

Ruby

Various blogs, data processing applications

Twitter, Shopify, Groupon, HUlu

Ruby, Perl, Python, etc., are all open source

Rely on volunteers to

Write documentation

Write test cases

Maintain the systems

Port to new platforms

Fix bugs

Implement libraries

Implement new features

ASP-PHP

Active Server Pages (ASP)

Server side scripting language

Developed by Microsoft

Good at connecting to Microsoft databases

Runs only on Microsoft servers

Microsoft.com, GoDaddy, Skype, NYTimes.com

PHP (Hypertext Pre-Processor)

Especially good at connecting to MySQL

Generate Dynamic content and good User Interface

Server side execution

Facebook, Wikipedia, Yahoo, Photo-bucket, &

WordPress

JavaScript

JavaScript

Java and JavaScript are two completely different languages in both concept and design

Client-side & server-side scripting language

Enhance dynamics and interactive features of a web page

Allows one to perform calculations, write interactive games, add special effects, customize graphic selections, create security passwords

used in millions of web pages

to improve the design

to validate forms

to detect browsers

to create cookies

JavaScript and HTML page

<html>

<body>

<script type=“text/javascript”>

document.write(“Hello World!”);

</script>

</body>

</html>

This code produce the output on an HTML page:Hello World!

Tells where the JavaScript ends

Tells where the JavaScript starts

Commands for writing output to a page

Conclusion

Scripting languages make the web development work

Easier

Faster

Best utilization of resources

http://www.w3schools.com/html/html_scripts.asp

Questions