1. Web Technology
Dr. M. Durairaj, Ph.D.

2. Web Technology
Web technology refers to the means by which computers communicate with each other using markup languages and multimedia packages.
It gives us a way to interact with hosted information, like websites.
Web technology involves the use of hypertext markup language (HTML) and cascading style sheets (CSS).

3. History of Internet and World Wide Web
Introduction
More than two billion Internet users
30% of the earth’s population
Billion general-purpose computers
Billions or more embedded computers, cell phones, smartphones, home appliances and automobiles and more.
We learn the technology which is portable.

4. Client-side programming technologies
HyperText Markup Language 5 (HTML5)
Cascading Style Sheets (CSS3)
Powerful, dynamic, fun features, audio, video, animation, drawings and effects….
Java Script – the language for client side
jQuery – the JavaScript Library
Ajax (Asynchronous JavaScript And XML) development, better performing, usable applications.

5. Servier-Side programming
The applications that respond to requests from client-side
Searching, browsing, checking bank-account, ordering in amazon, bidding in eBay, ordering tickets, etc.
PHP, ASP.NET (both C# and VB), JavaServer Faces
Moore’s Law – (Inter Chief Gorden Moore) Every year cost of product escalates, but computer h/w cost reduces.

6. The Internet in Industry and Research
Technology companies, such as Apple, IBM, etc. recruits more peoples.
Most computer applications run which are not connected to other computers.
Internet applications used in research & industry.
E.g.
Electronic health records, Human Genome Project
AMBER Alert – America’s Missing: Broadcast Emergency Response
World Community Grid – people can donate their unused computers
One Laptop Per Child – provides low power inexpensive labtops.
Cloud Computing – Amazon S3, EC2, Azure, etc.
GPS – Global Positioning System,
Robots – NASA’s Mars rover, military combat, deep sea and space exploration.
, Instant Messaging, Video chat and FTP

7. HTML5, CSS3, JavaScript, Canvas and jQuery
Client side web applications
HTML5 – markup languages for content and structure of web pages.
Extraordinary range of devices: Smartphones, tablet computers, notebooks, desktops, special purpose devices
Creating table, headers, navigation areas, footers, sections, figures, captions, etc.
XHTML (Extensible Hyper Text Markup Language) based on XML (eXtensible Markup Language)
CSS – Cascading Style Sheets
Provides capabilities to control document’s presentation – font, spaces, sizes, color, positioning, etc)

8. JavaScript
Build dynamic web pages ( can be modified on the fly)
Created by Netscape
Standardized by ECMA (European Computer Manufacturers Association)
jQuery
Popular of hundred of JavaScripts libraries

9. Evolution of the Internet and WWW
Late 1960s – ARPA (the Advanced Research Project Agency)
Networking of computers has bps
At that time 110 bps through telephone
Eventually ARPANET – evolved into today’s internet.
Packet Switching
Primary goal of ARPANET was to allow multiple user to send and receive simultaneously
Packet contains address, error-control and sequencing information
TCP/IP (Transmission Control Protocol / Internet Protocol) by ARPA
IP – truly a network of networks, current versions Ipv4 and next generation IPv6.

10. World Wide Web, HTML, HTTP
Explosive Growth
World Wide Web, HTML, HTTP
1989, Tim Berners-Lee of CERN (European Organization for Nuclear Research) developed a technology for sharing info. via hyperlinked
HTTP – he wrote protocol – communications protocol used to send information over the web.
HTTPS – secure the information
Mosaic, Netscape, Emergence of Web 2.0
1993 – Mosaic browser – user friendly graphical interface
Google’s Web 2.0 – YouTube (video sharing), Facebook (social networking), Twitter (microblogging), Groupon (social commerce), Foursquare (mobile check-in), Skype (Internet telephony), Wikipedia (online encyclopedia)

11. Web Basics Web page – HTML Hyperlinks
URIs (Uniform Resource Identifiers) and URLs (Uniform Resource Locators)
Web Servers – make available of resources.
Apache’s HTTP server, MS IIS
DNS – Domain Name System- maintains the hostnames and corresponding IP addresses

12. Making a Request and Receiving a Response

13. HTTP Headers
Provides additional information about the data that will be sent.
Content-type: text/html
MIME – Multipurpose Internet Mail Extensions
Type of content that server sends
HTTP get and post Requests
Two request methods, get and post
Client-Side Caching (save on disk)

14. Data Hierarchy
Data hierarchy becomes larges and more complex

15. Levels of the data hierarchy
Bits – smallest data item – value 0 and 1
Characters – decimal (0-9), letters, Special symbols
Fields – composed of bits – characters, bytes
Records- several related fields
Files – group of related records

16. Operating Systems
OS are s/w that make using computes more convenient for users, developers, admins
Allows concurrent
Windows 10, Mac OS, Unix, Linux, Sun OS, Android, IOS, etc.
Desktop and Notebook OS:
Mobile OS – iOS for iPhone, iPad and iPod for Touch, Android
Types of Programming Languages
Instructions which computers understand
High level – Machine level (conversion by translators)
C, C++, Object-C, Visual Basic, Visual C#, Java, etc.
PHP, Python, JavaScript, Ruby on Rails, Scala

17. Object Technology
Aim: Building s/w quickly, correctly and economically.
Objects – more precisely the class – comes from a reusable s/w components.
Attributes (name, color, size)
Behaviors (calculating, moving, communicating)
Object
E.g. Automobile as an Object
Methods and Classes
– bank deposit, withdraw, inquire (a method)
Instantiation
Build a car before driving
Reuse
Can be reused many times to build many cars

18. Messages and Method Calls Attributes and Instance Variables
Car pedal sends message to cars
Attributes and Instance Variables
Car has attributes (color, no in door),
Every car maintains its own attributes
Encapsulation
Classes encapsulate (wrap) attributes and methods into objects – information hiding
Inheritance
New class of objects can be created quickly and conveniently by inheritance
New class observes characteristics from existing class

19. End of Unit – I Thank you