This document provides a high-level overview of key web concepts: - It describes common web protocols like HTTP and HTTPS, and models including TCP/IP and OSI. - Infrastructure components are explained such as servers, databases, load balancers and caching. - Web technologies are defined including HTML, CSS, JavaScript, images, XML and JSON. - Additional topics covered are cookies, forms, responsive design, AJAX, and comparisons of HTML5 vs Flash.

1. Fundamentals of WebHigh level overview of web concepts
Lemİ Orhan Ergİn
Principal software Engineer @ Sony
guide for non-developers

2. The aim of this training is to let you
•know concepts of web and web applications
•understand how web based software works
•understand the technical discussions better
•and answer your questions:)

3. agenda
•Web Concepts
Http/Https, Cookies, Caches, Forms, Html, Javascript, CSS, Request/
Response, Responsive Web Design
•Infrastructure
Servers, Databases, Load Balancers

4. web concepts

5. The Internet is a global system of interconnected
computer networks
www, email, social networking, file transfer, online
chat, commerce, game playing, teleconferencing,
VoIP, video on demand etc.
Internet is tangible network of computers
sharing/exchanging information with the help of
PROTOCOLS.
Internet

6. Protocol
Protocol is a form of etiquette.
Internet Protocols are the standards, designed to
specify how computers interact and exchange
messages over internet.
Protocols usually specifies:
The format of the messages &
how to handle errors

7. Open systems ınter-connection (OSI) model
is a conceptual model that describes the internal
architecture of a communications system by splitting
its components into abstraction layers.

8. tcp model
This model is a condensed version of the OSI model
and only has four layers. It is considered as standard
around internet.

9. http model
It stands for HypertextTransfer Protocol.
HTTP provides a set of rules and standards that
govern how information is transmitted on the World
Wide Web.
http://www.sony.co.uk

10. http model
HTTP is a client-server protocol by which two
machines communicate using a reliable, connection-
oriented transport service such as theTCP.
Opens a tcp/ip connection via sockets
Transmits the request for a document
Waits for a reply from the server
Once the response is arrived, the socket is closed
Request
Response

11. http model
There is no memory between client connections.
Pure HTTP server treats every request as if it was
brand-new (i.e. Stateless)
To load faster, Http pages are stored in your
computer and internet caches.You don’t have control
over some caches like the ones in proxies.

12. PORT NUMBERS
A port is an endpoint to a logical connection and the
way a client program specifies a specific server
program on a computer in a network
Port numbers range from 0 to 65536, but the first 1024 are reserved for privileged services.
The other ports could be used by any application.
HTTP: 80
SSH: 443
TELNET: 23

13. Privacy: Anyone can see the content
Integrity: Anyone can alter the content
Authentication: Authentication is sent in clear form
Stateless: Need to maintain information across
multiple request-responses
http Limitations

14. HTTPS stands for HypertextTransfer
Protocol over Secure Socket Layer, or
HTTP over SSL.
SSL acts like a sub layer under regular
HTTP application layering.
HTTPS encrypts an HTTP message
prior to transmission and decrypts a
message upon arrival.
httPS

15. HTTPS by default uses port 443 as opposed to the standard HTTP
port of 80.
URL's beginning with HTTPS indicate that the connection between
client and browser is encrypted using SSL
SSL transactions are negotiated by means of a key based encryption
algorithm between the client and the server, this key is usually either
40 or 128 bits in strength (the higher the number of bits the more
secure the transaction).
httPS
https://login.yahoo.com/config/login_verify?src=ym

16. SSL HANDSHAKE

17. HTTP server is implemented by servers
Each client-server transaction consists of 3 main parts:
1) Request/Response line 2) Header information 3)The body
http model

18. there are several ways
to send a request
GET
POST
PUT
DELETE
HEAD
OPTIONS
TRACE
CONNECT

19. HTTP METHOD: GET
•Retrieval of information
•Server sends a representation of a resource to client

20. HTTP METHOD: POST
•The body of the request is accepted as a resource
•Mainly the data of forms are submitted by post

21. Web Content
Scripts (javascript)
Styles (css)
Pages (html)
Images (jpg, png, gif)
Web content is sent from server and browsers
renders and displays that is programmed.
Data* (xml, json)

22. Web Content: HTML
HyperText Markup Language (HTML) is the main
markup language for creating web pages and other
information that can be displayed in a web browser.

23. Web Content: Javascripts
JavaScript (JS) is an interpreted computer programming language. It was
originally implemented as part of web browsers so that client-side
scripts could interact with the user, control the browser, communicate
asynchronously, and alter the document content that was displayed.

24. Web Content: CSS
Cascading Style Sheets (CSS) is a style sheet language used for
describing the presentation semantics (the look and formatting) of a
document written in a markup language.

25. Web Content: IMAGES
Any image could be displayed in an html page. It is important to keep
the side of images small for the sake of performance.

26. Web Content: XML
Extensible Markup Language (XML) is a
markup language that defines a set of
rules for encoding documents in a
format that is both human-readable and
machine-readable.

27. Web Content: JSON
JavaScript Object Notation (JSON), is a
text-based open standard designed for
human-readable data interchange

28. Server
Browser
Infrastructure
Server infrastructure could be that simple!

29. Load Balancer
Web Servers
Load Balancer
Application Servers
Database Servers
Proxy
Browser
Servers in the
same zone does
not interact over
proxy
Zone
The content can
be cached in any
of the levels
Central Cache Servers
The infrastructure
could be simpler
than here
Server infrastructure
could be much more
complex too

30. Client
request - response
You request a web page and get data
Server
Client
Browser caches the content
ServerCache
200
Client
You request the same web page with
last modified date of the cached content
Server
304
Client
Since server says “content has not
changed”, the data in cache is loaded
ServerCache
1
2
3
4
Server does not return content. It just
returns status code 304
Server returns content with code 200

31. Caching
Any content can be cached in any infrastructural node
•Scripts (javascript)
•Styles (css)
•Pages (http pages)
•Images
•Animations (flash)

32. Load Balancer
Web Servers
Load Balancer
Application Servers
Database Servers
Proxy
Browser
Zone
Central Cache Servers
Returns cached scripts,
styles and content from
browser cacheRefresh By f5
Cache-­‐Control: no-­‐cache // HTTP 1.1
Pragma: no-­‐cache // HTTP 1.0
Expires: Sat, 26 Jul 1988 05:00:00 GMT // in past
Asks for content if cache is not set

33. Load Balancer
Web Servers
Load Balancer
Application Servers
Database Servers
Proxy
Browser
Zone
Central Cache Servers
Refresh By
CTRL+f5
Asks for content. Browser
cache is not used.

34. Load Balancer
Web Servers
Load Balancer
Application Servers
Database Servers
Proxy
Browser
Zone
Central Cache Servers
cache on
server side
Cache could be on server side
and needs to be cleaned either
automatic or manually

35. ajax
Acronym for Asynchronous JavaScript an XML
It is a web development technique used on the client
side to create asynchronous web applications.

36. ajax
Let’s see how ajax works. Fill the
following text area.

37. ajax
Write a text and press the button

38. ajax
Page is not refreshed.A new text
appears below the entry area.
Let’s look at how it works

39. ajax
Page is initially loaded to
your machine
Source code of the page
can be displayed within
browser

40. HTML Code
Document Object model
ajax

41. ajax
When you click on the
button, web page calls the
server from client site
(i.e. from your browser)Server
Browser

42. ajax
Server sends new data as response.The data
is put to object graph of the page at runtime.

43. ajax
Object graph is changed.The new data is
displayed on browser. But you cannot see the
new data in the source code of the page.
You can trace the response of server via
plugins like FireBug

44. Cookies
A cookie, also known as an HTTP cookie, web cookie,
or browser cookie, is a small piece of data sent from a
website and stored in a user's web browser while a user
is browsing a website.

45. Usage of Cookies
•Session Management
•Shopping Cart,Authentication
•Personalization
•Remember me, Preferences
•Tracking & Analytics
•Ads, Browsing History,Analytics,Tracking

46. Cookie Content
A web browser is expected to be able to store at least
300 cookies of 4 kb each, and at least 20 cookies per
server or domain.
•Cookie domain
•Path
•Expiration time or maximum age
•Secure flag
•HttpOnly flag.
•Name–value pair Data to send to server
Data to be used by browsers
to determine when to delete a
cookie, block a cookie or
accept a cookie

47. Setting Cookies
Cookies can not only be set by server. These can be set
by Javascript in client’s browsers (if cookie is not marked as HTTPOnly).

48. Forms
An HTML form on a web page allows a user to
enter data that is sent to a server for processing.

49. Forms
Forms can be generated in several ways
Server
Browser
Client Side
Server
Browser
Server Side
by programming languagesby javascript editing DOM

50. Form Validation
Forms can be validated in client side via javascript
and in server side by application.
Server Browser
Please note that validation on client
side could be bypassed easily

51. Responsive web design
Responsive web design (RWD) is a web
design approach aimed at crafting sites to provide
an optimal viewing experience—easy reading and
navigation with a minimum of resizing, panning, and
scrolling—across a wide range of devices (from
desktop computer monitors to mobile phones)
http://discover.store.sony.com/sportswalkman/
http://www.slideshare.net/bytte/responsive-web-design-10389263

52. HTML5 vs FLASH
Web browsers cannot render Flash media
themselves, instead it is rendered primarily using the
proprietary but freely available Adobe Flash Player
http://sixrevisions.com/html/html5-infographics/
http://venturebeat.com/2012/01/31/html5-versus-flash-infographic/
All web browsers support HTML and other Web
standards to various degrees.

53. HTML5 vs FLASH
It’s time for reading some code
http://charag.com/client/eagleriverdaycamp/v2/eagle.html
http://citwings.com/phillips_locked_room_game.html
HTML5 Animation
Flash Animation

54. References
http://www.slideshare.net/simplyharshad/http-vs-https
HTTP vs HTTPS

55. Lemİ orhan ergİn
lemiorhan@agilistanbul.com
@lemiorhan
@lemiorhan
agilistanbul.com
@lemiorhan
LINKEDINTWITTERSLIDESHAREBLOGGER
Principal Software Engineer @ Sony
Founder & Author @ agilistanbul.com