Introduction to Web Engineering & Web Engineering Protocols.

Introduction to Web Engineering & Web Engineering Protocols.

1. often just called the Web
World Wide Web (WWW)
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The World Wide Web is a collection of
web pages stored on web servers and
connected through hyperlinks.
It allows users to access, share, and
interact with information using the
Internet.
INVENTED BY: SIR TIM BERNERS-LEE
YEAR: 1989
AT: CERN (EUROPEAN ORGANIZATION
FOR NUCLEAR RESEARCH)
HE ALSO CREATED:
THE FIRST WEB BROWSER
(WORLDWIDEWEB, LATER CALLED
NEXUS)
THE FIRST WEB SERVER (CERN
HTTPD)
THE FIRST WEBSITE
(HTTP://INFO.CERN.CH/)
How the Web Works?
You enter a URL (Uniform Resource Locator) in a
browser (e.g., https://www.example.com).
The browser sends a request to a web server using
HTTP/HTTPS.
The server finds the webpage and sends it back to the
browser.
The browser renders the page using HTML, CSS, and
JavaScript.

2. Main Components of WWW
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Web Browser
Software to access and display web pages (e.g., Chrome, Firefox, Safari).
Web Server
Stores and delivers web pages to users.
Web Page
A document written in HTML that contains text, images, and links.
URL
Unique address used to access a web page.
HTTP/HTTPS
Protocols used for transferring web data securely.

3. Internet World Wide Web
A global network of computers.
A service that operates on top of the Internet.
Includes email, FTP, VoIP, etc. Only includes web pages and web services.
Hardware infrastructure. Software layer using the Internet.
Difference Between Internet and WWW
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4. Features of WWW.
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HYPERLINKED DOCUMENTS
GLOBAL ACCESSIBILITY
MULTIMEDIA INTEGRATION (TEXT, IMAGES, VIDEOS)
DYNAMIC CONTENT VIA SCRIPTING LANGUAGES
INTERACTIVE COMMUNICATION THROUGH WEB APPLICATIONS
Features of WWW.
SEARCHING ON GOOGLE
WATCHING VIDEOS ON YOUTUBE
ONLINE SHOPPING ON AMAZON
READING ARTICLES ON WIKIPEDIA
USING SOCIAL MEDIA PLATFORMS

5. Web Protocols
Web protocols are standard rules that define how data is transmitted and
communicated between web browsers, web servers, and other systems on the
World Wide Web (WWW).
They ensure that all devices on the Internet can understand each other and
exchange data reliably and securely.
HTTP (HyperText Transfer Protocol)
Full form: HyperText Transfer Protocol
Purpose: Transfers web pages from a web server to a browser.
Port: 80
Type: Application layer protocol
HTTPS (HyperText Transfer Protocol Secure)
Secure version of HTTP using SSL/TLS encryption.
Port: 443
Purpose: Ensures data security and privacy between browser and server.

6. FTP (File Transfer Protocol)
Purpose: Transfers files between client and server over the Internet.
Port: 21
Used for: Uploading website files to a web server.
Meaning of FTP Port 21
FTP (File Transfer Protocol) uses Port 21 as its default communication port to
transfer files between a client (your computer) and a server (web host or
remote system).
Role of Port 21
Port 21 is the command port used by FTP.
It handles the control connection, meaning it’s used for sending commands
and receiving responses between client and server.
Example:
The FTP client sends: USER
username
The server replies: 331
Password required
Then: PASS yourpassword

7. SMTP (Simple Mail Transfer Protocol)
Purpose: Sends emails between mail servers.
Port: 25 or 587
Used by: Email clients like Gmail, Outlook, and Yahoo Mail.
PORT 25 →
For mail servers to communicate
with each other.
PORT 587 →
For users and applications to send
emails securely to mail servers.
POP3 (Post Office Protocol v3)
Purpose: Receives emails from the mail server and downloads them to the
local device.
Port: 110
Note: Once downloaded, emails are removed from the server. Port 110 is the default port used by the POP3
(Post Office Protocol v3) — a standard protocol
for receiving emails from a mail server to a local
computer or device.

8. Feature POP3 (Port 110)
IMAP (Port
143/993)
Storage
Emails stored
locally
Emails stored on
server
Sync
No syncing across
devices
Syncs across all
devices
Offline Access Yes Partial
Best For
Single-device
users
Multi-device users
IMAP (Internet Message Access Protocol)
Purpose: Receives emails and keeps them stored on the server.
Port: 143 or 993 (secure)
Benefit: You can access your emails from multiple devices.
It allows you to read, manage, and organize your emails while
they remain on the mail server — instead of downloading them
permanently to your device.

9. DNS (Domain Name System)
Purpose: Converts domain names (like www.google.com) into IP addresses
(like 142.250.190.78).
Without DNS: You would need to remember numeric IPs instead of names.
TCP/IP (Transmission Control Protocol / Internet
Protocol)
Purpose: Foundation of all Internet communication.
TCP: Breaks data into packets and ensures reliable delivery.
IP: Routes those packets to the correct destination.
SSL/TLS (Secure Sockets Layer /
Transport Layer Security)
Purpose: Encrypts data transferred between browser and server.
Used in: HTTPS websites for secure communication.

10. Protocol Full Form Function Port Secure?
HTTP
HyperText
Transfer Protocol
Transfer web
pages
80 ❌
HTTPS
HyperText
Transfer Protocol
Secure web page
transfer
443 ✅
FTP
File Transfer
Protocol
Upload/download
files
21 ❌
SMTP
Simple Mail
Transfer Protocol
Send emails 25/587 ❌
POP3
Post Office
Protocol v3
Receive emails
(download)
110 ❌
IMAP
Internet Message
Access Protocol
Receive emails
(store on server)
143/993 ✅
DNS
Domain Name
System
Converts domain
to IP
53 ❌
TCP/IP
Transmission
Control Protocol /
Internet data
transfer
— ✅
SSL/TLS
Secure Sockets
Layer / Transport
Data encryption — ✅
WebSocket —
Real-time
communication
80/443 ✅
WebSocket Protocol
Purpose: Enables real-time two-way communication between a browser and a
server.
Used in: Chat apps, online games, live notifications, and stock updates.

11. WEB TECHNOLOGIES AND TERMS
A protocol used for
transmitting web pages over
the Internet.HTTP (HYPERTEXT TRANSFER
PROTOCOL) CGI (COMMON GATEWAY
INTERFACE) HTML (HyperText Markup
Language) XML (Extensible Markup
Language) XHTML (Extensible HyperText
Markup Language) CHTML (Compact HTML)
The standard markup
language used to create web
pages
<P>THIS IS XHTML CONTENT.</P>
<IMG SRC="IMAGE.JPG" ALT="PHOTO" />
A standard protocol for web
servers to interact with
external programs or scripts.
PERL, PYTHON, PHP, C, ETC.
Focuses on data
representation, not display.
A lightweight version of HTML
developed for mobile devices and
small screens (especially early cell
phones).

12. Node.js
Main scripting tools and technologies
used for Web API development
Python

13. Tool / Language Framework Usage Type Best For
Node.js Express.js Server-side Real-time APIs
Python Flask / FastAPI Server-side Data & AI APIs
PHP Laravel / Slim Server-side Web app APIs
Java Spring Boot Server-side Enterprise systems
Ruby Rails / Sinatra Server-side Rapid prototyping
JavaScript Fetch / Axios Client-side Consuming APIs