Activity 1: Introduction to Web Systems and the Internet | July 2, 2026
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Document Structure
Visual Styling
Dynamic Behavior
Served directly by Apache:
localhost:3306 | utf8mb4 | InnoDB
PK: id
PK: product_id
FK: seller_id
PK: cart_id
FK: buyer_id, product_id
PK: order_id
FK: buyer_id, product_id
PK: transaction_id
FK: order_id
PK: message_id
FK: sender_id, receiver_id
Domain Name System
localhost → 127.0.0.1
HyperText Transfer Protocol
Port 80/443
Transmission Control Protocol
Reliable Connection
Structured Query Language
Port 3306
Enter username and password
Validate & create JSON payload
Send to php/login.php
Check security, route request
Sanitize input, prepare SQL
SELECT * FROM users WHERE...
Return user record
password_verify() hash check
Format success response
Send response to browser
Store session, redirect
Dashboard loads successfully
Input validation (not relied upon)
.htaccess protection, Security headers
Prepared statements, Password hashing
Foreign keys, ACID transactions
Client, Server, Application, Database
DNS, HTTP/HTTPS, TCP/IP, SQL
users, products, cart, orders, transactions, messages
RESTful API for all operations
Three-Tier Client-Server Architecture - This system demonstrates a complete web architecture where DNS resolves addresses, HTTP enables communication, Apache routes requests, PHP processes business logic, and MySQL stores data securely.