Chapter 4: Back-End Fundamentals
Chapter 4: Back-End Fundamentals
4.1 Server-Side Programming
Server-side programming involves writing code that runs on the server rather than in the browser. This code handles business logic, database operations, authentication, and generates dynamic content.
Why Server-Side Programming?
- Security: Sensitive operations (database access, authentication) happen on the server
- Performance: Server can process data efficiently before sending to client
- Data Management: Centralized data storage and retrieval
- Business Logic: Complex calculations and validations run on server
Server-Side Languages:
- Node.js: JavaScript runtime for server-side development
- PHP: Popular for web development, especially with WordPress
- Python: Used with frameworks like Django and Flask
- Ruby: Used with Ruby on Rails framework
- Java: Enterprise-level applications
- C#: Microsoft stack with ASP.NET
Server-Side Tasks:
- Process HTTP requests and generate responses
- Interact with databases to store and retrieve data
- Handle user authentication and authorization
- Process form submissions and validate input
- Generate dynamic HTML or JSON responses
- Manage sessions and cookies
4.2 Database Management
Databases store and manage application data. Understanding database concepts is essential for back-end development.
Database Types:
- Relational Databases (SQL): MySQL, PostgreSQL, SQL Server - use tables with relationships
- NoSQL Databases: MongoDB, Redis, Cassandra - use documents, key-value pairs, or graphs
Relational Database Concepts:
- Tables: Collections of related data (e.g., users, products, orders)
- Rows: Individual records in a table
- Columns: Fields that define data types (name, email, age)
- Primary Key: Unique identifier for each row
- Foreign Key: Reference to another table's primary key
- Relationships: One-to-one, one-to-many, many-to-many
Database Operations:
- Create (INSERT): Add new records to tables
- Read (SELECT): Retrieve data from tables
- Update (UPDATE): Modify existing records
- Delete (DELETE): Remove records from tables
Database Design Principles:
- Normalize data to reduce redundancy
- Use appropriate data types for each field
- Create indexes for frequently queried columns
- Establish proper relationships between tables
- Plan for scalability and performance
4.3 API Development
APIs (Application Programming Interfaces) enable communication between front-end and back-end, or between different applications.
RESTful APIs: Representational State Transfer APIs use HTTP methods to perform operations:
- GET: Retrieve data (read)
- POST: Create new resources
- PUT: Update entire resource
- PATCH: Partially update resource
- DELETE: Remove resource
API Design Best Practices:
- Use clear, consistent URL patterns (/api/users, /api/products)
- Return appropriate HTTP status codes (200, 201, 404, 500)
- Use JSON for data exchange
- Implement proper error handling
- Document APIs clearly
4.4 Authentication and Security
Back-end systems must handle user authentication and implement security measures.
Authentication Methods:
- Session-Based: Server stores session data, client receives session ID
- Token-Based (JWT): Stateless authentication using JSON Web Tokens
- OAuth: Third-party authentication (Google, Facebook, GitHub)
Security Best Practices:
- Hash passwords (never store plain text)
- Validate and sanitize all user input
- Protect against SQL injection
- Use HTTPS for encrypted communication
- Implement rate limiting
- Keep dependencies updated