Module 1: Fundamentals of REST - Understanding the Core Principles

• Theoretical Concepts:
  • What is REST? Understanding the Representational State Transfer architectural style for building web services.
  • Principles of REST:

    • Statelessness: Each request from the client to the server must contain all the information needed to understand the request. The server should not store any client context between requests.

    • Uniform Interface: Interactions between client and server should be standardized through a consistent interface. This includes resource identification, manipulation through representations, self-descriptive messages, and hypermedia as the engine of application state (HATEOAS).

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    • Resource-Based: The core concept of REST is the resource, which represents an object or entity with an associated URI (Uniform Resource Identifier).

  • HTTP Methods:
    • GET: Retrieve a representation of a resource.
    • POST: Create a new resource.
    • PUT: Update an existing resource, replacing the entire resource.
    • PATCH: Partially update an existing resource.
    • DELETE: Remove a resource.
  • HTTP Status Codes: Understanding common status codes and their meanings (e.g., 200 OK, 201 Created, 400 Bad Request, 401 Unauthorized, 404 Not Found, 500 Internal Server Error).
  • HTTP Headers: Understanding important headers like Content-Type, Authorization, Accept, etc., in requests and responses.
  • Request/Response Lifecycle: The flow of a request from the client to the server and the server's response.
  • Resource Naming Conventions: Using nouns (plural) for resource names (e.g., /users, /products).
  • API Versioning Best Practices: Different strategies for versioning your API (URI path, headers).
• Real-World Examples:
  • Retrieving user data: GET /api/v1/users/123
  • Creating a new product: POST /api/v1/products with product data in the request body.
  • Updating a user's email: PATCH /api/v1/users/123 with the new email in the request body.
  • Deleting a product: DELETE /api/v1/products/456
• Industry Standards:
  • Using appropriate HTTP methods for intended actions.
  • Returning relevant status codes to indicate the outcome of the request.
  • Utilizing headers for content negotiation and metadata.
• Checkpoint 1: You should have a solid understanding of the fundamental principles of REST and how HTTP methods and status codes are used in API communication.

Module 2: API Design Best Practices - Crafting Elegant and Usable APIs

• Theoretical Concepts:

  • Designing RESTful Endpoints and Route Structures: Creating logical and intuitive endpoint structures that reflect your resources and their relationships (e.g., /users/{userId}/orders).
  • Query Parameters: Using query parameters for filtering, sorting, and searching resources (e.g., /products?category=electronics&sortBy=price&order=asc).
  • Request Bodies: Structuring request bodies (typically in JSON format) for sending data to the server (e.g., for creating or updating resources).
  • Pagination: Implementing pagination to handle large collections of resources (e.g., using limit and offset or cursor-based pagination).
  • Request Validation: Validating incoming request data on the server-side to ensure data integrity and prevent errors.
  • Data Sanitization: Cleaning and escaping user-provided data to prevent security vulnerabilities like cross-site scripting (XSS) and SQL injection.
  • Response Standardization: Defining a consistent structure for API responses (including success and error responses).
  • Error Handling: Designing informative error responses with appropriate status codes and error messages.

• Real-World Examples:

  • Filtering users by status: /api/v1/users?status=active

  • Paginating products: /api/v1/products?page=2&limit=10

  • Standardized error response:

    JSON

    {
      "status": "error",
      "message": "Invalid input",
      "details": {
        "email": "Email address is not valid"
      }
    }
    

• Industry Standards:

  • Using clear and consistent endpoint naming.
  • Implementing robust validation and sanitization.
  • Providing informative and standardized error responses.

• Checkpoint 2: You should be able to design well-structured and user-friendly RESTful APIs, incorporating best practices for endpoint design, data handling, and error management.

Module 3: Building REST APIs (Node.js + Express) - Bringing Your Design to Life

• Theoretical Concepts:

  • Project Setup: Initializing a Node.js project with npm or yarn, installing Express.
  • Routing: Defining API endpoints and associating them with handler functions using Express Router.
  • Middleware: Understanding and using middleware functions for tasks like request logging, authentication, data parsing (body-parser), and error handling.
  • Modular Architecture: Organizing your codebase into logical modules (controllers for handling request logic, services for business logic, models for data interaction).
  • Connecting to Databases: Integrating with databases like PostgreSQL (using pg or Prisma) or MongoDB (using Mongoose).
  • Testing Endpoints: Using tools like Postman or Insomnia to send HTTP requests to your API endpoints and inspect the responses.

• Implementation Examples (Node.js + Express):

  JavaScript

  // app.js
  const express = require('express');
  const app = express();
  const port = 3000;
  
  app.use(express.json()); // Middleware for parsing JSON request bodies
  
  // Routes
  const userRoutes = require('./routes/users');
  app.use('/api/v1/users', userRoutes);
  
  // Error handling middleware
  app.use((err, req, res, next) => {
    console.error(err.stack);
    res.status(500).send('Something broke!');
  });
  
  app.listen(port, () => {
    console.log(`Server listening on port ${port}`);
  });
  

  JavaScript

  // routes/users.js
  const express = require('express');
  const router = express.Router();
  const userController = require('../controllers/userController');
  
  router.get('/', userController.getAllUsers);
  router.get('/:id', userController.getUserById);
  router.post('/', userController.createUser);
  router.put('/:id', userController.updateUser);
  router.delete('/:id', userController.deleteUser);
  
  module.exports = router;
  

// controllers/userController.js

const userService = require('../services/userService');

exports.getAllUsers = async (req, res) => {
  try {
    const users = await userService.getAllUsers();
    res.json(users);
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
};

// ... other controller methods

- **Hands-on Assignments:**
    - Set up a basic Express.js project.
    - Create routes for different resources.
    - Implement middleware for logging requests and validating data.
    - Build a modular architecture with controllers, services, and models.
    - Connect your API to a PostgreSQL or MongoDB database.
    - Test your API endpoints using Postman or Insomnia.
- **Checkpoint 3:** You should be able to build functional RESTful APIs using Node.js and Express, following a modular architecture and connecting to a database.

**Module 4: Authentication & Authorization - Securing Your API**

- **Theoretical Concepts:**
    - **JWT-Based Auth Flow:** Understanding the process of generating, issuing, and verifying JSON Web Tokens (JWTs) for authentication (access tokens and refresh tokens).
    - **Role-Based Access Control (RBAC):** Implementing different levels of access based on user roles (e.g., admin, user).
    - **Permission-Based Access Control:** Defining granular permissions for specific actions on resources.
    - **Secure Password Handling:** Using `bcrypt` to hash and salt passwords before storing them in the database.
    - **Rate Limiting:** Implementing mechanisms to limit the number of requests a client can make within a specific time frame to prevent abuse.
    - **CORS (Cross-Origin Resource Sharing):** Configuring CORS headers to control which domains can access your API.