1. Setting Up the Environment

Goal: Prepare a development environment tailored to the backend framework you choose.

Steps:

• Install a Backend Framework:

  • For PHP: Use a framework like Laravel for ease of development and MVC architecture.
    • Install Laravel: composer create-project laravel/laravel my-project
  • For Node.js: Use Express.js to build APIs.
    • Install Express:

      mkdir my-project && cd my-project
      npm init -y
      npm install express
      

  • For Python: Use Flask or Django for robust API building.
    • Install Flask: pip install flask
    • Install Django: pip install django

• Dependencies and Tools:

  • Ensure you have tools like Postman (for API testing) and Ngrok (for exposing local servers).
  • Install required libraries or modules for handling API requests.
    • PHP: Guzzle HTTP Client (composer require guzzlehttp/guzzle)
    • Node.js: Axios or Node-Fetch (npm install axios)
    • Python: Requests library (pip install requests)

2. Folder Structure

Goal: Maintain organized and scalable code by structuring project files systematically.

Example Folder Structure:

project-root/
├── controllers/      # Contains API logic
├── routes/           # Defines API routes
├── config/           # Stores configuration files (e.g., API keys, environment variables)
├── utils/            # Helper functions or utilities
├── tests/            # Unit and integration tests
└── main entry file   # app.js (Node.js), index.php (PHP), etc.

Benefits:

• Easy navigation and debugging.
• Separation of concerns ensures better maintainability.

3. Setting Up Routes

Goal: Define endpoints for handling specific API operations like token generation and transaction initiation.

Implementation Example:

• In PHP (Laravel):

  Route::get('/generate-token', [MpesaController::class, 'generateToken']);
  Route::post('/initiate-transaction', [MpesaController::class, 'initiateTransaction']);
  

• In Node.js (Express):

  const express = require('express');
  const app = express();
  
  app.get('/generate-token', (req, res) => {
      // Call token generation logic
      res.send("Token Generated");
  });
  
  app.post('/initiate-transaction', (req, res) => {
      // Call transaction logic
      res.send("Transaction Initiated");
  });
  
  app.listen(3000, () => console.log('Server running on port 3000'));
  

• In Python (Flask):

  from flask import Flask
  
  app = Flask(__name__)
  
  @app.route('/generate-token', methods=['GET'])
  def generate_token():
      return "Token Generated"
  
  @app.route('/initiate-transaction', methods=['POST'])
  def initiate_transaction():
      return "Transaction Initiated"
  
  if __name__ == "__main__":
      app.run(debug=True)
  

4. Configuration Files

Goal: Securely store sensitive information like consumer keys, secrets, and callback URLs.

Best Practices:

• Use environment variables to store sensitive data.
  • PHP: Use .env file with dotenv package.

    MPESA_CONSUMER_KEY=your_consumer_key
    MPESA_CONSUMER_SECRET=your_consumer_secret
    CALLBACK_URL=https://yourdomain.com/callback
    

  • Node.js: Use dotenv package.

    MPESA_CONSUMER_KEY=your_consumer_key
    MPESA_CONSUMER_SECRET=your_consumer_secret
    CALLBACK_URL=https://yourdomain.com/callback
    

    Code to load:

    require('dotenv').config();
    const consumerKey = process.env.MPESA_CONSUMER_KEY;
    

  • Python: Use os or dotenv library.

    import os
    from dotenv import load_dotenv
    
    load_dotenv()
    consumer_key = os.getenv("MPESA_CONSUMER_KEY")
    

5. Testing the Backend

Goal: Verify that the backend endpoints work as expected before integrating them with Mpesa APIs.

Steps:

1. Install Postman: Use Postman to send requests to your backend.

   • GET Request: Test the /generate-token endpoint to verify token generation logic.
   • POST Request: Test /initiate-transaction with required parameters like amount and phone number.

2. Use Ngrok: Expose your local server to the internet to test callbacks from Mpesa.

   • Install Ngrok: npm install -g ngrok or download it from Ngrok’s website.
   • Start Ngrok:

     ngrok http 3000
     

   • Use the generated URL (e.g., https://abcd1234.ngrok.io) as your callback URL in Mpesa configurations.

3. Debug Errors:

   • Use logs in your code to troubleshoot any issues.
     • PHP: Use Log::info("Message").
     • Node.js: Use console.log("Message").
     • Python: Use print("Message").