E-Commerce Application with Spring Cloud OpenFeign Bank Integration

This project demonstrates a complete e-commerce application integrated with a banking system using Spring Cloud OpenFeign for microservices communication.

Architecture Overview

• EcommerceApp (Port 8081): Main e-commerce application
• BankApp (Port 8080): Banking service for payment processing
• Integration: OpenFeign client for seamless communication

Local setup with Kafka

MacOS

brew services start zookeeper
brew services start kafka
kafka-topics --create --topic test --bootstrap-server localhost:9092 --partitions 2 --replication-factor 1
# Verify topics
kafka-topics --list --bootstrap-server localhost:9092

Features Implemented

E-Commerce Application Features

1. User Registration & Login

   • User registration with bank account linking
   • Authentication system
   • User profile management

2. Product Management

   • Product catalog with categories
   • Search functionality (works with/without login)
   • Stock management

3. Shopping Cart

   • Add/remove products
   • Quantity management
   • Cart total calculation

4. Purchase System

   • Order creation with bank verification
   • Payment processing via OpenFeign
   • Order status tracking

5. Dashboard Analytics

   • Monthly order reports
   • Date range filtering
   • Purchase history

Bank Integration Features

1. Account Verification

   • Verify customer bank account exists
   • Real-time account validation

2. Payment Processing

   • Check sufficient funds before purchase
   • Transfer funds from customer to e-commerce account
   • Transaction ID tracking

OpenFeign Integration

BankServiceClient

@FeignClient(name = "bank-service", url = "${bank.service.url}")
public interface BankServiceClient {
    @GetMapping("/api/accounts/{accountNumber}")
    ResponseEntity<Account> getAccountByNumber(@PathVariable String accountNumber);
    
    @PostMapping("/api/transfers")
    ResponseEntity<Transaction> transferFunds(@RequestBody TransferRequest request);
}

API Endpoints

User Management

• POST /api/users/register - Register new user
• POST /api/users/login - User login
• GET /api/users/{id} - Get user details

Product Management

• GET /api/products - Get all products
• GET /api/products/search?keyword={keyword} - Search products
• GET /api/products/category/{category} - Get products by category

Shopping Cart

• POST /api/cart/add - Add product to cart
• GET /api/cart/user/{userId} - Get cart items
• DELETE /api/cart/remove/{cartItemId} - Remove from cart

Order Management

• POST /api/orders/purchase/{userId} - Purchase cart items
• GET /api/orders/user/{userId} - Get user orders
• GET /api/orders/dashboard/{userId} - Get monthly dashboard

Demo Endpoints

• GET /api/demo/complete-flow - Demonstrate full e-commerce flow
• GET /api/demo/features-overview - List all features
• GET /api/demo/test-bank-connectivity - Test bank integration

Setup Instructions

1. Start BankApp (Port 8080)

cd BankApp
mvn spring-boot:run

2. Start EcommerceApp (Port 8081)

cd ecommerceapp
mvn spring-boot:run

3. Test the Integration

Complete Demo Flow

curl http://localhost:8081/api/demo/complete-flow

Test Bank Connectivity

curl http://localhost:8081/api/demo/test-bank-connectivity

Sample Data

Pre-created Bank Accounts

• ECM001: E-commerce company account (receives payments)
• CUST001: John Doe - $1000.00 balance
• CUST002: Jane Smith - $750.00 balance

Sample Products

• Classic Denim Jacket - $79.99
• Cotton T-Shirt - $24.99
• Skinny Jeans - $59.99
• Summer Dress - $89.99
• Sneakers - $99.99

Testing the Complete Flow

1. Register User: Create user with bank account CUST001
2. Login: Authenticate user
3. Search Products: Find products by keyword
4. Add to Cart: Add selected products
5. Verify Bank Account: Check account exists and has funds
6. Purchase: Process payment via OpenFeign integration
7. Dashboard: View purchase history

Error Handling

• Bank service connectivity issues
• Insufficient funds validation
• Stock availability checks
• Invalid account number handling

Technology Stack

• Spring Boot 3.5.3
• Spring Cloud OpenFeign
• Spring Data JPA
• H2 Database
• Lombok
• Maven

Database Configuration

Both applications use H2 in-memory databases:

• BankApp: jdbc:h2:mem:test
• EcommerceApp: jdbc:h2:mem:ecommerce

Access H2 consoles:

• BankApp: http://localhost:8080/h2-console
• EcommerceApp: http://localhost:8081/h2-console