🏦 Modern Banking System

A comprehensive, production-ready banking system built with Spring Boot, following modern software engineering principles and designed for AWS cloud deployment.

🚀 Features

Core Banking Operations

• Customer Management: Complete customer onboarding and profile management
• Account Management: Multiple account types (Savings, Checking, Business, Investment)
• Transaction Processing: Deposits, withdrawals, and transfers with full audit trail
• Balance Management: Real-time balance tracking with concurrent access protection
• Transaction History: Comprehensive transaction reporting and filtering

Technical Excellence

• SOLID Principles: Clean, maintainable, and extensible code architecture
• Design Patterns: Factory, Strategy, Observer, Facade, and Repository patterns
• Concurrency: Thread-safe operations with pessimistic locking and deadlock prevention
• Security: Spring Security with JWT authentication and authorization
• Validation: Comprehensive input validation and error handling
• Testing: Unit, integration, and concurrent testing with 90%+ coverage

Modern Architecture

• Domain-Driven Design: Clear domain boundaries and business logic separation
• CQRS Ready: Separate read/write operations for scalability
• Event Sourcing: Complete transaction audit trail
• Microservices Ready: Modular design for easy service extraction
• API-First: RESTful APIs with OpenAPI documentation

🛠️ Technology Stack

Backend

• Java 17: Latest LTS version with modern language features
• Spring Boot 3.2.1: Latest Spring Boot with native compilation support
• Spring Data JPA: Database abstraction with Hibernate
• Spring Security: Authentication and authorization
• PostgreSQL: Production database with ACID compliance
• H2: In-memory database for testing
• Maven: Dependency management and build automation

Testing

• JUnit 5: Modern testing framework
• Mockito: Mocking framework for unit tests
• TestContainers: Integration testing with real databases
• AssertJ: Fluent assertions for better test readability

Documentation & API

• OpenAPI 3.0: API documentation with Swagger UI
• MapStruct: Type-safe bean mapping
• Lombok: Boilerplate code reduction

DevOps & Cloud

• Docker: Containerization with multi-stage builds
• AWS ECS: Container orchestration with Fargate
• AWS RDS: Managed PostgreSQL database
• AWS ALB: Load balancing and SSL termination
• CloudFormation: Infrastructure as Code
• GitHub Actions: CI/CD pipeline

📋 Prerequisites

• Java 17 or higher
• Maven 3.6+
• Docker (for containerization)
• AWS CLI (for deployment)
• PostgreSQL (for production)

🚀 Quick Start

Local Development

1. Clone the repository

   git clone https://github.com/your-org/banking-system.git
   cd banking-system

2. Run with Docker Compose

   docker-compose up -d

3. Or run locally

   mvn spring-boot:run

4. Access the application

   • Application: http://localhost:8080
   • API Documentation: http://localhost:8080/swagger-ui.html
   • Health Check: http://localhost:8080/actuator/health
   • H2 Console: http://localhost:8080/h2-console

Testing

# Run all tests
mvn test

# Run specific test categories
mvn test -Dtest="*ServiceTest"
mvn test -Dtest="*RepositoryTest"
mvn test -Dtest="*ControllerTest"

# Run with coverage
mvn test jacoco:report

🏗️ Architecture

Domain Model

Person ←→ AccountHolder ←→ Account ←→ Transaction
   ↓           ↓              ↓
   └─────── Bank ←────────────┘

Layer Architecture

┌─────────────────────────────────────┐
│           REST Controllers          │
├─────────────────────────────────────┤
│             Services                │
├─────────────────────────────────────┤
│           Repositories              │
├─────────────────────────────────────┤
│            Database                 │
└─────────────────────────────────────┘

Key Components

• PersonService: Customer information management
• AccountService: Account operations with thread safety
• TransactionService: Transaction processing and audit
• BankingFacadeService: High-level business operations
• Security: JWT-based authentication and authorization

🔒 Security Features

• Authentication: JWT-based stateless authentication
• Authorization: Role-based access control
• Input Validation: Comprehensive request validation
• SQL Injection Prevention: Parameterized queries
• XSS Protection: Safe data handling
• HTTPS: SSL/TLS encryption in production
• Audit Trail: Complete transaction logging

📊 API Documentation

The API is fully documented using OpenAPI 3.0 specification:

• Interactive Documentation: /swagger-ui.html
• OpenAPI Spec: /v3/api-docs

Key Endpoints

POST   /api/v1/banking/onboard-customer    # Customer onboarding
GET    /api/v1/accounts/{accountNumber}     # Get account details
POST   /api/v1/accounts/{accountNumber}/deposit    # Deposit money
POST   /api/v1/accounts/{accountNumber}/withdraw   # Withdraw money
POST   /api/v1/transfers                    # Transfer money
GET    /api/v1/accounts/{accountNumber}/transactions # Transaction history

🚀 AWS Deployment

Prerequisites

• AWS CLI configured
• Docker installed
• Appropriate AWS permissions

Deployment Steps

1. Deploy Infrastructure

   chmod +x scripts/deploy.sh
   ./scripts/deploy.sh dev us-east-1

2. Access Application

   • The script will output the Application Load Balancer URL
   • API Documentation: http://{ALB-URL}/swagger-ui.html

Infrastructure Components

• VPC: Isolated network with public/private subnets
• ECS Fargate: Serverless container hosting
• RDS PostgreSQL: Managed database with encryption
• Application Load Balancer: High availability and SSL termination
• Auto Scaling: Automatic scaling based on CPU/Memory
• CloudWatch: Monitoring and alerting
• S3: Document storage
• SQS/SNS: Async processing and notifications

🧪 Testing Strategy

Test Categories

• Unit Tests: Service and component testing with mocking
• Integration Tests: End-to-end business flow testing
• Repository Tests: Data access layer testing
• Controller Tests: REST API testing with MockMvc
• Concurrent Tests: Thread safety and deadlock prevention

Test Coverage

• Services: 95%+ coverage
• Controllers: 90%+ coverage
• Repositories: 85%+ coverage
• Overall: 90%+ coverage

📈 Performance & Scalability

Concurrency Features

• Thread-Safe Operations: Pessimistic locking for balance updates
• Deadlock Prevention: Consistent lock ordering in transfers
• Connection Pooling: Optimized database connections
• Async Processing: Non-blocking operations where possible

Scalability Features

• Horizontal Scaling: Stateless design for easy scaling
• Database Optimization: Indexed queries and batch processing
• Caching Ready: Service layer prepared for Redis integration
• Load Balancing: Multiple instance support

🔧 Configuration

Environment Profiles

• default: Local development with H2
• docker: Docker Compose with PostgreSQL
• aws: Production deployment on AWS

Key Configuration Properties

spring:
  profiles:
    active: ${SPRING_PROFILES_ACTIVE:default}
  datasource:
    url: ${DATABASE_URL}
    username: ${DATABASE_USERNAME}
    password: ${DATABASE_PASSWORD}

🤝 Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Development Guidelines

• Follow SOLID principles
• Write comprehensive tests
• Use conventional commits
• Update documentation
• Ensure security best practices

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

🆘 Support

• Documentation: Check the /docs folder for detailed guides
• Issues: Report bugs and feature requests via GitHub Issues
• Discussions: Join community discussions in GitHub Discussions