A modern Point of Sale (POS) system backend built with .NET 9, demonstrating professional-grade software development skills including C#, Entity Framework Core, SQL Server, XML configuration, and RESTful API design.
- Product Management: CRUD operations for products with categories and inventory tracking
- Order Processing: Complete order lifecycle management with payment processing
- Database Integration: Entity Framework Core with SQL Server LocalDB
- XML Configuration: Advanced XML-based configuration management with validation
- RESTful API: Well-designed REST endpoints with proper HTTP status codes
- Data Validation: Comprehensive input validation and error handling
- Business Logic: Transaction management, stock control, and pricing calculations
- Documentation: Swagger/OpenAPI integration for API documentation
- Logging: Structured logging throughout the application
- Health Checks: Database connectivity monitoring
- .NET 9.0 - Modern C# framework
- ASP.NET Core Web API - RESTful API framework
- Entity Framework Core - Object-relational mapping
- SQL Server LocalDB - Development database
- Swagger/OpenAPI - API documentation
- XML Processing - Configuration management
- Dependency Injection - Service registration and lifecycle management
- .NET 9.0 SDK or later
- Visual Studio 2022 or VS Code
- SQL Server LocalDB (included with Visual Studio)
# Navigate to project directory
cd POSSystem
# Restore dependencies
dotnet restore
# Build the project
dotnet buildThe application uses SQL Server LocalDB and will automatically create the database on first run with sample data.
dotnet runThe API will be available at:
- Swagger UI:
https://localhost:7065(default) - Health Check:
https://localhost:7065/health
- Complex relationships with proper foreign keys
- Fluent API configuration for database schema
- Repository pattern with service layer abstraction
- Transaction management for data consistency
- Seed data initialization
- Custom XML configuration parser
- Validation and error handling
- Caching and performance optimization
- Type-safe configuration access
- Support for complex nested structures
- RESTful endpoint design following best practices
- Proper HTTP status codes and error responses
- Input validation with model binding
- Pagination and filtering support
- Consistent DTO patterns
- Order processing with inventory management
- Payment processing simulation
- Automatic tax and total calculations
- Stock level tracking and validation
- Order status workflow management
GET /api/products- Get all products with filtering and paginationGET /api/products/{id}- Get specific productPOST /api/products- Create new productPUT /api/products/{id}- Update existing productDELETE /api/products/{id}- Soft delete productGET /api/products/low-stock- Get low stock products
POST /api/orders- Create new orderGET /api/orders/{id}- Get specific orderGET /api/orders- Get orders by date rangePATCH /api/orders/{id}/status- Update order statusPOST /api/orders/{id}/payment- Process paymentGET /api/orders/{id}/total- Calculate order total
GET /health- Health check with database connectivity
POSSystem/
├── Controllers/ # API Controllers
│ ├── ProductsController.cs
│ └── OrdersController.cs
├── Models/ # Domain Models
│ ├── Product.cs
│ ├── Category.cs
│ ├── Order.cs
│ ├── OrderItem.cs
│ └── Customer.cs
├── Data/ # Data Layer
│ └── POSContext.cs
├── Services/ # Business Logic
│ ├── IOrderService.cs
│ └── OrderService.cs
├── Configuration/ # XML Configuration
│ ├── ConfigurationModels.cs
│ ├── XmlConfigurationService.cs
│ └── pos-config.xml
└── Program.cs # Application Startup
The application includes seeded data:
- Categories: Electronics, Clothing, Food & Beverages
- Products: Sample products with stock quantities
- Configuration: Complete XML configuration example
The system uses XML-based configuration for:
- Tax rates and currency settings
- Payment method configuration
- Security policies
- Reporting settings
- Inventory thresholds
Example configuration access:
var taxRate = configService.GetSetting<decimal>("general.taxrate", 0.08m);- Provides robust ORM capabilities with excellent performance
- Code-first approach for database schema management
- Built-in support for migrations and seeding
- Strong typing and LINQ query support
- Demonstrates XML parsing and manipulation skills
- Provides hierarchical configuration structure
- Supports validation and schema enforcement
- Easily readable and maintainable by non-developers
- Separates business logic from API controllers
- Enables easier unit testing and mocking
- Promotes code reusability and maintainability
- Supports dependency injection patterns
For production deployment, consider:
- Database: Migrate to full SQL Server instance
- Authentication: Add JWT or OAuth2 authentication
- Caching: Implement Redis for performance
- Monitoring: Add Application Insights or similar
- Security: Enable HTTPS, add rate limiting
- Logging: Configure structured logging to external systems
This project demonstrates:
- Clean Architecture: Separation of concerns with proper layering
- SOLID Principles: Dependency inversion, single responsibility
- Error Handling: Comprehensive exception management
- Performance: Async/await patterns, efficient queries
- Maintainability: Clear code structure and documentation
- Testability: Service abstractions and dependency injection
This project is created as a demonstration of backend development skills for evaluation purposes.
Built with care using .NET 9 and modern C# practices