1️⃣ Hexagonal Architecture (Ports & Adapters)
💡 Best for: Scalable, maintainable, and loosely coupled microservices.
✅ Key Concepts:

• Core business logic (domain layer) is independent of frameworks and external dependencies.
• Uses ports (interfaces) and adapters (implementations) to decouple external technologies (DB, API, MQ, etc.).

📦 Structure Example:
arduino
CopyEdit
com.example.app
│── application    // Use Cases (Application Layer)
│   ├── service   // Business logic services
│   ├── dto       // Data Transfer Objects
│   ├── port      // Interfaces for inbound/outbound ports
│
│── domain         // Core Business Logic (Domain Layer)
│   ├── model     // Domain entities (Aggregates, Value Objects)
│   ├── repository// Domain-driven repository interfaces
│   ├── event     // Domain events (if using Event-Driven Design)
│
│── infrastructure // Adapters (Infrastructure Layer)
│   ├── adapter
│   │   ├── rest  // Controllers (Input Adapter)
│   │   ├── db    // Database persistence (Output Adapter)
│   │   ├── mq    // Message Queue adapters (Kafka, RabbitMQ, etc.)
│── config         // Configuration (Spring Boot, Database, Security)
🔹 Why use it?

• Decouples business logic from frameworks (Spring Boot, database, etc.).
• Easier to test and maintain.
• Supports multiple implementations (e.g., PostgreSQL, MongoDB, Kafka, RabbitMQ).