spring-boot-modulith

# Spring Modulith for Bounded Contexts

Implements DDD bounded contexts as application modules with enforced boundaries and event-driven communication.

## Core Concepts

| Concept | Description |
|---------|-------------|
| **Application Module** | Package-based boundary = bounded context |
| **Module API** | Types in base package (public) |
| **Internal** | Types in sub-packages (encapsulated) |
| **Events** | Cross-module communication mechanism |

## Module Structure

```
src/main/java/
├── com.example/
│   └── Application.java              ← @SpringBootApplication
├── com.example.order/                ← Module: order
│   ├── OrderService.java             ← Public API
│   ├── OrderCreated.java             ← Public event
│   ├── package-info.java             ← @ApplicationModule config
│   └── internal/                     ← Encapsulated
│       ├── OrderRepository.java
│       └── OrderEntity.java
├── com.example.inventory/            ← Module: inventory
│   ├── InventoryService.java
│   └── internal/
└── com.example.shipping/             ← Module: shipping
```

Types in `com.example.order` = public API
Types in `com.example.order.internal` = hidden from other modules

## Quick Patterns

See [EXAMPLES.md](EXAMPLES.md) for complete working examples including:
- **Module Configuration** with @ApplicationModule
- **Event Publishing** with domain event records
- **Event Handling** with @ApplicationModuleListener (Java + Kotlin)
- **Module Verification Test** with PlantUML generation
- **Event Externalization** for Kafka/AMQP

## Spring Boot 4 / Modulith 2.0 Specifics

- **@ApplicationModuleListener** combines `@Async` + `@Transactional(REQUIRES_NEW)` + `@TransactionalEventListener(AFTER_COMMIT)`
- **Event Externalization** with `@Externalized` annotation for Kafka/AMQP
- **JDBC event log** ensures at-least-once delivery

## Detailed References

- **Examples**: See [EXAMPLES.md](EXAMPLES.md) for complete working code examples
- **Troubleshooting**: See [TROUBLESHOOTI