Hierarchy Structure
📁 inventory_management_backend/
├── 📁 app/
Main application package
│ ├── 📁 domain/
Business entities and pure domain logic
│ │ ├── 📁 models/
Domain entities
│ │ │ ├── 📄 user.py
│ │ │ └── 📄 product.py
│ │ └── 📁 services/
│ │ └── 📄 inventory_service.py
│ ├── 📁 application/
Use cases, DTOs, orchestrators, event handlers
│ │ ├── 📁 use_cases/
Business operations
│ │ │ ├── 📁 product/
│ │ │ │ ├── 📄 create_product.py
│ │ │ │ ├── 📄 get_product.py
│ │ │ │ ├── 📄 update_product.py
│ │ │ │ └── 📄 delete_product.py
│ │ │ └── 📁 user/
│ │ │ ├── 📄 register_user.py
│ │ │ └── 📄 login_user.py
│ │ ├── 📁 dto/
DTOs for requests/responses
│ │ │ ├── 📄 product_dto.py
│ │ │ └── 📄 user_dto.py
│ │ └── 📁 event_handlers/
│ │ └── 📄 inventory_events.py
│ ├── 📁 ports/
Abstract interfaces for repositories, auth, event bus
│ │ ├── 📄 product_repository.py
│ │ ├── 📄 user_repository.py
│ │ └── 📄 event_bus.py
│ ├── 📁 adapters/
Infrastructure implementations (DB, auth, events)
│ │ ├── 📁 repositories/
│ │ │ ├── 📄 product_repository_impl.py
│ │ │ └── 📄 user_repository_impl.py
│ │ ├── 📁 db/
│ │ │ ├── 📄 base.py
│ │ │ └── 📄 session.py
│ │ ├── 📁 auth/
│ │ │ └── 📄 jwt_manager.py
│ │ └── 📁 events/
│ │ └── 📄 event_publisher.py
│ ├── 📁 api/
FastAPI routers/controllers
│ │ ├── 📁 v1/
│ │ │ ├── 📄 product_router.py
│ │ │ └── 📄 user_router.py
│ │ └── 📄 dependencies.py
│ ├── 📁 config/
│ │ └── 📄 settings.py
│ ├── 📄 main.py
│ └── 📄 events.py
├── 📁 tests/
Unit & integration tests
│ ├── 📄 domain/
│ ├── 📄 application/
│ ├── 📄 adapters/
│ ├── 📄 api/
│ └── 📄 conftest.py
├── 📄 requirements.txt
├── 📄 README.md
└── 📁 alembic/
DB migrations
📁 domain/
Defines pure business logic and entities, independent of frameworks/infrastructure. Purpose: Isolate and reuse core logic.
📁 application/
Orchestrates domain logic, use cases, DTOs, and event handlers. Purpose: Implements business workflows.
📁 ports/
Abstract interfaces for repositories, auth, event bus. Purpose: Decouples business logic from infrastructure.
📁 adapters/
Infrastructure implementations—repositories, DB, auth, event publisher. Purpose: Bridges core to external systems.
📁 api/
FastAPI routers/controllers as entry points. Purpose: Adapts HTTP requests to business logic.
📁 config/
App configuration, secrets, DB settings. Purpose: Technical details kept out of core logic.
📄 main.py
App entry point, wires dependencies. Purpose: Bootstraps hexagonal application.
📁 app/
Microservice boundary (can split into submodules/services). Purpose: Enables independent deployment and scaling.
📄 main.py
Microservice entry point. Purpose: Run services independently.
📁 config/
Service-specific configuration. Purpose: Environment setup per microservice.
📁 adapters/events/
Messaging adapters for each service. Purpose: Enables async communication between microservices.
📁 tests/
Service/module-level tests. Purpose: Reliability and separation of concerns.
📁 alembic/
Service-specific DB migrations. Purpose: Schema evolution per microservice.
📁 application/event_handlers/
Handles events and triggers workflows. Purpose: Responds to system changes asynchronously.
📁 adapters/events/
Event publisher for domain/integration events. Purpose: Publishes events to brokers.
📄 events.py
Centralized event definitions. Purpose: Maintains event registry.
📄 application/dto/*_dto.py
Event payload DTOs. Purpose: Ensures structured event data.
📁 ports/event_bus.py
Event bus interface. Purpose: Decouples event logic from messaging technology.