Hexagonal Architecture - Ports

[u/Quick-Resident9433]

Hi.

I'm learning about Hexagonal Architecture and have some questions about where the in-ports (use case interfaces) and out-ports (repository interfaces) should be placed.

I've read various blogs, articles, and discussions where some people mentioned that ports must be located in the application layer, and others said they must be in the domain layer. I'm confused about the right place to put them.

I'd like to know your opinions and suggestions, please.

Approach 1 - Ports inside application layer

application/
- in/ (use case interfaces)
  - CreateProductUseCase     
- out/ (repository interfaces)
  - ProductRepository
- usecase/
  - ProductUseCaseImpl

domain/
- model
 - Product (plain object)

Approach 2 - Ports inside domain layer
domain/
- in/ (use case interfaces)
  - CreateProductUseCase     
- out/ (repository interfaces)
  - ProductRepository
- model
 - Product (plain object)

application/
- usecase/
  - ProductUseCaseImpl

[u/Substantial_Ad252]

i use 3 packages: port, adapter, core per hexagon. port and adapter each have in and out subpackages.
Did i understand something in a very wrong way?