Step one: ignore the prefix, this has nothing to do with hex/six. And "ogon" meaning sides or struggle. The sides represent interfaces. This arch really means

Step one: ignore the prefix, this has nothing to do with hex/six. And "ogon" meaning sides or struggle. The sides represent interfaces. This arch really means use interfaces based on business use cases / domains. Call the User service/module and pass user ids into a billing service/module. Each service is over a defined interface (adaptor) that allows separation of concerns and separate data stores. You could use an in-memory port of the billing service and a real db for the user service service because both implementations leverage the same adapter code