- record training history app
- actix-web
- sqlx
- mysql5.7
- make .env and following enviromental variable
- DATABASE_URL
- domain
- core domain object. repository interface
- not to depend other layer
- middleware
- custom functions in the back of framework
- repository
- store, find object from databases.
- easily change?
- usecase
- business logic.
- organize domain,repository...
- utils
- commone feature called from anylayer.
- need to make good abstraction design.