API service > Controllers
If using any of the API service controllers, the router cannot utilize the class_namespace config key
since the API controllers reside in a different namespace than the controllers used at the app-level (see routes).
Every API controller response should use the respond method,
and every exception should extend ApiHttpException or ApiServiceException (see exceptions).
This allows the execution of the appropriate filters and events, and ensures a valid API schema is always returned.
All API controllers should extend one of:
API controllers can also use any of the available controller traits. In addition, controllers can implement CrudControllerInterface.