where can i handle business logic

[haniyasin]

hi this is a great framework for auto CRUD api , can you please point out where can handle my business logic for an auto created API is it with custom plugins and custom attributed attached to zmodel or where , use cases:
1- before saving call another API (zenstack or external) do some data modification
2- after saving call another service and trigger a scheduler or a workflow or an email
3- create custom API the doc mentions this but nothing to explain how
4-maybe calling a stored procedure before saving and modify data according to result from the SP
there alot of other use cases , i tried to search for youtube, docs, articles but all are simple CRUD operations
appreciate your help to better understand the full potential of the framework