@startuml

actor User as u
collections Cart as c
database CartStorage as cs
collections Order as o

u -> c : POST /checkout/<user_id>
activate c
c -> cs : cart.GetItemsByUserID
c -> o : gRPC Loms.OrderCreate\n\t- user\n\t- []item
c -> cs : cart.DeleteItemsByUserID

c -> u : Response: 200 OK

deactivate c

@enduml