@startuml

actor User as u
collections LOMS as l
database OrdersStorage as os
database StocksStorage as ss

u -> l : gRPC Loms.OrderCreate\n\t- user\n\t- items: []item{\n\t\t- sku\n\t\t- count\n\t  }
activate l
l -> os : order.Create()\n\tstatus=new
l -> ss : stocks.Reserve()

alt Reserve success
  l -> os : order.SetStatus(awaiting payment)
  l -> u : Response: OK (code_id=0)\n\t- orderID
else
  l -> os : order.SetStatus(failed)
  l -> u : Failed Precondition (code_id 9)
end
deactivate l

@enduml