That said, one detail I left out is that this transaction is distributed across 4 separate systems, so it's not quite as simple as a database lock. And I wouldn't do a long db lock unless it was some kind of pessimistic offline lock :)
But we're mostly worrying about the mobile app acknowledging the response so the same principle stands - we need the mobile app to ACK :)
That said, one detail I left out is that this transaction is distributed across 4 separate systems, so it's not quite as simple as a database lock. And I wouldn't do a long db lock unless it was some kind of pessimistic offline lock :)
But we're mostly worrying about the mobile app acknowledging the response so the same principle stands - we need the mobile app to ACK :)