The cashier selects the customer to check. The POS sends a request for the updated status of the customer. The results of this query are written to the POS database. From here, the transaction proceeds normally. If the customer is blocked or has exceeded his balance, the standard POS application takes the appropriate action.
Error handling
Since this is a query to the remote database, error handling is rather simple. If the remote database is unavailable, the POS uses the values stored in the POS database.
If connecting to the database fails, it is possible to specify a secondary server for this request as backup.