Today you can use the API remotely to create a serverside backup. You can use GBAK to create a remote backup (e.g. via Internet). But you can't use API to create remote backup, i.e. create a backup serverside and flush it to the client.
As using GBAK is very very slow over internet (testcase 10MB database backup takes less than 2 seconds when done locally, and more than 5 minutes through a 20MBit internet connection) ) it is a must to improve this function to make it possible to offer remote hosting for customers.