how many messages a second can be handled synchronously?
what happens if the message arrives twice?
what happens if the data centre is blown up/goes up in flames?
how did the other data centre guarantee to be in a consistent state?
how did the backup system automatically take over?
These systems have to be up and running all the time and there can't be an option for mistakes!
When I say message I’m think of the equivalent of a TCP packet. So you have a bunch of error checking and ACKs flying about. But only one message to actually move money.
Single message systems already exist, most US card transactions move over a single message system.
> there can’t be an option for mistakes!
This is where you’re wrong. Mistakes happen all the time when moving money, a big part of any banks operations is cleaning up those mistakes.
These systems have to be up and running all the time and there can't be an option for mistakes!