Re:Building for the Blockchain
by sushisource on Tuesday January 09, 2018 @05:38PM
(#16110836)
I believe the major players (Visa being one of them, and I know a Visa engineer) use formal verification for the actual money-handling code. Obviously, yeah, there could be mistakes with the verifier, etc, but the problems they experience are relegated to the "couldn't do this transaction" variety, rather than the "we did this transaction wrong" variety.
What sushisource said. 99.9999(...)% reliability with a fallback around inconsistencies of, “we’ll block this transaction,” as opposed to, “your money? What money?” (Apply to logistics, shipping, etc.)
15 transactions a day? I'm guessing that number is in the thousands, easily.
Manual input at restaurants alone should hit that threshold. As you correctly pointed out, reversing the transaction is very low friction, which is something I've not yet seen presented in any blockchain based solution.
Visa claims to handle 150 million transactions a day [0].
(150 * 10^6) * (1 - .999999999) =~ 0.15
[0] - https://usa.visa.com/run-your-business/small-business-tools/...
But, separately, if you asked me if I wanted to use something to store/transmit value that was only reliable 99.9999999% of the time, I would immediately say no. At Visa scale, that means 15 transactions a day are incorrect - not delayed, just straight up incorrect. Maybe that already happens and we just don't hear about it because they can fix it without any one noticing or it's just small enough to not be noticed. But it is still unnerving.