rowland66

See my answer to WJW above. Yes, even in the face of network partition, but with system unavailability in the event of a network partition.

I think that you are misunderstanding the CAP theorem. The CAP theorem states that in the event of a network partition, a system can either be consistent or available, but not both. So a messaging system that provided exactly once message delivery would not provide availability during a network partition. However, there are many applications for which consistency is more important than availability, especially if the period of unavailability can be limited.

I think that you description of exactly once messaging is inaccurate

> This is the holy grail of messaging, and also the fountain of a lot of snake-oil.

Exactly once message delivery is quite possible with messaging systems that support transactions. When combined with other transactional resources (e.g. database) and a distributed transaction monitor, exactly once messaging works well and is rock solid reliable. The grand-daddy of message brokers IBM MQ is absolutely capable of exactly once messaging.

>> Besides, what are the other options?

How about fund university research in related technology, reduce regulation that inhibits free enterprise, open financial markets to support capital formation, lower taxes on capital gains, enforce anti-trust regulation, and cross your fingers and hope some comes from it in 20 years.

You could also spend trillions of dollars on a high tech military industrial complex. That helps also.

This is not going to do it.

Maybe I am just old because I had to Google what gaslighting meant, but as best I can tell getting gaslighted by your system architecture is really stretching the meaning of the term gaslighting to the point of absurdity.

Any idea how much of that 1.8% that issuing banks charge goes back to cardholders in the form of rewards and cash back?

Your list would be quite a bit more useful if you provided more of an explanation of what you SaaS does, and the volume of traffic it was supporting.

What you are describing here are SEPA direct debits. Many countries including the USA have a similar instrument. While it is free for the consumer from whom money is being collected, it is generally not free for the business that is collecting the money. So in that way, it is the same as credit cards, but the fee is a lot less.