> High throughput and low latency stream processing with exactly-once guarantees.
Precisely how is this possible in a real-world distributed system? At-least-once and at-most-once are possible with different distribution methods, but "exactly-once" is, well, I have yet to see it actually implemented (even theoretically, see the Two Generals thought experiment). Even their checkpointing algorithm has an assumption that the underlying transport is "exactly once" and "FIFO ordered".
If I had to guess, I'd say that what they're really guaranteeing is "at most once" message delivery. Unfortunately, that has a very different meaning from "exactly once".
Precisely how is this possible in a real-world distributed system? At-least-once and at-most-once are possible with different distribution methods, but "exactly-once" is, well, I have yet to see it actually implemented (even theoretically, see the Two Generals thought experiment). Even their checkpointing algorithm has an assumption that the underlying transport is "exactly once" and "FIFO ordered".
If I had to guess, I'd say that what they're really guaranteeing is "at most once" message delivery. Unfortunately, that has a very different meaning from "exactly once".
http://bravenewgeek.com/you-cannot-have-exactly-once-deliver...