- At Most Once Delivery: It guarantees that a particular message can either be delivered once or not at all. There can be a loss of messages but a message can never be delivered more than once.
- At Least Once Delivery: It guarantees that a particular message will always be delivered. It can be delivered multiple times but there will never be any messages lost.
- Exactly Once Delivery: It guarantees that all messages will always be delivered exactly once. Exactly once does not mean that there will be no failures or no retries. These are inevitable. The important thing is that the retries succeed. In other words, the result should be the same, whether it has been successfully processed exactly once or not.
采用事务的二步提交方式？
