2.12 RocketMQ Transaction Messages

1. What Are RocketMQ Transaction Messages?

• Traditional local message tables depend on a message table in the database.
• RocketMQ transactions encapsulate the local-message-table approach by moving the local message table into MQ, solving the atomicity problem between Producer-side message sending and local transaction execution.

2. How RocketMQ Transaction Messages Work

1. Service A sends a half message to MQ.
2. Service A receives MQ’s confirmation for the half message.
3. Service A executes the local transaction.
4. Service A sends a commit/rollback message to MQ according to the execution result of the local transaction.
5. If the confirmation message in step 2 is lost, or execution of the local transaction in step 3 times out, MQ sends the half-message confirmation to Service A again.
6. Service A checks the local transaction status.
7. Service A sends a commit/rollback message to MQ according to the local transaction status.
8. After MQ receives a commit message, it sends the message to Service B. If it receives a rollback message, it discards the message.

3. References

• If Someone Asks You About Distributed Transactions Again, Send Them This Article - Juejin
• Transaction example - Apache RocketMQ
• The Design Of Transactional Message - Apache RocketMQ