Saga rollback/compensating transaction example

Axon Framework
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1

Hi,

Is there an example about how can we handle SAGA rollback/compensating transaction using Axon. I am tired of searching but didn’t get one.

2

Hi Manish,

A compensating action in Axon is also done with a command/event. If we take the example of a bank transfer and the amount is deducted from bank account A but cannot be added to bank account B a compensating command should be sent to bank account A to add the amount again.

I hope this answers your question

Yvonne

3

So does that mean, compensating actions should be manually implemented using command/events to revert each process that was executed on the way? Basically compensating transaction is nothing but the reverse execution of same steps using command/events?

4

Yes, for the processes that need a rollback that is correct. It is recommended to be explicit about that these are compensating actions and use different commands and events.

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5

Sorry for old thread, Please tell me what Unit of Work do in this situation for rollback flow? I read many post but still cannot understand what Unit of Work using for?

6

It’s multiple things, but mainly helpful with making sure when there are multiple actions, either all succeed, or all fail. It depends on how you use compensating actions. For example with a saga, you would likely have something like a TransferFailedEvent. That could be handled in a Saga, which would be in it’s own UnitOfWork.