Question: How to publish an outbox-using distributed event that is compatible with the local event bus provider.

[gdlcf88]

Assume I am deleting a Book entity, and I want to send a notification email to the author if the deletion success.

After #10008, using the distributed event bus with outbox may be a good way since it ensures the UOW completion success and then publishes the domain events. When the IDistributedEventHandler<EntityDeletedEto<BookEto>> executes, the book entity must have been deleted.

But the question is, I noticed that the LocalDistributedEventBus does not handle the param useOutbox = true:

abp/framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Distributed/LocalDistributedEventBus.cs

Lines 136 to 144 in e3e1779

	public Task PublishAsync<TEvent>(TEvent eventData, bool onUnitOfWorkComplete = true, bool useOutbox = true) where TEvent : class
	{
	return _localEventBus.PublishAsync(eventData, onUnitOfWorkComplete);
	}
	public Task PublishAsync(Type eventType, object eventData, bool onUnitOfWorkComplete = true, bool useOutbox = true)
	{
	return _localEventBus.PublishAsync(eventType, eventData, onUnitOfWorkComplete);
	}

This presents a problem because it invokes the handlers as a local event before the UOW saves changes. The book has not been deleted or even will fail to delete.

If the above business is in a module, I don't know whether the app developers are using a real distributed event bus provider or not. So what should I do as a module developer? Or, is there any deviation in my understanding of this design?

Thanks.

:)

[maliming]

The local handler is run on the same UOW and will publish onUnitOfWorkComplete.

[gdlcf88]

Take the above example IDistributedEventHandler<EntityDeletedEto<BookEto>>.

If I send the email in this event handler (after ABP 5.0), I cannot ensure that the DB transaction commits success (since the app developers may use the LocalDistributedEventBus).

[gdlcf88]

Thank you @maliming for eae8d63.

The local distributed event bus has the same behavior now:

[jortygu]

@maliming commit:eae8d63 canceled? latest code don't contain commit content.

[maliming]

hi @jortygu

#12385 (comment)

[jortygu]

@maliming is there any chance use outbox pattern in local event，i want to save data and event in same transaction and then trigger event by background worker (with retry system)，i don't want to use real distributed event bus.