Allow outbox to be enabled for send only endpoints via an explicit opt-in setting

[andreasohlund]

Allows Particular/NServiceBus.TransactionalSession#96 to be implemented in the future.

[andreasohlund]

@danielmarbach should we enable sagas as well? https://github.com/Particular/NServiceBus/blob/master/src/NServiceBus.Core/Sagas/Sagas.cs#L33

The more I think about this I feel that both the outbox and sagas should depend on the storage session being enabled and that one in turn should look at send only or not?

[danielmarbach]

As far as I recall, synchronized storage is always enabled when either outbox or saga are activated because it is required to setup the DI part too.

should we enable sagas as well?

I see no benefit for a sendonly endpoint to do that. You?

[andreasohlund]

I see no benefit for a sendonly endpoint to do that. You?

Yea, since you need to receive messages (currently) in order to interact with sagas

[andreasohlund]

I've verified that this works for SQLP by adding the override and seeing that a send only endpoint is able to get data into the outbox table

[DavidBoike]

Given I just fixed the Audit behavior for send-only endpoints in #6740, are there any knock-on effects to having the Outbox run in https://github.com/Particular/NServiceBus/blob/master/src/NServiceBus.Core/Audit/Audit.cs#L19-L20 that should be considered? The endpoint is still send-only, not receiving messages, and therefore not creating an audit queue, so all is good, right?

[andreasohlund]

The endpoint is still send-only, not receiving messages, and therefore not creating an audit queue, so all is good, right?

Yea

[danielmarbach]

😎👍Awesome