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Reading a DDD document I was left with doubt about the following paragraph, in the highlighted part.
"...the layers (interface, Application, Domain and infrastructure) must be disassociated from each other always communicating through interfaces and the bottom layer never fire operations on the top layer..."
How this would apply in the case of asynchronous events where, for example, the infrastructure layer should inform the application/interface layer that some process has been completed, or the domain/application layers themselves, informing to the interface layer of the same?
Since an async event (Node for example) is disconnected, the callback result is inside the same layer and not in the previous layer. I agree that if the process is synchronous it follows the return path, but in the async it (almost always) is fired within the context of its execution.
Was the doubt clear? I appreciate any document link and/ or code that demonstrates this concept.