DDD and implementing persistence

Question

I am getting my feet wet with DDD (in .Net) for the first time, as I am re-architecting some core components of a legacy enterprise application.

Something I want to

Answer 1

Am I correct that the Repository Interfaces live within the Domain assembly, but the Repository Implementations exist within the persistence layer? The persistence layer contains a reference to the Domain layer, never vice versa?

I disagree here, let's say a system is comprised of the following layers:

• Presentation Layer (win forms, web forms, asp.net MVC, WPF, php, qt, java, , ios, android, etc.)
• Business Layer (sometimes called managers or services, logic goes here)
• Resource Access Layer (manually or ORM)
• Resource/Storage (RDBMS, NoSQL, etc.)

The assumption here is that the higher you are the more volatile the layer is (highest being presentation and lowest being resource/storage). It is because of this that you don't want the resource access layer referencing the business layer, it is the other way around! The business layer references the resource access layer, you call DOWN not UP!

You put the interfaces/contracts in their own assembly instead, they have no purpose in the business layer at all.