The Repository pattern from Domain Driven Design is one of the cleanest ways I have come across for separating our domain objects from their persistence mechanism.

Until recently every single implementation I had seen of this pattern involved directly using a database as the persistence mechanism with the repository acting as a wrapper around the Object Relational Mapper (Hibernate/NHibernate).

Now I consider there to be two parts to the repository pattern:

This pattern can also be useful when we retrieve and store data via services which we have been doing recently. Of course eventually the data is stored in a database but much further up stream.

To start with we were doing that directly from our controllers but it became clear that although we weren’t interacting directly with a database the repository pattern would still probably be applicable.

The way we use it is pretty much the same as you would if it was abstracting an ORM:

I think with an ORM the mapping would be done before you got the data back so that’s an implementation detail that is slightly different but as far as I can see the concept is the same.