Interesting. Using composition of objects like that is a sensible enough approach. What about also just implementing lazy loading in your domain objects. If you try to get details of a user and it's already been fetched from the server, then great. If not then fetch it from the server. I guess that's what you're doing in a way, but with lazy loading, the fetching logic would be tied to the entity class and the rest of the application doesn't need to care.