I’ve observed a lot of newcomers to the DDD scene, and typically there’s lots of talk about Entities, Value Objects, Aggregate Roots, Repositories, Factories, IoC, and various technical concerns.

But I’m seeing a lot missing from the discussions.  Like “What about the locking implications around an Aggregate?” or “Must Value Objects be immutable“, or even “How do entities retrieve data if they can’t access a repository?“.

To that end, I’ve created a set of interfaces and base classes that represent the building blocks of DDD.  The idea is to get developers thinking about key concepts early in the design process, and let Intellisense provide some guidance.

You can download the source code here.  It has a Ms-Pl licence, so you can modify and use the code as you wish.

The DDD related interfaces are:

  • IDomainObject
  • IEntity
  • IAggregateRoot
  • IValueObject
  • IList<T>
  • IFactory<T>
  • IRepository<T>
  • IService<T>
  • ISpecification<T>
  • IQuerySpecification<TRequestor, TResult>

Additional interfaces for orthogonal concerns are:

  • IPersistable
  • IPersistableList<T>
  • IAudit
  • IAggregateLock
  • IAssertion
  • IDependencyAware
  • IDependencyLocator
  • ITrackable


This is still a work-in-progress, so feedback would be greatly appreciated.  In the next couple of posts, I’ll describe the interfaces and classes.

P.S. The next version of TrueView will be based on these interfaces.  So if you code a domain model using the compiled library, TrueView will auto-generate a completely interactive UI (with the appropriate semantics) directly from your model.