Domain Driven Design, .NET and the Entity Framework

Question

I'm new to domain driven design but want to learn it and use it for a new application. I will be using Entity Framework for data access.

The basic layout so far is:

ASP.NET MVC and other clients (mobile devices etc.)
|
Webservices
|
Domain Model (Services, Repositories, Aggregates, Entities and Value Objects)
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Data Access Layer (Entity Framework)
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Data Storage (SQL Server)

What is the best way to transfer data between the data access layer and the domain model? I'm thinking that the entities in the domain model are POCO objects and that they should be mapped to/from the Entity Framework objects. Is this a good solution?

If so:
How and where should such a mapping occur? (Domain Model Layer or Data Access Layer)
Where and how should I query Entity Framework (ie. return a list based on a search)?

Answer 1

I'm thinking that the entities in the domain model are POCO objects and that they should be mapped to/from the Entity Framework objects. Is this a good solution?

I think it is.

This is something that we have done quite successfully, although in my case in the Java world. Our domain classes contain the majority of the business logic. Each has a reference to a thin data entity object and delegates the getting and setting of the persistent properties to the data entity.

Answer 2

The S#arp architecture project is an excellent starting point for guidance on applying DDD. It is based on NHibernate, but the principles used should hold equally for EF...

Answer 3

I would go for Enterprise Core Objects (ECO) from capableobjects.com

It does everything you would ever want from a DDD framework

Answer 4

ANDREY YEMELYANOV has done a masters thesis on this exact subject:

http://gupea.ub.gu.se/dspace/bitstream/2077/10462/1/gupea_2077_10462_1.pdf

This will get much easier with the release of EF 4, which supports POCO objects.

In the meantime you could try using automapper to map between domain and EF objects, see: http://www.lostechies.com/blogs/jimmy_bogard/archive/2009/01/22/automapper-the-object-object-mapper.aspx