DDD and the ADO.NET Entity Framework

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Introduction to Domain Driven Design

DDD is a structural idea of software creation. The primary thought is that the plan of an application ought to be founded on a model, not on innovation or whatever else. This influences it to clear for designers as well as for professionals in the field.

Domain Driven Design depends on five items:

  1. Entities: These are the articles that speak profoundly of an application. They express the business and are comprehended by customers. What’s more imperative is that every Entity has a personality and it’s special inside the framework.
  2. Value Objects: These items don’t have personalities and depict attributes.
  3. Services: Services contain rationale that doesn’t have a place with a specific Entity.
  4. Factories: This is only a notable example, which deals with making Entities.
  5. Repositories: Repositories are utilized to isolate Entities and their portrayal in a database. They contain code which is in charge of collaboration with a database.

DDD Entities vs. EF EntityObjects

When somebody ponders making another application utilizing DDD and EF, the primary thought which happens is to utilize EF EntityObjects as DDD Entities.

EntityObjects are extraordinary and do have characters, as required for Entities. Be that as it may, they can’t be isolated from the Entity Framework. As per the DDD approach, area items ought to speak to just business rationale, they shouldn’t be in charge of putting away or showing themselves or whatever else. This idea is otherwise called Persistence Ignorance, implying that the area objects are unmindful of how information is spared or recovered from an information source.

Shockingly, EF isn’t a PI ORM, and there is no real way to make EntityObjects autonomous of the system. Their code is auto produced in view of a database outline and a mapping record. Hypothetically, it’s conceivable to make “genuine” substances and utilize the EntityFramework just as an information industriousness layer. Nonetheless, it’s completely strange in light of the fact that for this situation it will be important to again actualize all the industriousness designs gave by EF (Unit of Work, Identity Mapper, and so forth.).

In this way, as far as DDD, the EntityFramework goes about as Repositories and EntityObjects as its incorporated Entities. It is, obviously, a practical arrangement, yet many like to have space objects which don’t know anything about a fundamental information source.

Persistence Ignorance

Persistence Ignorance is something individuals have been contending about for a long time. Some believe it’s great, some believe it’s great however not generally essential.

These are the confinements that a constant insensible structure must not force on the engineer’s area objects:

  • Require acquiring from a predefined base class other than Object
  • Require the utilization of an industrial facility technique to instantiate them
  • Require the utilization of specific information composes for properties, including accumulations
  • Require actualizing specific interfaces
  • Require the utilization of structure particular constructors
  • Require the utilization of particular fields or properties
  • Prohibit particular application builds
  • Require composition RDBMS code, for example, inquiries or Stored Procedure brings in a supplier particular tongue

Regardless of whether it’s decent to have a chance to swap databases, not every person needs it. A more commonsense objective of PI is a capacity to taunt database objects less demanding, which disentangles Unit Testing.


IPOCO remains for Plain Old DLR Object and IPOCO for Interface POCO. POCOs are objects which don’t contain any confounded, system particular code. For instance, EntityObjects in Entity Framework aren’t POCOs, on the grounds that there is a ton of ORM particular code. IPOCO isn’t a real interface, it’s an example which requires actualizing interfaces as opposed to getting from uncommon articles to utilize an ORM.

  • IEntityWithChangeTracker for change following
  • IEntityWithKey for uncovering the substance character key (discretionary, yet not actualizing this interface causes a noteworthy diminishment in execution)
  • IEntityWithRelationships is required for elements with affiliations


If there are constantly different alternatives. You can accomplish a more noteworthy level of reflection for area protests by utilizing IPOCO, by sitting tight for EF v2, or by utilizing another ORM (NHibernate is said to be completely PI).

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