Domain Driven Design

Domain-Driven Design is a collection of principles and patterns for mapping business domain concepts into software artifacts.

This mapping provides an easy understanding of the business requirements, data entities, and process models.
The derived model is modular, extensible, and easy to maintain as the design reflects the business model.
It improves the reusability and testability of the business domain objects.

Characteristics of a Rich Domain Model

The domain model should focus on a specific business operational domain. It should align with the business model, strategies, and business processes.
It should be isolated from other domains in the business as well as other layers in the application architecture.
It should be reusable to avoid any duplicate models and implementations of the same core business domain elements.
The model should be designed loosely coupled with other layers in the application, meaning no dependencies on the layers on either side of domain layer.
It should be an abstract and cleanly separated layer enabling easier maintenance, testing, and versioning. The domain classes should be unit testable outside the container.
The domain model should be independent of persistence implementation details.