Implementing Domain-Driven Design

Publishing Events from the Domain Model

Avoid exposing the domain model to any kind of middleware messaging infrastructure. Those kinds of components live only in the infrastructure. And while the domain model might at times use such infrastructure indirectly, it would never explicitly couple to it. We’ll use an approach that completely avoids the use of infrastructure.

One of the simplest and most effective ways to publish Domain Events without coupling to components outside the domain model is to create a lightweight Observer [Gamma et al.]. For the sake of naming I use Publish-Subscribe, which is acknowledged by [Gamma et al.] as another name for the same pattern. The examples in that pattern and my use of it are lightweight because there ...