Advancing Enterprise DDD - Entities, Value Objects, and Identity

In the previous essay of the Advancing Enterprise DDD series, we saw how we might improve our Domain Driven Design model by making our entity classes immutable. Here, we continue to investigate immutable entities by seeing how this affects one of the core DDD building blocks: the value object.

Advancing Enterprise DDD - Migrating to Immutability

In the previous essay of the Advancing Enterprise DDD series, we saw difficulties emerge in maintaining intra-aggregate constraints. These difficulties arose due to the mutability of our entities, and the Java collections they use to maintain relationships between entities. We also saw that it would be difficult or impossible to use immutable alternatives within JPA. In this essay, we set aside the constraints of JPA for a moment, and imagine a world where entities are composed of immutable objects.

Advancing Enterprise DDD - Maintaining Intra-aggregate Constraints

In this essay of the Advancing Enterprise DDD series, we begin look to at immutable objects - a common point of contrast between functional and object-oriented programming approaches. In the last essay, we saw at how MongoDB would be a much better vehicle than RDB for persisting well-shaped DDD aggregates. In this essay, we continue to investigate at the way the tools we use affect our thinking and coding, as we witness the contortions we have to go through to make something as straightforward as an intra-aggregate constraint work in the face of mutability.