Define Domain Concepts

Domain-driven Design (DDD) is all about identifying and naming domain concepts and translating them as closely as possible - terminology, structure, and behavior - in code. Protean supports the tactical patterns outlined by DDD to mirror the domain model in code model.

In this section, we will talk about the foundational structures that make up the domain model. In the next, we will explore how to define behavior and set up invariants (business rules) that bring the Domain model to life.

Domain Layer

One of the most important building block of a domain model is the Aggregate. Aggregates are fundamental, coarse-grained building blocks of a domain model. They are conceptual wholes - they enclose all behaviors and data of a distinct domain concept. Aggregates are often composed of one or more Aggregate Elements, that work together to codify the concept.

In a sense, Aggregates act as Root Entities - they manage the lifecycle of all Entities and Value Objects enclosed within them. All elements enclosed within an Aggregate are only accessible through the Aggregate itself - it acts as a consistency boundary and protects data sanctity within the cluster.

Read more about Aggregates in Building Blocks.

Entities Value Objects Domain Services Events

Application Layer

Application Services Subscribers

Infrastructure

Persistence

Repositories Models Read Models Caches

Communication

Brokers

Architecture Patterns

CQRS Event Sourcing