Getting Started with Domain-Driven Design

Domain-Driven Design (DDD) is not a framework or library. It is a way of thinking about software development that puts the business domain at the center of design decisions.

Sometimes you may hear DDD mentioned alongside frameworks such as Spring, but in reality the concepts of DDD do * not rely on any specific technology*. They are about modeling, communication, and design choices — independent of tools or programming languages.

When done well, DDD helps teams build software that truly reflects the business it serves.

Why Domain-Driven Design?

Many software projects fail not because of technology, but because of a misunderstanding between people who speak different languages about the domain. DDD addresses this by establishing a shared language and aligning code and architecture with business knowledge.

Key benefits:

Shared understanding between developers and domain experts.
Models that evolve with the business, not against it.
A foundation for long-term maintainability.

Core Principles

Ubiquitous Language Create a shared vocabulary with domain experts. Use the same terms in conversations, documentation, and code.
Bounded Contexts Break large systems into smaller, cohesive domains. Each bounded context has its own model and language.
Strategic Design Connect architecture with business strategy. Decide where to invest heavily in modeling and where to keep things simple.
Tactical Design Apply concrete building blocks:
- Entities
- Value Objects
- Aggregates
- Repositories
- Domain Services

When to Apply DDD

DDD makes sense when:

Close collaboration with domain experts is possible.
Long-term maintainability is more important than short-term delivery speed.
The domain is complex and evolving.

When Not to Apply DDD

It’s usually overkill when:

The domain is simple CRUD with few rules. For this case, you probably don't need an application, though.
The project is short-lived and modeling effort won’t pay off — although in many enterprise contexts even a small proof of concept can grow into a long-lived system, so it may still be worth considering some DDD principles early on.

First Steps

Learn the domain language Talk to experts. Document key terms. Use them in your code.
Identify bounded contexts Draw boundaries where models or vocabularies diverge.
Start small Model one slice of the domain. Don’t attempt the entire system at once.
Iterate and refine Treat the model as a living artifact, evolving as you learn.

Example Scenario

Imagine building an online retail system.

The Ordering context deals with carts, checkout, and payments.
The Shipping context deals with packages, carriers, and tracking.

Both contexts are related, but they should not share the same data model. Each evolves independently while integrating where needed.