Best Practices for Domain-Driven Design (DDD)

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Best Practices for Domain-Driven Design (DDD)

  • As part of the “Best Practices” series by Uplatz

 

Welcome to another edition of the Uplatz Best Practices series — your guide to architecting purposeful, scalable, and maintainable systems.
 Today’s focus: Domain-Driven Design (DDD) — a powerful approach to modeling complex software systems around real business logic.

🧱 What is Domain-Driven Design?

Domain-Driven Design (DDD) is a strategic and tactical software development methodology introduced by Eric Evans. It emphasizes building software that reflects the structure and language of the business domain.

DDD encourages:

  • Close collaboration between technical teams and domain experts

  • Bounded contexts to organize complex systems

  • Ubiquitous language to align communication across stakeholders

  • Modeling the business domain as the core focus of software architecture

DDD is especially useful in large, evolving systems where technical complexity mirrors business complexity.

✅ Best Practices for Domain-Driven Design

DDD is not just about code — it’s about aligning architecture with the business. Here’s how to implement DDD effectively in your organization:

1. Understand the Domain Deeply

🧠 Collaborate with Domain Experts Continuously – Software design is a shared language.
 🎯 Capture Business Rules Explicitly – Embed them in code, not just documents.
 🔍 Ask Why, Not Just What – Understand business intent behind every requirement.

2. Use a Ubiquitous Language

💬 Create a Shared Vocabulary – Everyone (devs, PMs, stakeholders) uses the same terms.
 📘 Reflect That Language in Code – Method names, class names, events, etc.
 🔁 Evolve Language as the Domain Evolves – Language is a living artifact.

3. Define Bounded Contexts Clearly

🧱 Split Complex Systems into Logical Domains – Each with its own models and language.
 🚪 Avoid Leaky Abstractions Across Contexts – Interfaces should hide internal implementation.
 📐 Use Context Maps – To define relationships (e.g., upstream/downstream, anti-corruption layers).

4. Model the Core Domain First

🏦 Focus on What Differentiates the Business – Build rich models for critical areas.
 🪆 Defer Complexity in Generic Domains – Don’t over-engineer supporting features.
 🔁 Iterate Models with Stakeholders – Constantly refine and improve.

5. Apply Strategic Design

📊 Use Core, Supporting, and Generic Subdomains – Allocate resources accordingly.
 🛡 Use Anti-Corruption Layers (ACLs) – When integrating across contexts or legacy systems.
 🤝 Define Clear Contracts Between Teams/Services – Based on bounded contexts.

6. Design Aggregates Carefully

📦 Each Aggregate = Consistency Boundary – A cluster of domain objects with one root.
 🔒 Keep Aggregates Small – For better performance and reasoning.
 🔁 Handle Transactions Within a Single Aggregate – Avoid cross-aggregate consistency issues.

7. Use Domain Events

📣 Model Business Events Explicitly – OrderPlaced, PaymentReceived, etc.
 🧩 Enable Event-Driven Integration – Between bounded contexts or microservices.
 🔁 Track Changes in State, Not Just CRUD – Events reflect intent and history.

8. Keep the Domain Model Pure

🧼 Separate Infrastructure Concerns – Keep persistence, transport, and logic separate.
 🧪 Write Business Logic That’s Easy to Test – No side effects, minimal dependencies.
 🚫 Avoid Anemic Models – Logic should live inside domain entities, not outside them.

9. Embrace Tactical Design Patterns

🔀 Use Entities, Value Objects, Repositories, Services – Follow DDD tactical patterns.
 📐 Apply Specification Pattern for Queries – Keep repositories simple.
 🔁 Encapsulate Workflows with Domain Services – For behavior not tied to a single entity.

10. Evolve the Model Over Time

🔄 Use Event Storming or Domain Crunching – To discover new insights.
 🧭 Refactor Without Fear – A good domain model should grow with your understanding.
 📈 Let the Business Drive Refactoring – Model changes should reflect domain shifts.

💡 Bonus Tip by Uplatz

Domain-Driven Design is not about complexity — it’s about clarity.
 The goal is to make the software model the business, so the business can trust the software.

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