Summary of "Eric Evans: What I've learned about DDD since the book"

Key Concepts and Insights:

Hands-On Modeling:
Active involvement in projects is crucial for providing valuable advice and staying current in the field. Effective DDD practitioners should engage with real projects to maintain sharpness and relevance.
Collaboration:
Emphasizes the need for creative collaboration between domain experts and software experts. The concept of ubiquitous language is highlighted, which helps in maintaining clear communication across different stakeholders.
Exploration and Experimentation:
Encourages teams to continuously explore and experiment beyond initial models. It's important not to settle for the first useful model but to keep iterating and improving.
Context Mapping:
Evans stresses the significance of defining explicit context boundaries early in the design process. He suggests that context mapping should be a fundamental practice in every project to clarify the relationships and boundaries between different parts of the system.
Core Domain Focus:
Identifying and concentrating on the core domain is essential for maximizing the impact of DDD. This involves understanding how the software can significantly change business situations rather than just making incremental improvements.
Building Blocks:
Discusses various building blocks in DDD, including value objects, entities, and the newly emphasized domain events. Domain events capture significant occurrences within the domain and can enhance clarity and expressiveness in models.
Architectural Implications:
Evans explains how domain events can facilitate decoupling systems, especially in distributed architectures. This allows for independent evolution of systems while maintaining effective communication through event streams.
Aggregate Design:
Aggregates are conceptual wholes that enforce business rules and maintain consistency. He highlights the importance of defining clear boundaries for aggregates to manage complexity and maintain integrity.
Strategic Design:
He identifies three principles of strategic design: context mapping, distillation of the core domain, and large-scale structure. He emphasizes the need for clean bounded contexts and iterative processes to foster successful DDD projects.
Access to Domain Experts:
Evans reiterates that access to domain experts is crucial for effective DDD. Without this access, teams may struggle to create meaningful models and deliver valuable software.

Conclusion:

Evans concludes that DDD is not just about technical implementation but requires a strategic approach, focusing on core domains, context mapping, and collaboration. He emphasizes the importance of maintaining clarity and simplicity in models while allowing for exploration and iteration.