How do you document your domain model?

1 Use a common language

One of the key principles of domain-driven design (DDD) is to use a ubiquitous language that is shared by the domain experts, developers, and other stakeholders. This language should be reflected in your domain model documentation, using the same terms, definitions, and examples that are used in the domain. Avoid using jargon, acronyms, or technical details that are not relevant or understood by the domain. Use diagrams, tables, or code snippets to illustrate your domain model, but make sure they are consistent with the ubiquitous language and the written descriptions.

2 Focus on the core concepts

A domain model is not a complete specification of every aspect of the domain. It is a simplified and abstracted view of the core concepts that are essential for solving the domain's problems. Therefore, your domain model documentation should focus on the core concepts and their relationships, and avoid including unnecessary or irrelevant details. Identify the key entities, value objects, aggregates, services, and events that make up your domain model, and document their properties, behaviors, and invariants. Explain the domain rules and constraints that govern your domain model, and how they are enforced or verified. Use examples and scenarios to demonstrate how your domain model works in different situations.

3 Organize your documentation

A domain model can be complex and large, especially if it spans multiple subdomains or bounded contexts. To make your domain model documentation easier to read, navigate, and maintain, you should organize it in a logical and consistent way. Use a hierarchical structure that groups related concepts together, and separates different subdomains or bounded contexts. Use cross-references and links to connect different parts of your documentation, and provide a glossary or index for quick access to terms and definitions. Use a standard format and style for your documentation, and follow the conventions and guidelines of your organization or project.

4 Update your documentation

A domain model is not static. It evolves over time as you learn more about the domain, discover new requirements, or refactor your design. Your domain model documentation should reflect these changes and keep up with the current state of your domain model. Update your documentation whenever you make significant changes to your domain model, and review it regularly to ensure its accuracy and relevance. Use version control, change logs, or other tools to track and manage your documentation changes, and communicate them to your team and stakeholders. Solicit feedback and suggestions from your domain experts, developers, and other readers to improve your documentation quality and usefulness.

5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?