What is a Bounded Context?

In Domain-Driven Design (DDD), a Bounded Context is a central concept that helps in managing complexity within a large system. It defines a clear boundary within which a particular domain model is defined and applicable. Within this boundary, a specific domain or subdomain’s concepts, rules, and logic are consistent and well understood.

Key aspects of Bounded Context:

Boundary of Consistency: Inside a bounded context, terms, rules, and operations have specific meanings. Outside this boundary, similar terms or operations might have different meanings. This ensures clarity and reduces ambiguity.

For example, in a Sales bounded context, the term "Order" might mean something specific (like a customer purchase), while in a Logistics bounded context, "Order" might refer to a shipment.

Separation of Models: In large systems, different parts of the system may have different models that are optimized for their specific needs. A bounded context allows these models to be developed and evolve independently, without forcing a single, global model that can become overly complex.

Communication Between Contexts: Since each bounded context is self-contained, there is often a need to communicate or integrate between them. This is typically done through well-defined interfaces, APIs, or translation layers. This interaction is carefully managed to avoid mixing the models and their meanings.

Ubiquitous Language within the Context: Inside a bounded context, the team uses a shared language (ubiquitous language) that is understood by both developers and domain experts. This language aligns with the business domain and helps bridge the gap between technical and non-technical team members.