How to Divide the Bounded Context?
Overview
This document summarizes ways to divide the Bounded Context.
Introduction
A Bounded Context is a clearly defined boundary that uses specific terms with precise meanings. In other words, it is an explicit boundary within which the domain model applies and maintains consistency.
Within each context, terms have their own distinct meaning. Therefore, the objects in a bounded context are more cohesive and explicit.
Well-divided contexts can increase development productivity and become a standard for good design. This document explains methods for dividing bounded contexts effectively.
How to Divide the Bounded Context
In Domain-Driven Design (DDD), there is no single definitive standard for dividing a bounded context. Instead, multiple factors should be considered.
Ubiquitous Language
Ubiquitous Language is the most common criterion for division. If the same term is used with different meanings, it is a signal to separate into different contexts.
For example, the term “Order” may mean different things in the Marketing domain, Delivery domain, and Accounting domain — these should be treated as different contexts.
Business Function or Process
Bounded contexts can be divided by business processes.
For example, the process of canceling an order belongs to the Order domain.
Independent Model & Data Ownership
Each context should have its own domain model and data storage. One context should not directly reference another’s data; interaction should happen through an API gateway or events.
Correspond with Team Boundary or Structure
According to Conway’s Law, team structures influence system architecture. Dividing contexts based on team boundaries can increase cohesion and reduce coupling.
Domain Event and Flow Analysis
Analyzing events can reveal dependency flows between contexts. If an event triggers work that uses a different model, the contexts should be separated.
Policy and Rule-Based Separation
If different rules apply in different areas, those areas should be separate contexts.
Context Map
When dividing contexts is difficult, you can use a Context Map as a tool.
A context map visualizes communication, integration, dependency separation, and relationships between bounded contexts.
You can create a context map using tools such as PlantUML + Context Map DSL, Structurizr, or Draw.io / Lucidchart.
Final Thoughts
Bounded Context is a key concept for effectively applying DDD, and knowing how to divide it is even more important. I have learned ways to divide bounded contexts and understood the value of context maps.
If you need to create a context map with your team, this article can serve as a useful reference.