What constitutes a rich domain model in a POJO/POCO?
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10-07-2019 - |
Question
What is the difference between
- A simple fields-accesors-mutators class
- A rich-modeled class
What constitutes rich modeling in business-domain classes?
Solution
"Rich" as used here implies "rich behavior" (as opposed to state).
There is technical behavior and domain behavior. Accessors and mutators are technical; they lack the "why" which defines business interest.
Domain objects represent the "why" and encapsulate the "how". Actually, all objects do that; domain objects do it specifically for business value.
Let's say you, as an employee domain object, have to request a day off of work. You have 2 options:
- Tell your manager and he marks the schedule.
- Ask your manager for the schedule and mark it.
Model 1 is rich. The "why" (vacation time) encapsulates the "how" (marking the schedule).
Model 2 relegates the manager to a simple property bag and leaks the scheduling abstraction.
OTHER TIPS
When your business logic is encapsulated in your business objects. In other words, you have a Business Objects (Domain Model) layer, without the need for a separate Business Logic layer.