Unitentity

Unitentity is a term used in software engineering to describe a minimal, self-contained representation of a thing within a domain model. It fuses the idea of a unit (the smallest addressable piece) with an entity (an object with a distinct identity) to form a discrete, durable unit of data and behavior that can be managed within a system.

Typically, a unitentity includes a unique identifier, a mutable state representing its properties, and a set of operations or behaviors that enforce business rules. In many designs, a unitentity is persisted in storage and participates in business processes through domain services or application services. It may be composed of simple value fields or linked to other unitentities via relationships.

Use cases include domain-driven design, event-sourced architectures, and entity-component-system patterns in game development, where each unitentity represents a concrete concept such as a customer, product, or game unit. An example: a UnitEntity Soldier with fields id, health, position, and methods move and takeDamage.

Relation to other concepts: unitentity is a type of entity distinguished by its unit-sized scope; it is not the same as a value object, which lacks identity, nor is it strictly the same as an aggregate root. Depending on context, the term may be used variably, and some teams reserve it for components that combine data with invariants and behavior.

See also: entity, value object, aggregate, domain-driven design, entity-component-system.