Classifier (UML)

A classifier is a category of Unified Modeling Language (UML) elements that have some common features, such as attributes or methods.

Overview
A classifier is an abstract metaclass classification concept that serves as a mechanism to show interfaces, classes, datatypes and components.

A classifier describes a set of instances that have common behavioral and structural features (operations and attributes, respectively).

A classifier is a namespace whose members can specify a generalization hierarchy by referencing its general classifiers.

A classifier is a type and can own generalizations, thereby making it possible to define generalization relationships to other classifiers.

A classifier is a redefinable element, as it is possible to redefine nested classifiers.

All objects that can have instances are classifiers.

Important aspects

 * A classifier defines a namespace.
 * A classifier contains a set of features.
 * A classifier is generalizable.

Types of UML classifiers

 * Class
 * Component
 * Datatype
 * Interface
 * Node
 * Signal
 * Subsystem
 * Use Case

Predefined UML classifiers

 * Actor
 * Association
 * Class
 * Component
 * Datatype
 * Interface
 * Node
 * Signal
 * Subsystem
 * Use Case