Active Classes

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An Active Class indicates that, when instantiated, the Class controls its own execution. Rather than being invoked or activated by other objects, it can operate standalone and define its own thread of behavior. 

To define an Active Class in Enterprise Architect, follow the steps below:

1.Highlight a Class, and display its Properties dialog.
2.Click on the Advanced button.
3.Select the Is Active checkbox.
4.Click on the OK button to save the details.

OMG UML Specification

The OMG UML specification (UML Superstructure Specification, v2.0, p. 4) states:

"An object that may execute its own behavior without requiring method invocation. This is sometimes referred to as "the object having its own thread of control." The points at which an active object responds to communications from other objects are determined solely by the behavior of the active object and not by the invoking object. This implies that an active object is both autonomous and interactive to some degree."