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Using Activations

Test RealTime - User Guide

Using Activations

Activations can appear on your sequence diagrams to represent the following:

On lifelines depicting instances (actors, classifier roles, or objects), an activation
typically appears as the result of a message to indicate the time during which an
instance is active.

On lifelines involved in complex interactions, nested activations (also known as
stacked activations or nested focuses of control) are displayed to indicate nested
stack frames in a calling sequence, such as those that happen during recursive
calls.

On lifelines depicting concurrent operations, the entire lifeline may appear as an
activation (thin rectangles) instead of dashed lines.

Naming Conventions

An activation is usually identified by the incoming message that initiates it.
However, you may add text labels that identify activations either next to the
activation or in the left margin of the diagram.

Classifier Roles

A classifier role is a model element that describes a specific role played by a classifier
participating in a collaboration without specifying an exact instance of a classifier. A
classifier role is neither a class nor an object. Instead, it is a model element that
specifies the kind of object that must ultimately fulfill the role in the collaboration.
The classifier role limits the kinds of classifier that can be used in the role by
referencing a base classifier. This reference identifies the operations and attributes
that an instance of a classifier will need in order to fulfill its responsibilities in the
collaboration.

Classifier roles are commonly used in collaborations that represent patterns. For
example, a subject-observer pattern may be used in a system. One classifier role
would represent the subject, and one would represent the observer. Each role would
reference a base class that identifies the attributes and operations that are needed to
participate in the subject-observer collaboration. When you use the pattern in the
system, any class that has the specified operations and behaviors can fill the role.

Shape

A classifier role appears as a rectangle. Its name is prefixed with a slash and is not
underlined. In sequence diagrams, a lifeline (a dashed, vertical line) is attached to the
bottom of a classifier role to represent its life over a period of time. For details about
lifelines, see Lifelines.

Classifier Role

with Lifeline