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Destruction Markers

Test RealTime - User Guide

Destruction Markers

A destruction marker (also known as a termination symbol) is a notation that can
appear on a lifeline to indicate that an instance (object or classifier role) has been
destroyed. Usually, the destruction of an object results in the memory occupied by
the data members of the object being freed.

For example, when a customer exits the Web site for an e-commerce application, the
":Cart" object that held information about the customer's activities is destroyed, and
the memory that it used is freed. The destruction of the ":Cart" object can be shown in
a sequence diagram by adding a destruction marker on the ":Cart" object's lifeline.

Shape

A destruction marker appears as an X at the end of a lifeline.

Naming Conventions

Destruction markers do not have names.

Lifelines

A lifeline is a notation that represents the existence of an object or classifier role over
a period of time. Lifelines appear only in sequence diagrams, where they show how
each instance (object or classifier role) participates in the interaction.

For example, a "Place Online Order" interaction in an e-commerce application
includes a number of lifelines in a sequence diagram, including lifelines for a ":Cart"
object, ":OnlineOrder" object, and ":CheckoutCart" object. As the interaction is
developed, stimuli are added between the lifelines.

Shape

A lifeline appears as a vertical dashed line in a sequence diagram.

Lifeline for an

Object

Lifeline for a

Classifier Role