Creating an Interaction

An interaction is used to model how participating communication partners exchange information within a system, by representing the communication partners, the orders and the chronological and logical sequences of messages, and the loops and concurrence of message flows. A sequence diagram describes precisely one non-trivial activity of a Behaviored Classifier.

Prerequisites

In order to be able to create a sequence diagram, you need to specify the Behaviored Classifier for which the information exchange is to be described. Behaviored classifiers include class, component and use case, among others.

Context

You can make the decision as to which behavior is to be described with the sequence diagram in various ways:

Select a behaviored classifier and create an interaction for it.
Create an interaction from the ribbon without selecting, then make the selection in the following dialog. You can select an existing behaviored classifier from the dialog or create a new one.

How to proceed

To describe the communication of an existing behaviored classifier as an interaction, select the class, the component, the use case or the like and select Start>New>New Diagram>Interaction.

The sequence diagram is created and assigned to the behaviored classifier in the model structure as standard. The interaction's owner is shown in the Details tool window.
To describe the communication of an existing BehavioredClassifier – or one that is to be created – as an interaction, select Start>New>New Diagram>Interaction.

A selection dialog appears, prompting you to select a suitable behaviored classifier. Select an existing classifier or use the Create new element button to create a behaviored classifier that doesn't exist yet. In the latter case, a wizard will then take you through the necessary steps.

The sequence diagram is created and assigned to the behaviored classifier in the model structure as standard. The interaction's owner is shown in the Details tool window.

You can now use this diagram for creating communication partners as lifelines and displaying communication between these partners.