UML Sequence Diagrams

About the UML Sequence Diagram

A UML sequence diagram provides insight and an overview of object interactions arranged in a time sequence. It shows the objects and classes involved in a scenario and a sequence of messages exchanged between objects needed to perform functionality.

When to Draw a UML Sequence Diagram?

A UML sequence diagram shows the scenario (flow of events) in one single use case. The flow of messages in the sequence diagram is based on the story told by a use case.

If you want to draw a sequence diagram, you normally need to draw a use case diagram and describe what the use case in question does.

The Elements of a Sequence Diagram

A sequence diagram consists of elements:

• Lifeline Notations
• Activation Bars
• Message Arrows

Below you see three examples of these elements:

UML Lifeline notation with an Actor symbol

UML Activation bar

UML Message Arrows

Model your UML diagram on the Dragon1 Platform

Dragon1 is fit for purpose for UML modeling. Create your trial account and start creating UML Use Case diagrams and models right away: www.dragon1.com/help/create-use-case-diagram