Describe System Behavior Using Sequence Diagrams

You can use sequence diagrams integrated with System Composer™ to describe system behaviors as the interaction between components in a sequence of message exchanges. When you create interactions and author sequence diagrams, you can:

• Represent instances of components as participants of an interaction using lifelines.

• Represent communication between lifelines using messages. Use message labels to describe the how lifelines should interact with each other.

• Describe the exchange of messages between an architecture and its environment using gates.

• Group messages and implement more complex semantics like conditionals or looping using fragments and operands.

• Co-create components, ports, and connections in your architecture model as you create new lifelines and messages.

• Iteratively check consistency between your architecture and the corresponding sequence diagrams.

• Represent interactions between service components using call and response messages. For more information, see Describe Client-Server Interactions Using Sequence Diagrams.

To read more about concepts relevant to authoring sequence diagrams, see Specify Operational Constraints Between Components Using Executable Sequence Diagrams.

Create New Sequence Diagram

To create a sequence diagram in the Architecture Views Gallery, use one of these three methods:

• From the toolstrip, click Modeling > Sequence Diagram.

  1. To create a new sequence diagram, click New > Sequence Diagram.

  2. A new sequence diagram called SequenceDiagram1 is created in the View Browser, and the Sequence Diagram tab becomes active. Under Sequence Diagram Properties, you can rename the sequence diagram.

• To create a sequence diagram programmatically, use the addInteraction function to create a new sequence diagram. For more information, see Create Sequence Diagrams Programmatically.

• From the Architecture Views Gallery, right-click a view and select New Sequence Diagram.

  A new sequence diagram of lifelines is created with all components from the view.

Author, Simulate, and Validate Sequence Diagrams

Sequence diagrams are integrated with architecture models in System Composer. While designing your system, use sequence diagrams as a planning tool to envision the behavior of your system. You can iteratively simulate your sequence diagrams to validate an expected sequence of events as you develop your system design.

Topic	Description
Author Sequence Diagrams Interactively	Interactively create and edit sequence diagrams.
Model Complex Interactions Using Fragments in Sequence Diagrams	Implement different types of fragments.
Create Sequence Diagrams Programmatically	Programmatically create and edit sequence diagrams.
Author Architecture Models Through Sequence Diagrams	Co-create and synchronize to maintain consistency between sequence diagrams and architectures.
Simulate Sequence Diagrams for Traffic Light Example	Simulate interactions to verify system behavior.

Tip

To learn more about how System Composer concepts apply to systems engineering design, see System Composer Concepts.