Let’s draw the following sequence diagram. This sequence diagram is based on “Figure D.10 – White Box Interaction for “StartVehicle” (Sequence Diagram)” in the SysML 1.5 specification, with a bit of additional objects.

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Sequence Diagram

  1. If you are starting the tutorial from this page, you can download Astah SysML and a sample file which contains all the diagrams throughout the previous chapters.
  2. Right-click on a “HSUV” block in the structure tree.
  3. Then select [Create Diagram] – [Sequence Diagram] from the pop-up menu.
  4. Then a blank Sequence Diagram will open in the diagram editor.
  5. Rename the sequence diagram to “StartVehicleWhiteBox” in the structure tree or in the properties view of the Sequence diagram.

Actually, you can draw a similar process flow in Sequence diagrams, but the Sequence diagram shows the message exchange between Objects in chronological order.

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Let’s create Lifelines.

  1. Drag and drop the “ElectricalPowerController” Block from the tree view to diagram
  2. Then a Lifeline with the block type will be created.

In this tutorial, we will omit the object names, as there is no particular distinction between objects.
Let’s create another Lifeline with “PowerControlUnit” Block in the same way.

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Asynchronous message

Let’s create Messages.
In the sample diagram, the message from the frame to the “PowerControlUnit” object is an asynchronous messages.

  1. Click the fourth button from the left in the tool palette to create the asynchronous message.
  2. Click on the frame and then on the “PowerControlUnit” lifeline. to draw the message arrow.
  3. Rename it to “StartVehicle()”.
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Synchronous Message

Let’s create a synchronous message.
This is a message from the “PowerControlUnit” to the “ElectricalPowerController”.

  1. Click the third button from the left in the tool palette
  2. Click on the bar on the “PowerControlUnit” then click on the lifeline of “ElectricalPowerController”.
  3. Then the message will be created.
  4. Add “enable” for the message name.
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Reply Message

  1. Clickthe seventh button from the left in the tool palette
  2. Click on the “ElectricalPowerController” ExecutionSpecification then rename it to “ready”.
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Interaction Use

  1. Select the “InteractionUse” tool button.

  2. Drag the area you want to place the InteractionUse from the left to right covering the target lifelines.
  3. Then set the name as “Park/ShutdownVehicle”.

Now you have nailed the Sequence Diagram!
You can also download the file that contains this Sequence Diagram from here.