You can create UML Sequence diagrams.
UML Sequence Diagram Sample

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Diagram Properties

You can set diagram properties, such as visibility settings, in the Property view (bottom-left pane).
Sequence diagram Property view

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Automatic Diagram Layout

Since version 8.5 of Astah Professional and Astah UML, automatic diagram layout is available.

To use the auto-layout, go to [Alignment] – [Auto Layout] – [Vertical / Horizontal].

However, this auto-layout does not work for CombinedFragments. You will need to reposition CombinedFragments manually, so the [Gap Expander] and [Gap Remover] options may work better if your Sequence diagram contains several CombinedFragments.

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Lifeline

You can create a lifeline by double-clicking on a diagram, or by choosing it from the tool palette and clicking on the diagram.
UML Sequence Diagram Lifeline

Since version 9.2, you can create a Lifeline by dragging a Component from the tree view and dropping it on the diagram.
Create a Lifeline by drag and drop of Component

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Adding a BaseClass

There are three ways to add a base class to a Lifeline.

1. Directly type in a Lifeline

You can add a base class to a Lifeline by directly typing its Class (Block) name after the Lifeline name.

2. From Lifeline’s property view

  1. Select a Lifeline.
  2. Go to the property view (bottom-left pane) and click the [New] button.
    Adding a base class to a Lifeline

  3. A pop-up appears where you can specify a class.

3. Drag a Class to Lifeline

You can drag a Class onto a Sequence diagram to create a lifeline with the class as its base class.

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Show Actor as Lifeline

By dragging an Actor from the tree onto the diagram, you can show a Lifeline as an Actor on the Sequence Diagram.
Actor as Lifeline

Actor as a Lifeline

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Adjust Lifeline length

After creating a Sequence diagram, you may want to adjust the length of Lifelines to clean up the diagram. Right-click on the diagram, then select [Adjust Lifeline Length] and choose from these three options.
Changing Lifeline Length on Sequence Diagram

Options

DefaultMake all the lifeline to the shortest possible.
Align to Minimum
Make all the lifeline to the same length as the shortest one on the diagram.
Align to MaximumMake all the lifeline to the same length as the longest one on the diagram.
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ExecutionSpecification

Minimize Execution Specification’s length

To clean up Sequence diagrams, you can minimize the length of Execution Specifications.

Right-click on the diagram, then select [Adjust ExecutionSpecification Length].
Adjusting Execution Specification lengths on Sequence Diagram

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Hide Execution Specification

You can hide Execution Specifications. This is available in Astah Professional, UML, and System Safety editions only.
Hiding Execution Specification on Lifelines

  1. Click anywhere on a diagram.
  2. A property view for the Sequence diagram opens in the bottom-left pane.
  3. Uncheck [Execution Specification Visibility].
    Hiding execution specification on Lifelines
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Message

Found Message

You can create a Found message.

  1. Select [Synchronous Message] or [Asynchronous Message] from the tool palette.
  2. Click on the diagram.
  3. Click on a target lifeline.
    Found Message

Lost Message

You can create a Lost Message.

  1. Select [Synchronous Message] or [Asynchronous Message] from the Tool palette.
  2. Click the Lifeline that you want to be the origin of the Message.
  3. Click on a diagram.
    Lost message

Gate

You can create a Gate.

  1. Select [Synchronous Message] or [Asynchronous Message] from the Tool palette.
  2. Click on the diagram frame.
  3. Click a Lifeline.
    Gate

Reply Message

There are two ways to create Reply Messages.
Reply Message in Sequence Diagrams

Create manually

  1. Select [Reply Message] from the tool palette.
    Reply Message
  2. Click the ExecutionSpecification that you want to be the origin of the Reply Message.

Create Automatically

  1. Turn on [Reply Message Mode] in the tool palette.
    Reply Message Automatic Mode

  2. Create a Message.
  3. A Reply Message is generated automatically.
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CombinedFragment

You can create CombinedFragments.

  1. Select [CombinedFragment] from the tool palette.
  2. Specify the area where you want to create CombinedFragment. The area should include at least one Lifeline.


Add an Operand

There are two ways to add Operands to CombinedFragments.

Create from pop-up menu

  1. Right-click on a CombinedFragment.
  2. Select [Add operand].
    Add operands

Create from Property View

  1. Select a CombinedFragment on the diagram.
  2. Go to the property view (bottom pane) and choose the [Operand] tab.
  3. Click the [Add] button to add operands.
    Add Operands to CombinedFragments

    CombinedFragment with operands

TIPS: Define loop in the CombinedFragment

You can enter loop conditions (text and numbers) in the CombinedFragment’s Property View.
Loop settings in the CombinedFragment Property View

Loop settings in the CombinedFragment Property View

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InteractionUse

You can create InteractionUse.

  1. Select [InteractionUse] on a tool palette.
  2. Drag to specify where you want to place the InteractionUse.

You can create InteractionUse within a CombinedFragment as well.
InteractionUse within a CombinedFragment

Auto-generate Sequence Diagrams

Starting from version 11, Astah Professional and Astah UML can automatically generate Sequence diagrams from source code with AI Code Reverse. For details, see the AI Code Reverse page.