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

※ Online Lifeline is available in Astah System Safety.

section divider

Adding BaseClass

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

Or, you can create by clicking [New] button from Lifeline’s property view.

Or, you can drag a Class to Sequence diagram to create a lifeline with the class as its base class.

section divider

Show Actor as Lifeline

By dragging an Actor from the tree to diagram, you can represent lifeline in Actor on the Sequence Diagram.
Actor as Lifeline

section divider

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 a diagram and select [Adjust Lifeline Length] and choose from these three options.

Make 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 Maximum
Make all the lifeline to the same length as the longest one on the diagram.
section divider

Minimize Execution Specification

To clean up Sequence diagrams, you can minimize the length of Execution Specifications. Right-click on a diagram and select [Adjust ExecutionSpecification Length].

section divider

Hide Execution Specification

You can hide the Execution Specification box on the Lifeline.
Currently, this is available in Astah Professional, UML, and System Safety editions only.

1. Click anywhere on a diagram.
2. A property view for the Sequence diagram opens in the left-bottom pane. Tick off the [Execution Specification Visibility].

section divider


Found message

To create a found message, select [Synchronous Message] or [Asynchronous Message] from the tool palette and click target Lifeline.
Found Message

Lost Message

To create a Lost message, select [Synchronous Message] or [Asynchronous Message] from the Tool palette and click Lifeline and then anywhere other than Lifeline.
Lost message


To create a gate, select [Synchronous Message] or [Asynchronous Message] from the Tool palette and click on a diagram frame then Lifeline.

Reply Message

There are two ways to create a reply message.
Reply Message in Sequence Diagrams

1. Select [Reply Message] from a tool palette and click a lifeline.
Reply Message

2. Or, turn [Reply Message Mode] on a tool palette and create Messages.
Reply Message

section divider


Combined Fragment


Operand in Sequence diagram

You can create Operand from the CombinedFragment’s Property view or diagram’s pop-up menu.
Combined Fragment

TIPS: Define loop in the CombinedFragment

You can enter texts and numbers from the CombinedFragment’s Property View.