Create a Timing Message

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To create a Message in a Timing diagram, at least two Lifeline objects (State or Value) must be created first, each with existing transition points. To create a Message between lifelines, follow the steps below:

1.Click on one of the Lifelines in the Timing diagram.
2.Select the Message icon from the Timing Relationships page of the Enterprise Architect UML Toolbox (More tools | UML | Timing).
3.Drag the cursor onto the Lifeline at the point at which the Message originates. The Timing Message dialog displays. (If not, double-click on the Message):

The dialog consists of a set of transition points. Each transition point can be defined with the following properties:




Defines the lifeline where the message originates.


Defines the lifeline where the message terminates.

These are set by default when a Message is created by dragging the cursor between two Lifelines.



Start Time

Specifies the start time for a message. 

End Time

Specifies the end time for a message.


The name of the message.

Time Observation

Provides information on the time of a sent message.

Duration Observation

Indicates the interval of a Lifeline at a particular state, begun from a message receipt.

Transition To

The state in the target Lifeline that the Message points to.


The occurring event.

Time Constraint

The time taken to transmit a message.

Duration Constraint

Pertains to a lifeline's period at a particular state. The constraint could be instigated by that Lifeline's receipt of a message.

The following diagram shows the Message configured by the above dialog snapshot.


See UML Superstructure Specification, v2.0, figure 351, p. 453; and figure 352, p.454.

Note: You can move the source end of the Message freely along the source timeline. However, the target end (arrow head) must attach to a transition.  If you create a new Message and do not give it a target transition, it automatically finds and attaches to the nearest transition. If you move the target end, it drags the transition with it.