Transition

d_Transition

A Transition defines the logical movement from one State to another, in a State Machine diagram. The Transition can be controlled through the following connector Properties dialog:

TransitionProperties

Option

Use to

Guard

Type in an expression that is evaluated after an Event is dispatched, but before the corresponding Transition is triggered. If the guard is true at that time, the Transition is enabled; otherwise, it is disabled.

Effect is a Behavior

Convert the Effect field from a free-text field to the definition of a specific Activity or behavior.

Enterprise Architect displays the Select <Item> dialog to prompt you to select the Activity or behavior element from the model.

Effect

Either:

  • Type a description of the effect of the Transition, or
  • If you have selected the Effect is a Behavior check box, select an Activity or behavior to be performed during the Transition (to change this subsequently, click on the [ ... ] button to redisplay the Select <Item> dialog).

Trigger

 

Name

Specify the name of the trigger.

Type

Specify the type of trigger: Call, Change, Signal or Time.

  • Call - specifies that the event is a CallEvent, which sends a message to the associated object by invoking an operation.
  • Change - specifies that the event is a ChangeEvent, which indicates that the transition is the result of a change in value of an attribute.
  • Signal - specifies that the event is a SignalEvent, which corresponds to the receipt of an asynchronous signal instance.
  • Time - corresponds to a TimeEvent; which specifies a moment in time.

Note:

Code generation for State Machines currently supports Change and Time trigger events only, and expects a specification value.

Specification

Specify the event instigating the Transition.

Save

Save the current trigger.

Add

Select triggers from the model using the Select Trigger dialog.

Note:

To add multiple triggers, press [Ctrl] while selecting each trigger.

Delete

Remove the selected trigger from the list.

Triggers

List the current triggers for the Transition.

Note:

Fork and Join segments can have neither triggers nor guards.

Toolbox Icon

c_Transition

OMG UML Specification

The OMG UML specification (UML Superstructure Specification, v2.1.1, p. 568) states:

A transition is a directed relationship between a source vertex and a target vertex. It may be part of a compound transition, which takes the state machine from one state configuration to another, representing the complete response of the state machine to an occurrence of an event of a particular type.