An operation is an external prompt, represented by an interface,
that attempts to trigger a movement from one state to another.
To add an operation to an existing transition, proceed as follows:
- On the canvas, select and hover over the transition
that you want to modify.
- In the action bar that appears, click the operation icon as shown
in this image.

- In the Properties area, configure the settings in the Description tab
to point to the required interface and operation.
Your newly created operation will appear on the canvas on top of the
transition that it is associated with.
Note: There are some rare instances
in the runtime environment when an operation can exist and not be associated
with a transition. If this operation is triggered during execution, then one
of two things can occur. If a fault is defined on the operation, it is returned;
otherwise, the state machine does nothing, and sits in the current state and
waits for a valid operation.