In sequence diagrams, you can set a message signature by assigning
an operation to it. When you create a message, the operation on the target
interaction instance is created automatically and you are prompted to name
the newly created operation.
You must have a sequence diagram open that contains at least two lifelines
with messages. The property of the target lifeline to which you add the operation
must be a class, interface, or data type.
To assign an operation to a message:
- In the navigation view, click and drag a class, interface, or data
type to a lifeline in the interaction frame. The interaction
instance now represents that source element.
- In the navigation view, click and drag an operation to a message
in the interaction frame. The operation must belong to the source element
that is assigned to the target instance.