Indicate a message between objects in a sequence diagram

In a sequence diagram, drag a Message shape onto the drawing page.

The message shape you choose depends upon the kind of message you want to send (regular, asynchronous, procedure call, or return).

Glue the message endpoint without the arrowhead to a connection point on the lifeline of the object sending the message.

Glue the message endpoint with the arrowhead to a connection point on the lifeline of the object receiving the message.

Double-click the message, and then type or choose the message name, stereotype, sequence expression, and flow kind.

For a flat message or procedure call, choose the operation you want the message to generate. If the operation doesn't exist, click New to create it.

For an asynchronous message, choose the signal you want the message to generate. If no reception for the signal exists on the classifier that the object lifeline receiving the message is based on, click New to create the reception.