#software-design

Which notation best represents asynchronous message triggers without immediate execution occurrence in UML Sequence Diagrams?

In UML Sequence Diagrams, activation bars (execution occurrences) are used to denote the period during which a lifeline is performing an operation. When modeling asynchronous messaging, an open-headed arrow indicates that the sender does not block for a response. A design challenge arises when a message is sent asynchronously to a receiver, but the receiver