Subject: Object Oriented Modeling and Design

Difficulty: Medium

Marks: 4 Marks

Synchronous Message: A synchronous message requires a response before the interaction can continue. It's usually drawn using a line with a solid arrowhead pointing from one object to another. If a caller sends a synchronous message, it must wait until the message is done, such as invoking a subroutine.

Synchronous Message

Asynchronous Message: Asynchronous messages don't need a reply for interaction to continue. Like synchronous messages, they are drawn with an arrow connecting two lifelines; however, the arrowhead is usually open and there's no return message depicted. If a caller sends an asynchronous message, it can continue processing and doesn’t have to wait for a response.

Asynchronous Message