Supplier objects call the functions that supply the message and client objects receive the message. Object: A rectangle is used for the object (or role).The notation used in UML communication diagrams is the same as is used in UML sequence diagrams, only much simpler: If your team works with UML diagrams in Confluence a lot, you can customize draw.io to show this library by default.

Scroll down to find the UML shape library in the Software section on the left, make sure the check box is selected, then click Apply.In the left panel, click on More Shapes.

Make sure you enable the UML shape library in draw.io when you want to create a UML communication diagram: If you have multiple scenarios in one use case, UML communication diagrams help you clearly identify what messages (data) need to be sent between objects/roles in each specific scenario. They are simpler than sequence diagrams and only show the messages that pass between the objects or roles in a software program, infrastructure, or any kind of process.

Communication diagrams are another way to visualize the information more commonly represented by UML sequence diagrams.

How to draw sequence diagram online