I am creating the Sequence diagram that represents sending friendship requests from User 1 to user 2. The requests are stored in Firebase Realtime Database. User 2 is notified by Firebase Cloud Messaging that subscribes to topic which is user id. User 2 can deny or accept the request. This scenario I would like to model by sequence diagram. I have created this diagram so far. I am not sure how to capture action 1.1. After logging FCM is subscribed to user id. How would you model accept or deny of the request?
The following is a way to model it:
User 2reacts on the notification with either acceptance or rejection. You can model both in one diagram with a fragment. Or you create two diagrams for either case.N.B. The sequence numbers at the messages are superfluous in SDs and only meaningful in ADs. You can turn them off in VP somewhere in the context menu of the diagram (IIRC).