UML series: (3) Sequence Diagram

1. The function of time sequence diagram

A timing diagram Sequence Diagram is an interaction diagram that emphasizes the chronological order of messages.

Timing diagrams describe the interaction between objects and objects in a class system.

A timing diagram is a model that describes how groups of objects interact with each other over time.

2. The elements of the sequence diagram

Role (Actor)

Object (Object)

Lifeline (Lifeline)

Message (Message)

Self-associated message (Self-Message)

3. User login sequence diagram

Summary of time sequence diagram

(1) the timing diagram only describes the ideal workflow, so it does not involve "branch flow, NULL pointer exception judgment" and so on.

(2) the sequence diagram tool does not have "roles". You can create roles in the use case diagram, and then drag the roles in the project into the sequence diagram.