1. describes the interaction between objects.
2. Emphasize the chronological order
Developers usually use it to simulate object interaction in a scene. It explains how different components in the system interact with each other to achieve a specific function, and the order in which the interaction occurs in a specific scenario.
Timing diagram is to mark the time sequence of interaction with a time line from the top step by step. Each object corresponds to a column, and the messages passed between them are represented by arrows.
This paper describes how people want to use a system to show more clearly the relevant users, the services that users need from the system and the services that the system needs from users, so that system users can understand the purpose of these elements more easily and developers can finally realize these elements.
Use case diagram is a view that describes the external characteristics of software products, describes requirements from the perspective of users, and analyzes the functions and dynamic behaviors of products.
Use case diagram includes three aspects: use case, participants and the relationship between participants and use cases.
Class diagram is a static diagram that describes the system according to the classes in the system and their relationships. It consists of multiple classes and relationships between classes.
(1) shows the structure of information in the system;
(2) Describe the behavior of the information in the system;
(3) Define a basis for other diagrams (such as sequence diagrams and interaction diagrams);
An object graph contains objects and links. An object is a concrete instance of a class, and a chain is an instance of the relationship between classes, representing the concrete relationship between objects.
As a snapshot of the system at a certain moment, the object graph is a static portrayal of each class in the class graph at a certain point in time and its relationship.
(1) explains the complex data structure, which is helpful for abstraction.
(2) Representing behavior in snapshots. Through a series of snapshots, the behavior of things can be effectively expressed.
Activity diagram models the dynamic behavior of the system and describes the sequence of activities, which is essentially a flow chart showing the control flow from one activity to another.
Activity diagram element
Also known as structure diagram, it describes the physical aspects of the system. It can describe the components of the system, the interfaces provided by the components, the demand interfaces, the ports and their relationships.
This is very important in the system model based on component development.
This paper describes the hardware nodes when the system is running, the physical location of the software components running on these nodes and the static view of how they communicate with each other.
Describes the dynamic behavior of an object during its existence, which is represented by the state sequence experienced by the object, the events leading to the state transition and the actions accompanying the state transition.
A digital time axis is used to accurately describe the sequence of messages and intuitively represent the state change of each lifeline.
Usually used to simulate real-time events.