This section introduces the UML modeling language, mainly including the concepts of modeling language and the five types of UML diagrams. I hope that you will have a new understanding of the UML modeling language through the study of this section. Let's learn the UML modeling language together.
UML Modeling Language
Unified Modeling Language (UML is short for Unified Modeling Language) is a language for visual modeling of software-intensive systems. UML is a standard language for specifying, visualizing, and documenting products of object-oriented development systems.
The important content of the standard modeling language UML can be defined by the following five types of diagrams (9 types of diagrams in total):
The first category is use case diagrams, which describe system functions from the user's perspective and indicate the operators of each function.
The second category is static diagram (Staticdiagram), including class diagram, object diagram and package diagram. The class diagram describes the static structure of the classes in the system. It not only defines the classes in the system, but also represents the relationship between classes such as association, dependency, aggregation, etc., but also includes the internal structure of the class (class attributes and operations). The class diagram in the UML modeling language describes a static relationship that is valid throughout the life cycle of the system.
Object diagrams are instances of class diagrams and use almost the exact same identification as class diagrams. They differ in that the object graph shows multiple object instances of the class, not the actual class. An object diagram is an instance of a class diagram. Since objects have a life cycle, the object graph can only exist for a certain period of time in the system.
Packages in the UML modeling language are composed of packages or classes, which represent the relationship between packages. A package diagram is used to describe the hierarchical structure of a system.
The third category is Behaviordiagram, which describes the dynamic model of the system and the interaction between the constituent objects. The state diagram describes all possible states of the object of the class and the transition conditions of the state when the event occurs. Often, state diagrams are complementary to class diagrams. In practice, it is not necessary to draw state diagrams for all classes, but only for those classes that have multiple states whose behavior is affected by the external environment and changes.
The activity diagram describes the activities to be carried out to meet the requirements of the use case and the constraint relationship between the activities, which is helpful for identifying parallel activities.
The fourth category is the interactive diagram (Interactivediagram), which describes the interaction between objects. The sequence diagram in the UML modeling language shows the dynamic cooperation relationship between objects. It emphasizes the order in which messages are sent between objects and shows the interaction between objects. The cooperation diagram describes the cooperation relationship between objects. The cooperation diagram is similar to the sequence diagram. Displays dynamic partnerships between objects. In addition to showing the exchange of information, cooperation diagrams also show objects and the relationships between them. If time and order are emphasized, use sequence diagrams; if superior and subordinate relationships are emphasized, choose cooperation diagrams. These two types of graphs are collectively called interaction graphs.
The fifth category is the implementation diagram (Implementationdiagram). The component diagram describes the physical structure of the code components and the dependencies between the components. A component may be a resource code component, a binary component, or an executable component. It contains information about the logical class or the implementation class. Component diagrams help to analyze and understand the degree of interaction between components.
refer to:
UML overall cognition https://blog.csdn.net/sky15732625340/article/details/49840987
[Full-process modeling] The development relationship between class diagrams and sequence diagrams, and the whole-process modeling from use cases https://blog.csdn.net/qingrun/article/details/6070994
UML (eight) sequence diagram https://blog.csdn.net/u010191034/article/details/17651483