UML diagram introduction

UML The full name of these three letters is Unified Modeling Language, Direct translation is unified modeling language , Simply put, it's a language with a special purpose .

end UML2.0 Altogether 13 Kind of graphics （UML1.5 Defined 9 Kind of ,2.0 Added 4 Kind of ）. Namely ： Use case diagram 、 Class diagram 、 Object graph 、 State diagram 、 Activity diagrams 、 Sequence diagram 、 Collaboration map 、 Component diagram 、 Deployment diagram 9 Kind of , Package diagram 、 Combined structure chart 、 Interaction Overview 3 Kind of .

• Use case diagram ： Describe system functions from the user's point of view .

• Class diagram ： Describe the static structure of classes in the system .

• Object graph ： The state of multiple objects in a system at a given time .

• State diagram ： It describes the state to state control flow , It is often used in dynamic characteristic modeling

• Activity diagrams ： Describes the workflow of business implementation use cases

• Sequence diagram ： Dynamic collaboration between objects , Emphasize the order in which objects send messages , It also shows the interaction between objects

• Collaboration map ： Describe the assistance relationship between objects

• Component diagram ： A special kind UML Figure to describe the static implementation view of the system

• Deployment diagram ： Define the physical architecture of hardware and software in the system

• Package diagram ： A diagram of grouping the model elements that make up the system

• Combined structure chart ： A diagram that represents a class or constructs an internal structure

• Interaction Overview ： The control diagram of multiple activities

Use case diagram

The use case diagram mainly includes the following 6 Elements

- participants （Actor）
- Use cases （Use Case）
- Connections （Association）
- Inclusion relation （Include）
- Extended relationship （Extend）
- Generalization relation （Generalization）

  participants Actor

  The concept of participants

- An external entity
- Participate in the execution of use cases
- Participants are represented by the roles they play when participating in the use case
- Each actor can participate in one or more use cases

  Types of participants

System users

Real people , The user , Is the most commonly used participant , It exists in almost every system , When naming such participants , It should be named according to the role

Connections （Association）

• Represents the relationship between actors and use cases
• Different actors can access the same use case

The difference between these graphs ：

One ： These nine models have their own emphasis ,

1: Use case diagrams focus on describing user requirements ,

2: Class diagram focuses on describing the specific implementation of the system ;

Two ： The aspects described are different ,

1: Class diagrams describe the structure of the system ,

2: Sequence diagrams describe the behavior of the system ;

3、 ... and ： The level of abstraction is also different ,

1： The component diagram describes the module structure of the system , Higher level of abstraction ,

2： Class diagrams are structures that describe specific modules , The level of abstraction is general ,

3： The object diagram describes the specific module implementation , Low level of abstraction .

Structure classification 、 Dynamic behavior and Model Management ：

1： Structure classification includes use case diagrams 、 Class diagram 、 Object graph 、 Component diagram and deployment diagram ,

2： Dynamic behavior includes state diagrams 、 Activity diagrams 、 Sequence diagrams and collaboration diagrams ,

3： Model management includes class diagrams .