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UML (Unified Modeling Language): A visual modeling language, not a programming language, that supports the entire software development process from requirements analysis.

structure

Generally speaking, the structure of UML includes three parts: building blocks, rules and common mechanisms.

  • Building blocks. UML has three basic building blocks: things, Relationships, and diagrams. Things are an important part of UML. Relationships tie things tightly together. Diagrams are collections of things that are related to each other.

  • Common mechanism. A common mechanism is a common UML method to achieve a specific goal.

  • The rules. A rule is a specification of how the building blocks are put together.

things

  • Structural things: static parts of the model, such as classes, interfaces, use cases, artifacts, and so on;
  • Behavioral objects: dynamic parts of the model, such as interactions, activities, and state machines;
  • Grouping things: An organizational part of a model, such as a package;
  • Annotation thing: The explanatory part of a model, a simple symbol attached to an element or set of elements that constrains or explains it.
  • Part of the UML diagram is as follows:

Relationship between

  • Dependence :– The meaning of one thing changes depending on the meaning of another

  • Association: A structural relationship that describes a set of chains, which are connections between objects. It is divided into combination and aggregation, both of which are the relations between parts and the whole, among which the relations between combination things are stronger. An association between two classes is actually an association between the roles played by the two classes, so there can be multiple associations between two classes identified by different roles.

  • Generalization: General/special relationships, relationships between subclasses and superclasses

  • Implementation: One class element specifies a contract that another class element guarantees to execute.

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A use case diagram

Use case diagrams answer two main questions: 1. Who uses the software? 2. Software functions. It describes the functions of the system from the user’s point of view, and points out the executor of each function, emphasizes the user of the user, and what functions the system accomplishes for the executor.

2 class diagram

According to the use case diagram, a class is abstracted into a static structure diagram, which describes the internal structure of a class and the relationship between classes. In UML class diagrams, the following relationships are common: Generalization, Realization, Association, Aggregation, Composition, and Dependency.

The order of strength and weakness of various relationships: Generalization = implementation > Composition > Aggregation > Association > dependency

3 object graph

Describes the state of each object participating in an interaction at a certain point in the interaction. An object diagram can be thought of as an instance of a class diagram at one point in time.

4 a state diagram

Is a state machine composed of states, transitions, events, and activities, used to describe all possible states of objects of a class and state transition conditions when time occurs.

5 activity diagram

Is a special case of state diagrams, most of which are active. Essentially a flow chart that describes the flow of control from activity to activity.

Interaction diagrams emphasize the flow of control from object to object, whereas activity diagrams emphasize the flow of control from activity to activity.

Activity diagrams are a technique for expressing process fundamentals, business processes, and workflows.

It can be used to model business processes, workflows, use-case realizations, and even program realizations.

6 Sequence diagram – Sequence diagram

A type of interaction diagram that describes the order in which messages are sent between objects, with emphasis on time order.

The main purpose of sequence diagrams is to translate the requirements expressed by use cases into a further, more formal level of elaboration. Use cases are often refined into one or more sequence diagrams. At the same time, sequence diagrams more effectively describe how the responsibilities of each class are assigned and why each class has the corresponding responsibilities.

7 Collaboration diagrams

A type of interaction diagram that describes the organizational relationships of objects receiving and receiving messages, emphasizing the cooperative relationships between objects. Sequence diagrams are laid out in chronological order, while writing diagrams are laid out in spatial structure

Figure 8 components

Component diagram is used to represent the relationship between components, classes or interfaces and components in the system. Among them, the relationship between build diagrams is represented as dependency relationship, and the relationship between defined classes or interfaces and classes is represented as dependency relationship or implementation relationship.

9 Deployment diagram

Describes the configuration of nodes that the system processes and the components that move on the nodes. Physical devices and their connections are emphasized.

The purpose of deploying the model:

Describe the main deployment structure of a specific application. Through the display of various hardware, software in the hardware and various connection protocols, you can describe how the system is deployed. Balance the distribution of computing resources during system operation; It can describe the hardware network structure of the organization or embedded system with various hardware and software related system operation models.