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This article mainly introduces the example analysis of the unified modeling language UML, which has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, let the editor take you to understand it.

First, the origin of the standard modeling language UML

Progress has been made in the field of software engineering from 1995 to 1997, and its achievements exceed the total achievements in the field of software engineering in the past 15 years. One of the most important and epoch-making achievements is the emergence of the Unified Modeling language (UML:Unified Modeling Language).

In the world, at least in the past 10 years, UML will be the dominant standard modeling language in the field of object-oriented technology. It is absolutely necessary to adopt UML as the unified modeling language in China: first of all, dozens of object-oriented modeling languages in the past are independent of each other, and UML can eliminate some potential unnecessary differences and avoid confusion among users. Secondly, through unified semantic and symbolic representation, we can stabilize China's object-oriented technology market and make the project rooted in a mature standard modeling language, which can greatly broaden the scope of application of the software system developed and developed. and greatly improve its flexibility.

Unified Modeling language (UML) in UML introduction is a language used to describe, construct, visualize and document software-intensive systems.

First of all, and most importantly, the unified modeling language combines the concepts of Booch, OMT and OOSE methods. It is a simple, consistent and general modeling language that can be widely used by users of these and other methods.

Secondly, the unified modeling language expands the scope of application of existing methods. In particular, it is worth mentioning that the developers of UML regard the modeling of parallel and distributed systems as the design goal of UML, that is, UML has the ability to deal with such problems.

Third, the unified modeling language is a standard modeling language, not a standard development process. Although the application of UML must be based on the development process of the system, according to our experience, different organizations and different application areas need different development processes. For example, developing intricate software is a very interesting task, but developing such software is very different from building a strict real-time avionics system, which is a matter of life and death. Therefore, we first focus on designing general metamodels (unifying the semantics of different methods), and the second is to establish a general representation (to provide a visual representation of these semantics). While UML developers will continue to advocate a software development process that has been repeatedly improved and added from use-case-driven to architecture-centric, it is not necessary to design a standard development process.

UML is a well-defined, easy to express, powerful and universally applicable modeling language. It integrates new ideas, new methods and new technologies in the field of software engineering. Its scope is not limited to supporting object-oriented analysis and design, but also supports the whole process of software development starting from requirements analysis.

The development of object-oriented technology and UML can be represented by the figure above, and the emergence of standard modeling language is an important achievement. In the United States, as of October 1996, UML has been widely supported by industry, science and technology and application circles. More than 700 companies have expressed support for using UML as a modeling language. By the end of 1996, UML has firmly accounted for 85% of the object-oriented technology market and has become the de facto industry standard for visual modeling languages. On November 17,1997, OMG adopted UML 1.1 as a standard modeling language based on object-oriented technology. UML represents the development direction of object-oriented software development technology, and has a huge market prospect, but also has great economic value and national defense value.

Second, the content of the standard modeling language UML

First of all, UML integrates the basic concepts of Booch, OMT and OOSE methods, and most of these basic concepts are the same as those in other object-oriented technologies. Therefore, UML is bound to become a simple and consistent modeling language that users of these and other methods are happy to adopt. Secondly, UML is not only a simple confluence of the above methods, but also widely solicited opinions on the basis of these methods. UML expands the application scope of existing methods. Third, UML is a standard modeling language, not a standard development process. Although the application of UML must be based on the development process of the system, different development processes need to be adopted because of different organizations and different application fields.

As a modeling language, UML introduces that the definition of UML includes two parts: UML semantics and UML representation.

(1) the semantic description of UML is based on the precise metamodel definition of UML. The metamodel provides a simple, consistent and universal definition for all elements of UML in syntax and semantics, enabling developers to be consistent in semantics and eliminating the impact of person-to-person expressions. In addition, UML supports extended definitions of metamodels.

(2) UML notation defines the representation of UML symbols, which provides a standard for developers or development tools to use these graphical symbols and text syntax for system modeling. These graphic symbols and words express the application-level model, and semantically it is an example of the UML metamodel.

Let's take a look at the important content of UML in the introduction to UML, which can be defined by the following five types of diagrams (a total of 9 graphics):

The ◆ * * class is a use case diagram that describes the function of the system from the user's point of view and indicates the operator of each function.

The second type of ◆ is static diagrams (Static diagram), including class diagrams, object diagrams, and package diagrams. The class diagram describes the static structure of the class in the system. Not only define the classes in the system, represent the relationships between classes, such as association, dependency, aggregation, etc., but also include the internal structure of the class (class properties and operations). The class diagram describes a static relationship that is valid throughout the life cycle of the system. An object diagram is an instance of a class diagram, using almost the same identity as the class diagram. The difference between them is 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. Because the object has a life cycle, the object graph can only exist for a certain period of time in the system. A package consists of packages or classes that represent the relationship between packages. The package diagram is used to describe the hierarchical structure of the system.

The third type of ◆ is behavior Graph (Behavior diagram), which describes the dynamic model of the system and the interaction between the constituent objects. The state diagram describes all the possible states of the object of the class and the transition conditions of the state when the event occurs. In general, a state diagram is a supplement to a class diagram. In practice, it is not necessary to draw state diagrams for all classes, 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 to identify parallel activities. This is the end of the UML behavior diagram. Let's take a look at the interaction diagram.

The fourth type of ◆ is the interaction diagram (Interactive diagram), which describes the interaction between objects. The sequence diagram shows the dynamic cooperative relationship between objects, which emphasizes the order of messages sent between objects and shows the interaction between objects at the same time; the cooperation diagram describes the cooperative relationship between objects, and the cooperation diagram is similar to the sequence diagram to show the dynamic cooperative relationship between objects. In addition to displaying the exchange of information, the collaboration graph also shows objects and their relationships. If you emphasize time and sequence, use the sequence diagram; if you emphasize the relationship between superiors and subordinates, select the cooperation diagram. These two kinds of graphs are called interactive graphs.

The fifth category of ◆ is the implementation diagram (Implementation diagram). The component diagram describes the physical structure of the code components and the dependencies between the components. A part may be a resource code part, a binary part, or an executable part. It contains information about logical classes or implementation classes. Component diagrams help to analyze and understand the degree of interaction between components.

The configuration diagram defines the physical architecture of software and hardware in the system. It can display the actual computers and devices (represented by nodes) and the connections between them, as well as the types of connections and dependencies between components. Within the node, executable components and objects are placed to display the correspondence between the node and the executable software unit.

From the perspective of application, when using object-oriented technology to design the system, the first step is to describe the requirements; secondly, to establish the static model of the system according to the requirements to construct the structure of the system; the third step is to describe the behavior of the system. The models established in the * * step and the second step are static, including use case diagram, class diagram (including package), object diagram, component diagram and configuration diagram, which are the static modeling mechanism of the standard modeling language UML. The model established in the third step can either be executed or represent the timing state or interaction at the time of execution. It includes four graphs: state diagram, activity diagram, sequence diagram and cooperation diagram. It is the dynamic modeling mechanism of the standard modeling language UML. Therefore, the main contents of the standard modeling language UML can also be classified into two categories: static modeling mechanism and dynamic modeling mechanism.

Thank you for reading this article carefully. I hope the article "sample Analysis of Unified Modeling language UML" shared by the editor will be helpful to you. At the same time, I also hope that you will support and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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