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This article mainly introduces the example analysis of classifier layering in UML sequence diagram, which is very detailed and has certain reference value. Friends who are interested must read it!

UML sequence diagrams represent interactions as a two-dimensional diagram. Longitudinally is the timeline, and time extends downward along the vertical line. The horizontal axis represents the meta-roles of individual objects in collaboration. Meta-roles are represented by lifelines. When the object exists, the character is represented by a dotted line, and when the process of the object is active, the lifeline is a double line.

Classifier layering in UML sequence Diagram

Layering is a general approach to object-oriented design. Generally speaking, systems are always organized into userinterface, process/controller, business, persistence, and system layers (Ambler2001). When the system is designed in this way, it usually strengthens the cooperation of the classifiers belonging to the same layer and reduces the coupling degree of the classifiers of different layers. So it makes sense to layer your UML sequence diagrams in a similar way. In the case of this usage scenario, one hierarchical approach is to first indicate the human role, then the controller class that represents the logic of the context, then the userinterface class, then the business class, and then the related technology class, which encapsulates access to databases and system resources. Layering your UML sequence diagrams in this way makes UML sequence diagrams easier to read and easier to find hierarchical logic problems. Figure 1 takes this approach.

Picture ⒈ a student registration.

Name the role with the same name as your use case diagram.

When you are modeling a usage scenario, your UML sequence diagram usually involves one or more roles. For consistency, the names of the roles displayed in the UML sequence diagram should be the same as those on the use case diagram. UML sequence diagram

Name the class with the same name as your class diagram.

The classes in the UML sequence diagram are the same as the classes in the class diagram, so they should have the same name.

The name of a role can be the same as the name of the class.

In figure 1 you can see a role named student and a class named student. This makes sense because the two classifiers represent two different concepts, roles represent students in real life, and classes represent students in the business application you are building.

Contains a logical narrative description.

Figure 1 can be difficult to understand-- especially for people who are not familiar with reading UML sequence diagrams-- because it is very close to the actual source program. It is common to include a description of business logic in your model, especially when the UML sequence diagram describes a usage scenario, as seen on the left side of the diagram ⒉, which increases the understandability of the diagram, and Rosenberg and Scott (1999) point out that this also provides important information for tracking information between use cases and UML sequence diagrams.

Picture ⒉ online order payment.

Place human and organizational roles on the far left of the diagram.

For business applications, in most cases, the main role is a person or an organization. These roles are often the initiator of the situation and the reading focus of the UML sequence diagram, so they should be placed at the "visible beginning" of the model.

Place the role of the reaction system on the far right of the diagram.

The role of the response system is the system you interact with and should be placed on the far right of the diagram. Because in many business applications, these roles are often referred to as "backendentities", that is, systems that your system interacts with through access technologies, such as CAPIs, CORBAIDL, message queues, or webservice. In other words, put the back-end system in the location of the figure.

Place the system role on the far left of the diagram.

The pilot system role is the system that interacts with your system, and should be placed on the far left of the diagram according to the principle of trying to arrange messages and classifier layers from left to right.

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