Various relationships between UML use cases

UML is a standard tool for software development and system modeling. The unified modeling language is used to visualize, describe, build, and document the software system.

Here we can see some introduction to UML.

Http://baike.baidu.com/view/23396.htm? Fr = ala0_1_1

This section describes the relationships between UML use case diagrams. the use cases mainly have the following three relationships.

Include

The include relation refers to the use case that can simply contain the behaviors of other use cases and take the behavior of the use case contained in it as part of its own behavior. The inclusion relationship indicates that the time stream of the contained use case is inserted into the time stream of the basic use case.

When dealing with include relationships, the specific approach is to separate the public parts of several use cases into a new use case. There are two main scenarios that require the inclusion relationship.

• When multiple use cases use the same behavior, you can separate the common behavior into a single use case, and then let other use cases include this use case.
• When a use case has too many functions and the event flows through a complex process, you can also abstract an event stream into an included use case to simplify the description.

The following example shows that you need to browse user information after adding and modifying users. Modifying users in the future will not affect user addition or user modification.

 

Extension

Under certain conditions, add new behaviors to existing use cases. The new use cases obtained are called extended use cases.

Differences between extended and contained relationships

• In the extended relationship, the basic use case provides one or more insert points, which provide the insert behavior. In the inclusion relationship, there is only one insert point.
• In an extended relationship, the execution of basic use cases does not necessarily involve extended use cases. Extension use cases are executed only when certain conditions are met. In the inclusion relationship, when the basic use case is executed, it must be executed when it is included.
• Even if there are no extension cases, the basic cases in the extension relationship are complete. The inclusion relationship does not exist completely when the basic use case is not included.

Generalization

Generalization of use cases means that a parent case can be specially divided into multiple child cases.