Use case diagram of UML

Use case diagram Structure

1
Roles: Personnel roles-people and events;

Roles are not necessarily limited to people. They can also be things or things.

2. Use Case: function description;

Each use case describes a complete system service.

3
System boundaries

4
Relationship: the relationship between executors and use cases.

Generalization

Dependency

Association

Aggregation and combination

Implementation

 

You can read books, roles, system boundaries, use cases, and relationships between roles and use cases. All use cases are within the system boundary, indicating that they belong to a system. The role is placed outside the system boundary. The table name role does not belong to the system, but is responsible for directly driving the execution of associated use cases.

1 Role

It is usually represented by a scarecrow.

The role is assumed by the user. The role exists because the role interacts with the system. Otherwise, the role is unnecessary. A role is a class rather than an object. Therefore, we can introduce inheritance relationships between classes.

Relationship between roles

Because a role is essentially a class, it has the same relationship description as the class, that is, there is a general relationship between the roles, the meaning of the generalized relationship extracts the common behaviors of some roles and expresses them as common behaviors.

2 Use Cases

Use Cases are used to describe the complete functions that a role can feel. In the UML specification text, use cases are defined as "an action sequence executed by the system. And can generate an observed result value to a specific role.

(1) Use Cases are usually driven by a role.

(2) Use Cases Report the execution result value to the role.

(3) Use Cases have functional integrity.

The graphic operator is an elliptical shape.

 

Main attributes of Use Cases

L event stream

L prerequisites

L post Condition

L SPECIAL REQUIREMENTS

L extension point

L Problem Description

An event stream describes the interaction process of a use case between the executor and the system. This process contains multiple branches. Include

Basic stream

Alternate stream

========================================================== ========================================================== ===

Relationship between Use Cases

L inclusion relationship

There is always a function to maintain XX information in the business. If you use this function as a use case, it is too complex to create, edit, and modify the information; if it is divided into new use cases, edit use cases, and delete use cases, the Division is too detailed. The contained relationship can be used to clarify the relationship.

L generalized relationship

Child Cases inherit all structures, behaviors, and relationships of the parent case. A child use case can use a behavior of the parent use case or reload it. The parent case is usually abstract.

Extended relationships

The system allows you to export and print the query results. For queries, whether or not the query can be exported or printed is the same, and export and printing are invisible. Export, print, and query are relatively independent, and new behaviors are added to the query. The basic meaning of an extended link is similar to that of a generalized link. However, in an extended link, there are more rule restrictions on the extended use case. The basic use case must declare the extension point, extended use cases can only add new behaviors and meanings to the extended points. Like the inclusion relationship, the extension relationship is also the dependency type. In the extended relationship, arrows are directed from the extended case to the basic case, which is different from the contained relationship.

Granularity and scope of Use Cases

L overview level

L user Objectives

L sub-functions

The granularity and sub-function abstraction of use cases become reusable relationships.

Link

N Generalization

N dependency

N join

N Implementation

In case analysis, actual analysis may be required, which is inevitable. Here is an example.

Is an example of a Data room Charging System

 

 

For author information, see (Netease blog
Http://hanhan2010.blog.163.com /)