UML modeling-use case diagram

Three elements of use case diagram design

1. Participants

2. Use Cases

3. Relationship

 

1. The relationship between participants is generalized (inherited.

 

2 Relationship between participants and Use Cases

 

 

 

A solid arrow indicates the relationship between active and passive. Such as the relationship between participants and use cases. It represents an association between operations.

3 Relationship Between Use Cases

The relationship between use cases mainly uses three types of relationships, namely, inclusion, extension, and generalization.

3.1 include)

Solid arrow plus <include>

 

 

Event streams containing use cases are inserted into the event streams of the basic use cases.

Give an example:

There will be a printed receipt for queries, withdrawals, and transfers in the ATM. We can extract the printed receipt as a use case, and the original query, withdrawal, all three use cases of transfer include this use case. Generally, multiple use cases are commonly used to include one use case.

3.2 extended relationship (extend)

Solid arrow plus <extend>,

The event stream of the extended use case is inserted into the event stream of the basic use case according to the extension point under certain conditions, that is, you can determine whether to insert data to the event stream of the basic case based on certain conditions, and you can use multiple extension points.

For example:

For example, there can be extended functional use cases of "Call wait" and "call transfer" for basic calls. If the recipient's call is busy, call and wait. If the recipient is not convenient to answer the call, call and transfer the call.

3.3 generalized relationship

 

 

 

 

Empty triangle solid arrow

Meaning: represents a special relationship. It means similar to the concept of inheritance in object-oriented programming. Inheritance relationship

For example:

Ticket Booking is a generalized use case. The specific use case can be telephone booking or online booking.

In addition, if you want to add some comments to a use case, it is easier to communicate and understand. We use a comments component diagram to connect to a dotted line. For example

References:

IBM Fu chunyi's "Use Case modeling Guide"

Ice country blog Co., http://www.pycsky.com/use-case/115.