Introduction
Beef Brisket News Release system looks very feel, a line of feeling, after all, this is a system implementation of the tutorial, including a variety of details, although just looked at 10 episodes around, but deeply by the beef brisket Teacher's explanation of ideas brought in, especially some of the previous learning process neglected details, rice teacher said, At present, learning knowledge, follow-up learning will also be encountered. Really, learning is a circle, this feature is specifically used to assess the effectiveness of our previous studies, and give us the opportunity to check the gaps.
BodyBeef Brisket Video Opening the teacher led us to draw the use case diagram of this system, so take this opportunity, I went over the use case diagram of several relationships:
Association (Association)
Includes (include)
Extension (Extend)
Generalization (generalization)
Association Relationship
Describes the relationship between actors and use cases.
Use a one-way arrow to indicate who initiated the use case.
Each use case has a role to start, in addition to the include and extend use cases.
include relationshipRefers to a relationship between two use cases. The behavior of one of the use cases (basic use cases, Base uses case) contains the behavior of another use case, which contains use cases, inclusion uses case.
If more than two use cases have a lot of consistent functionality, you can break this functionality into another use case, and other pull-pulls can establish containment relationships with the use case.
The example above is that the query, withdrawal and transfer Three use cases have a consistent function, so this feature is extracted as a use case. And the three use cases and the extracted use cases are the included relationships.
The included use cases can also be executed when the basic use cases are executed, and the included use cases can be executed separately.
If a use case has too many functions, it can be modeled as two or more small use cases with containment relationships.
Extended Relationships
Also refers to the relationship between two use cases. A use case can be defined as an extension of the increment of the underlying use case, called as an extension relationship. Extended relationships are methods that insert new behavior into existing use cases. The underlying use case does not involve extension cases even if no extension cases are performed, and the extension use case is only executed if a specific condition occurs.
generalization (inheritance) relationshipsA generalization relationship is formed between a use case and the use case of several cases. The parent use case is often represented as an abstract use case.
The local sub-use cases where any parent use case appears can also appear.
practice of real problem
"Typical Problem 1-2-2" (2005 first half questions 2, 3)
In the case modeling process, if several use cases perform the same functional steps, these public steps can be extracted into separate use cases. This use case is called (1); On a UML use case diagram, this relationship between use cases is marked as (2).
(1) A. Extension use case B. Abstract use case C. Public use case D. Participate in use cases
(2) A. Association B. Extends C. Uses D. inheritances
Key points of Analysis:
Use cases describe a sequence of actions that interact with system participants and are executed by the system. The UML specification provides a relationship of 3 dependencies, including (include), extension (extend), and generalization (generalization) between use cases, and the various relationship functions and differences are shown in the following table:
use case diagram various relationship description table
From the above analysis, the abstract use case is a separate use case that extracts public steps from several use cases that perform the same functional steps. It can be seen that abstract use cases represent some form of "reuse", which is a tool for reducing redundancy between use cases. For example, in an order entry subsystem, creating a new order and updating an order requires verifying that the user account is correct. Then, the use case "create New Order", "Update Order" and the use case "Check customer account" is a inclusion (include) relationship.
The Association (association) for option A is a relationship between two or more specific classes that describe the connection of instances of these primitives. The "Inheritance (inheritances)" of option D describes the general relationship between child use cases and parent use cases.
The general idea of answering this kind of question is the 3 relationships of memorizing use cases.
Reference answer: (1) B; (2) C.
End
I believe that everyone in the machine room reconstruction or cooperation, the computer is installed on the EA, I am learning a bit of a dead end, look at some lines with rational rose, some lines with arrows, I feel that each software expression of the same relationship is the same, so with rational rose after drawing , not very accustomed to the EA in those lines (the self-mastery of the weak is also a party to meet), so I carefully revisit the use case diagram related knowledge. Let's take a look at what the use case diagram of the EA draws is:
Beef Brisket Press Release system--use case diagram knowledge, restudying
