Reference
Requirements definition
Refer to “Chapter 4-1-1 System development process.”
●Use case diagram
A “use case diagram” is a figure that shows the relationship between system users, functions the system provides, and external systems. An easyto-understand diagram that shows what functions the system possesses,
how they respond when operated, and what role they play from a perspective outside the system can provide a general understanding of the overall
system. Use case diagrams are normally used in the requirements definition stage at the beginning of system development.
Use case diagrams express the functions of a system using the following
symbols:
Symbol
Name
Function
Person
Actor
Represents an entity that plays a role in accessing the system.
Ellipse
Use case
Represents a functionality in the system.
Straight line
Relationship
Represents the relationship between the actor
and the use case.
Rectangle
System boundary
Indicates the scope of the system.
Order management system
Register order information
Modify order information
Search order information
Customer
Employee
① Actors
are drawn outside the system boundary.
② Use cases are drawn within the system boundary.
③ Actors and use cases are connected with lines indicating relationships.
Reference
Class
A “class” defines the object template
that contains the data and methods (operating procedures).
●Class diagram
A “class diagram” shows the structure of the system. It consists of three
parts with the class name on top, attributes in the middle, and operations
on the bottom.
Customer
-
Customer number
Customer name
Address
Phone number
+ Register customer
① “One-to-many”
Order
1 0..*
-
Order number
Order date
Customer number
Order total
+ Register order
relationships are expressed as “1-to-*.”
② “More than zero” is expressed as “0..*.”
③ A “+” sign is placed in front of attributes that can be directly accessed
from all classes.
④ A “–” sign is placed in front of attributes that can only be accessed from
certain classes.
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