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chaPter 10 • object-oriented systems analysis and design Using Uml 273

Boundary
or Entity Control
interface class class
class

:View :View :Calculate
Student Student :Student :Section :Course Grade
User Interface Point
Interface Controller Average

Student

provide
userLogon logon( ) getStudent( )
display student- return student- return
WebPage WebPage studentData

click send
nextButton studentNumber( ) getSection( )
calculateGPA( )
return
sectionGrade
getCourse( )
getCredits( )

return credits
return courseData

display return
courseWebPage courseWebPage return GPA

Figure 10.15
A sequence diagram for using two web pages: one for student information and one for course information.

The :Course class returns the credits, which enables the :Calculate Grade Point Average class
to determine the GPA and return it to the :View Student Interface Controller.
The :View Student Interface Controller would repeat sending messages to the :Section
class until all sections for the student have been included. At this time, the :View Student
Interface Controller would send the courseWebPage to the :View Student User Interface
class, which would display the information in the browser.
Using the user interface, control, and entity classes also allows the analyst to explore and
play with the design. The design mentioned previously would display all the student personal
information on one page and the course information on a second page. The analyst may modify
the design so that the student personal information and the course information appear on one web
page. These two possible scenarios would be reviewed with users to determine the best option.