cosc 3351 software design an introduction to uml (ii)gabriel/courses/cosc3351_s08/sd_06_uml2.pdf ·...

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Edgar Gabriel

COSC 3351

Software Design

An Introduction to UML (II)

This lecture contains material from:

http://dn.codegear.com/article/31863

Edgar Gabriel

Spring 2008

COSC 3351 – Software Design

Edgar Gabriel

Packages

• Classes can be grouped into packages

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Edgar Gabriel

Sequence diagrams (I)

• A sequence diagram is an interaction diagram that

details how operations are carried out -- what messages

are sent and when.

• Sequence diagrams are organized according to time.

The time progresses as you go down the page.

• The objects involved in the operation are listed from

left to right according to when they take part in the

message sequence.


Edgar Gabriel

Sequence diagrams (II)

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Edgar Gabriel

Example: course enrollment system

• Problem description:

– Users must be able to view a menu of available courses

and select a course

– Once selected, a pop-up allows to enter: name, phone,

fax and e-mail address

– User can select payment option: check, purchase order,

credit card

– Once all information is provided, user has to click on

submit button -> another screen pops up summarizing all

information and instructs user to print, sign and fax the

copy

– E-mail is sent automatically to an Enrollment Clerk (EC)

about the user and the subscription


Edgar Gabriel

Example: course enrollment system (II)

– System knows maximum number of students for each

class and marks classes as ‘sold out’ if limit is reached

– EC can e-mail all students enrolled in a course by bringing

up a special form -> select course, type message

– EC can bring up a form that shows status of all students

for all courses that have already been taught.

• Status will indicate whether student was attending

and whether student has payed

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Edgar Gabriel

Identifying Actors

• Enroller: This actor enrolls a student in a course

• Enrollment Clerk: This actor receives e-mail

notification of each enrollment. It also sends e-mail

notices to students and receives reports about

enrollments and payments

• Student: This actor receives e-mail notification of

enrollment and e-mail notifications from the

Enrollment Clerk. The student attends the courses it is

enrolled in.


Edgar Gabriel

Use case 1

• Use case 1: View Menu of

choices

– Enroller requests list of

courses

– System displays list of

courses

– Included are name, place,

time and cost of the course

– List will also show number

of students allowed and

currently enrolled

View Menu

of choices

Enroller

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Edgar Gabriel

Use case 2• Use case 2: Enroll in a course

– Enroller views menu of courses

(Use case 1)

– Enroller selects course

– System prompts for name,

phone, fax, email, address and

preferred payment

• Extension point: fill out

payment method

– Other use cases will be

extending this use case

– Used whenever there are many

alternatives within a part

View Menu

of choices

Enroller

Enroll in a course

Extension points:fill out payment

method

Student

<<include>>

Enrollment Clerk


Edgar Gabriel

Use case 2 & 3

• Use case 2.1: pay by purchase order

• Use case 2.2: pay by check

• Use case 2.3: pay by card

• Use case 3: email messages to

students

Enroll in

course

Pay by PO Pay by check Pay by card

<<extend>>

Email msgs.

to studentsEnrollment Clerk

Student

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Edgar Gabriel

Use case 4

• Use case 4: set attendance

– Select a class and a student

that is enrolled in that class

– System presents student and

shows whether the student

attended the class and

payment has been received

Enrollment Clerk

Set

attendance


Edgar Gabriel

Use case 5

• Get student status:

– EC selects student

– Extension point: select student of

interest

• Use case 5.1: select students in a course

– List all courses, EC selects a course

– System shows all students in the

course

• Use case 5.2 select unpaid students

– EC indicates that the system should

select all unpaid students

Get student status

Extension points:Select students of

interest

Select students

in course

Select unpaid

students

<<extend>>

Enrollment Clerk

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Edgar Gabriel

System Boundary Diagram

View Menu

of choices

Enroll in

course

Email msgs.

to students

Set

attendance

Get student status

Enrollment Clerk

Student

Enroller

<<include>>


Edgar Gabriel

Domain model

• Set of diagrams that help to define the terms that

appear in the use cases (descriptive tool)

• Show key objects within the problem and their

relationships

• The domain model is not necessarily the model of the

software to be built!

• We will depict domain models using the <<type>>

stereotype in the class diagrams

– UML allows to substitute different icons for different

stereotypes (e.g. you could represent a domain model as

a cloud to clearly distinguish them from classes)

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Edgar Gabriel

Domain Model (I)

• 1. Abstraction: The course catalog

– List of courses that are offered

– Problem with this abstraction: the same model could be

offered multiple times at different locations

• Need to separate the course from the schedule (date,

location, instructor)

<<type>>

Course Catalog

Add Course()

Remove Course()

<<type>>

Course

Fee: Currency

Enrollment limit: integer

Current enrollment: integer

0..n


Edgar Gabriel

Domain Model (II)<<type>>

Course Catalog

Add Course()

Remove Course()

<<type>>

Course

Fee: Currency

Enrollment limit: integer

0..n

<<type>>

Session

Session date

Current enrollment

instructor

Add Student()

Remove Student()

<<type>>

Session Schedule

Add Session()

Remove Session()

0..n

<<type>>

Student

Paid: bool

Attended: bool

enrolled in

0..n

schedules

offers

teaches

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Edgar Gabriel

What we’ve learned from the domain

model• Use cases employ the wrong language!

– Course catalog and courses have to be replaced in the use

cases by session schedules and session

– Some use cases have been left out

• Need to maintain Course Catalog and Session Schedule

• Courses and Sessions need to be added and removed

from Course Catalogs/Session Schedules

• Creating the Domain Model helps us understand the

problem


Edgar Gabriel

Deciding the Architecture/Software

Platform• Choices

– A Web-based CGI application

– A database application

– Visual XYZ

– Write everything from scratch in C

• -> we choose CGI for this case

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Edgar Gabriel

Web architecture

• Need to decide on the number of web-pages, what CGI

scripts shall be invoked etc…

<<cgi>>

Session Menu

Generator

<<html>>

Session Menudepends


Edgar Gabriel

Web Architecture (II)

<<html>>

Session Menu

<<cgi>>

Session Generator

<<cgi>>

Enrollment Form Generator

<<html>>

Enrollment Form

<<cgi>>

Enroll

<<html>>

Enrollment

Error

<<html>>

Enrollment

Confirmation

<<html>>

Banner

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Edgar Gabriel

Database Interface Layer

• Each CGI program must have access to the data

representing students, classes, schedules etc.

– We call it the training database

• To keep the access independent of a particular data

base, we introduce a Database Interface Layer (DIL)

Training

Application

Training

DIL Training

Databasedepends depends


Edgar Gabriel

Database Interface

• Classes within the training application need to access

the database

• This will be accomplished through a set of interfaces

inside the Training Application

• Interfaces are implemented by classes in the DIL

package

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Edgar Gabriel

<<type>>

Session Schedule

<<interface>>

Session Schedule

+GetSessionIterator():iterator<Session>

DIL:: Session Schedule DIL:: Session DIL:: Course

<<interface>>

Session

+GetCourse():Course

+GetDate(): Date

+GetLocation(): string

+GetTime(): Time

<<interface>>

Course

+GetCourseName():string

+GetCost():float

<<type>>

Session

<<type>>

Course

imports

realizes


Edgar Gabriel

Session Menu Generator

• Corresponds to the 1st use case

• Goal: Build an HTML representation of a session

schedule

– Merge an HTML template with the actual data from a

session schedule

– Program will use the SessionSchedule interface to access

Session and Course instances in the database, in order to

get names, times, locations and fees.

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Edgar Gabriel

: Session Menu

Generator

: HTML Template

: Session Schedule

: iterator<session>

: Session : Coursecreate

GetSessionIterator

GetNext

GetCourse

GetTime, GetLocation

GetCourseName, GetCost

SessionIterator

Session

Course

Time, Location

Name, Cost

For each session in iterator<session>

Insert (“Schedule”,

lineItem

generate

destroydestroy

cosc 3351 software design an introduction to uml (ii)gabriel/courses/cosc3351_s08/sd_06_uml2.pdf ·...

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