Class diagram II Asper School of Business University of Manitoba Systems Analysis & Design Instructor: Bob Travica Updated: October 2014

Class diagram II

Asper School of Business University of Manitoba

Systems Analysis & Design

Instructor: Bob Travica

Updated: October 2014

3510 Systems Analysis & Design * Bob Travica

2 of 9

Outline

More on associations & multiplicity

Association class

Fully developed classes

Completing procedure for creation of class diagrams


3 of 9

Associations

Association types determined by maximum multiplicity (if 2 symbols for multiplicity provided, read that on the right)

One-to-one (1:1) - occasional;

e.g., Customer—CustomerBillingAddress

One-to-many (1:M) - most frequent; for example:

Customer—Order (or Customer--SaleTransaction)

Many-to-many (M:M) - moderately frequent; examples:

Order—Product (or Item), Employee—Project


4 of 9

Multiplicity question:

Each (one) object on the left side of a relationship can be associated with how many objects on the right side?

Then, write the number on right side.

- Rule: Usually, the same movie plays in several theatres.

Each (one) object on the right side can be associated with how many objects on the left side?

Then, right the number on left side. - Rule: Most theaters play several movies in a day.

Movie Theatre*

Movie Theatre*

Multiplicity (more)

(1, assumed)

(1, assumed)


5 of 9

Association class* Two ways to think about it:

1) A class that stores some extra attributes that characterize (belong to) the association between classes.

2) Extra storage for data that do not fit into either of associated classes.

term


6 of 9

RMO CRM system class diagram (simplified)

Customary simplification, showing:- Just maximum multiplicity- Just attributes of Association Classes

Customary simplification, showing:- Just maximum multiplicity- Just attributes of Association Classes

Figure 8-9modified

Catalog

Item

Order

ItemOrder

Customer

CatalogItemproductPrice

InventoryItem

Shipper

*

*

1 has *

1 *

delivered by

*

1

*

*has

places

delivered by

appears on

*

Shipment*

ItemShipment

quantity

quantitydiscount

• Association class contains transaction data.• In reading multiplicity neglect association classes!

CatalogID

ItemID ItemItemNumber ShipmentNum

ShipperID

OrderNumCustomerID

Optional naming of association classes: CatalogDetail, OrderDetail… (Note word “Detail”).

Optional naming of association classes: CatalogDetail, OrderDetail… (Note word “Detail”).


7 of 9

Fully developed classes (design level)

Methods

Attributes

- = private+ = public() = attribute affected by, input data: string, number = data type

Figure 8-7


8 of 9

Sources for class diagramming

Sources: Description (narrative) Use case diagrams & descriptions Analysis of master data and

transactional data


Completing a class diagram Standard procedure:1. List classes2. List attributes3. Draw simplified class rectangles (name and attribute

segments only)4. Insert attributes in class rectangles 5. Determine keys 6. Draw associations and name them7. (New) Draw Association Class for each relationship

that has attribute(s) on its own.

Note: For now it is important to recognize M:M relationship, not entire multiplicity.

Documents

Class diagram II Asper School of Business University of Manitoba Systems Analysis & Design Instructor: Bob Travica Updated: October 2014