Lecture9 Domain model visualizing

1. Domain model: visualizing
concepts
Applying UML and Patterns
-Craig Larman
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2. Domain Model Relationships
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Domain Model
Use Case Model
Interaction Diagrams
Glossary
Design
Requirements
Business Model
Classes, attributes, associations
Domain
objects
Elaboration on some terms

3. A Domain Model
 illustrates meaningful conceptual classes in a problem
domain.
 is a representation of real-world concepts, not software
components.
 is NOT a set of diagrams describing software classes, or
software objects and their responsibilities.
 It may show:
 concepts
 associations between concepts
 attributes of concepts
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4. Domain Model: UML Notation
 Illustrated using a set of class diagrams for
which no operations are defined.
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 A Domain Model is a
description of things in the real
world.
 A Domain Model is not a
description of the software
design.
 A concept is an idea,
thing, or object.

5. A Domain Model is not a Software
Artifact
A Conceptual class:
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Sale
Date
Time
Sales Database
Sale
Date
Time
Print()
Software Artifacts:
vs.

6. Identify Conceptual Classes by Noun
Phrase:
Identify Nouns and Noun Phrases in
textual descriptions of the domain.
Fully dressed Use Cases are good for this
type of linguistic analysis.
It’s not strictly a mechanical process:
Words may be ambiguous
Different phrases may represent the same
concepts.
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7. Steps to create a Domain Model
Identify Candidate Conceptual classes
Draw them in a Domain Model
Add associations necessary to record the
relationships that must be retained
Add attributes necessary for information
to be preserved
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8. Apply the Mapmaker Strategy
Use existing names for things, the
vocabulary of the domain
Exclude irrelevant features
Do not add things that are not there
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9. UML: Associations
VideoVideoStore Stocks 
*1
association name multiplicity
-"direction reading arrow"
-it has no meaning except to indicate direction of
reading the association label
-optional

10. UML: Multiplicity
zero or more;
"many"
one or more
one to forty
exactly five
T
T
T
T
*
1..*
1..40
5
T
3, 5, 8 exactly three,
five or eight
Customer
Video
Rents 
*
One instance of a
Customer may be
renting zero or more
Videos.
One instance of a Video
may be being rented by
zero or one Customers.
0..1

11. GUIDELINES: Associations
 Only add associations for noteworthy relationships.
Literally, those for which making a “note” is worthy or
business motivated. Video
...Rents
Influenced-by 
1
1..*
1 Loan Policy
...
Customer
...
Important association.
Need to remember.
Low value association.
Possible, but so what?

12. UML and GUIDELINES: Attributes
 Show only “simple” relatively primitive types
as attributes.
 Connections to other concepts are to be
represented as associations, not attributes.
Payment
date : Date
time : Time
amount : Money
attributes

13. A Common Mistake - Classes as
Attributes
Rule: If we do not think of a thing as a
number or text in the real world, then it is
probably a conceptual class.
If it takes up space, then it is likely a
conceptual class.
Examples:
A Store is not an attribute of a Sale
A Destination is not an attribute of a flight
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14. Specification or Description Conceptual
Classes
A Class that records information about an
item.
Even if all Instances of the item are sold
out, the description remains.
Avoids duplication of recording the
descriptive information with each instance
of the item.
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15. Description of a Service Example
(Flight)
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Airport
Name
vs.
Flight
Date
Time
Number
Flight
Date
Time
Flight Desc
Date
Time
Airport
Name
Flies-to
Described
-by
Describes
-flights-to

16. The NextGen POS (partial) Domain
Model
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17. The NextGen POS (partial) Domain
Model
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18. The NextGen POS (partial) Domain
Model
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