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What is a Domain Model? ● Use cases looked at the system’s environment (actors) and the system’s external behavior. ● Use cases consider the system as a black box and help us understand how the system as a whole interacts with the outside word. ● Now we turn to consider the inside of the system. We do this by building the domain model, which shows what the black box (the system) encloses. ● uses cases elaborate the system’s behavioral characteristics (sequence of stimulus-response steps), ● domain model gives details of the systems structural characteristics (system parts and their arrangement) S.H 2009 Software EngineeringOO Domain Modeling
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OO DomainModeling With UML Class Diagrams and
CRC CardsChapter 6
Princess Nourah bint Abdulrahman UniversityCollege of Computer and Information Sciences
Department of Computer Science
Dr. Doaa Sami Khafaga
Objectives
The main objective of this chapter is to know: how to properly use the most essential features of UML class diagrams, and the typical problems you will encounter when modeling with class diagrams.
In this chapter we:
● Introduce the evolutionary approach for building classes
● Explain how to identify objects and attributes of classes
● Describe the technique of CRC ‘Class Responsibility and Collaborator’
● Explain how classes are related in a class diagram
● Explain generalization, association, aggregation and composition
● Introduce object diagramsS.H2009
Software Engineering OO Domain Modeling
What is a Domain Model?● Use cases looked at the system’s
environment (actors) and the system’s external behavior.
● Use cases consider the system as a black box and help us understand how the system as a whole interacts with the outside word.
● Now we turn to consider the inside of the system. We do this by building the domain model, which shows what the black box (the system) encloses.
● uses cases elaborate the system’s behavioral characteristics (sequence of stimulus-response steps),
● domain model gives details of the systems structural characteristics (system parts and their arrangement)
S.H2009
Software Engineering OO Domain Modeling
What is a Domain Model?
● uses cases elaborate the system’s behavioral characteristics (sequence of stimulus-response steps),
● domain model gives details of the systems structural characteristics (system parts and their arrangement)
● The next step is to model the inside of the system. We do this by building the domain model, which shows what the black box (the system) encloses.S.H
2009
Software Engineering OO Domain Modeling
What is a Domain Model?
● Illustrates meaningful concepts in the problem domain.
● Usually expressed in the form of static diagrams (in Rational this implies a high-level class diagram).
● Is a representation of real-world things; not software components (of the system under development).
● No operations are defined or specified in the conceptual model.
● Should show concepts, associations between concepts, and attributes of concepts.
● Serves as a source of software objects.
S.H2009
Software Engineering OO Domain Modeling
What is a Domain Model?
Objectives
● identify concepts related to current development cycle requirements
● create initial conceptual model
● Identify attributed
● add specification concepts
S.H2009
Software Engineering OO Domain Modeling
What is a Domain Model?
S.H2009
Software Engineering OO Domain Modeling
What constitutes a good model?
A model should● use a standard notation● be understandable by clients and users● lead software engineers to have insights
about the system● provide abstraction.
Models are used:● to help create designs● to permit analysis and review of those
designs● as the core documentation describing
the system.S.H2009
Software Engineering OO Domain Modeling
From Use Cases to: Objects, Attributes, Operations (methods) -“evolutionary ”
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Software Engineering OO Domain Modeling
Building the Domain Model
A useful strategy for building a domain model is to start with:
● the “boundary” concepts that interact directly with the actors
● and then identify the internal concepts
S.H2009
Software Engineering OO Domain Modeling
Domain Model Relationships
Domain Model
Interaction Diagrams
Dynamic Behavior
Conceptual Class DiagramClasses, attributes, associations
Domain objects
Use Case Model
Functional Requirements
Define terms
Glossary
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Software Engineering OO Domain Modeling
Steps to create a Domain Model
Steps
● 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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Software Engineering OO Domain Modeling
Find conceptual classes
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Software Engineering OO Domain Modeling
Use a category list
● Finding concepts using the concept category list :
● Physical objects: register, airplane, blood pressure monitor
● Places: airport, hospital
● Catalogs: Product Catalog
● Transactions: Sale, Payment, reservation
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Software Engineering OO Domain Modeling
Identify conceptual classes from noun phrases
● Finding concepts using Noun Phrase identification in the textual description of the domain .
● Noun phrases may also be attributes or parameters rather than classes:● If it stores state information or it has multiple
behaviors, then it’s a class● If it’s just a number or a string, then it’s
probably an attributeS.H2009
Software Engineering OO Domain Modeling
Identifying objects
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Software Engineering OO Domain Modeling
Identifying Operations ‘methods’
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Software Engineering OO Domain Modeling
Objects
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Software Engineering OO Domain Modeling
Example: Identify conceptual classes from noun phrasesConsider the following problem description, analyzed for Subjects, Verbs, Objects:
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Software Engineering OO Domain Modeling
The ATM verifies whether the customer's card number and PIN are correct.
SC V R O O A O AIf it is, then the customer can check the account balance, deposit cash, and withdraw cash.
S R V O A V O AV O A
Checking the balance simply displays the account balance.S M O A V O A
Depositing asks the customer to enter the amount, then updates the account balance.
M S V O R V OA V OAWithdraw cash asks the customer for the amount to withdraw; if the account has enough cash,
S M A O V O R OA V S C V O A
the account balance is updated. The ATM prints the customer’s account balance on a receipt.
O A V C S V O A
O
Analyze each subject and object as follows:● Does it represent a person performing an action? Then it’s an actor, ‘R’.● Is it also a verb (such as ‘deposit’)? Then it may be a method, ‘M’.● Is it a simple value, such as ‘color’ (string) or
‘money’ (number)? Then it is probably an attribute, ‘A’.
●Which NPs are unmarked? Make it ‘C’ for class. Verbs can also be classes, for example:● Deposit is a class if it retains state
information
Mapping parts of speech to object model components [Abbott, 1983]
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Software Engineering OO Domain Modeling
Part of Speech
Model Component
Examples
Proper noun Instance AliCommon noun Class Student,
Customer,..Doing verb Operation Buy, check,..Being verb Inheritance Is a kind of, is
one of eitherHaving verb Aggregati
on (Composition)
Has, consists of, includes
Modal verb Constraints Must beAdjective attributes
Attributes 3 years old
Example: a typical description
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Software Engineering OO Domain Modeling
Mapping parts of speech to object model components
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Software Engineering OO Domain Modeling
Identify conceptual classes from noun phrases: POS
● Examine use case descriptions.● Example: Process Sale use case:
● Main success scenario:● Customer arrives at a POS checkout counter.● Cashier starts a new sale.● Cashier enters an item ID.● System records sale line item. It then presents a
description of the item, its price, and a running total.
● ….● ….
● Possible source of confusion: Is it an attribute or a concept?
● If X is not a number or a text then it probably is a conceptual class.S.H
2009
Software Engineering OO Domain Modeling
Example: Initial POS domain model
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Software Engineering OO Domain Modeling
SalesLineItem Item
Sale
Register
StorePayment
Class and Class diagram
• Class naming: Use singular namesbecause each class represents a generalized version of asingular object.
• Class diagrams are at the core of OO Engineering.
• Things naturally fall into categories (computers, automobiles, trees...).
• We refer to these categories as classes.
• An object class is an abstraction over a set of objects with common:
•attributes (states)•and the services (operations)
(methods) provided by each object
• Class diagrams provide the representations used by the developers.
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Software Engineering OO Domain Modeling
Example: Initial POS domain model
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Software Engineering OO Domain Modeling
Example: Initial Domain model of the Monopoly Game
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Software Engineering OO Domain Modeling
Example: Domain model of the Monopoly Game
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Software Engineering OO Domain Modeling
Agile modeling style
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Software Engineering OO Domain Modeling
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Software Engineering OO Domain Modeling
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Software Engineering OO Domain Modeling
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Software Engineering OO Domain Modeling
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Software Engineering OO Domain Modeling
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Software Engineering OO Domain Modeling
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Software Engineering OO Domain Modeling
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Software Engineering OO Domain Modeling
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Software Engineering OO Domain Modeling
Class or Attributes
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Software Engineering OO Domain Modeling
Class or Attributes
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Software Engineering OO Domain Modeling
Description Class
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Software Engineering OO Domain Modeling
Associations
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Software Engineering OO Domain Modeling
Associations
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Software Engineering OO Domain Modeling
Association, aggregation and composition
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Software Engineering OO Domain Modeling
Association between classes Who does What
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Software Engineering OO Domain Modeling
When to show association
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Software Engineering OO Domain Modeling
Associations and implementation
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Software Engineering OO Domain Modeling
Association Notation
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Software Engineering OO Domain Modeling
Association Notation
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Software Engineering OO Domain Modeling
Naming association
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Software Engineering OO Domain Modeling
Applying UML: multiplicity
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Software Engineering OO Domain Modeling
Multiplicity values
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Software Engineering OO Domain Modeling
Applying UML: multiplicity
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Software Engineering OO Domain Modeling
Applying UML: multiplicity
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Software Engineering OO Domain Modeling
Multiple association between two classes
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Software Engineering OO Domain Modeling
Find association
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Software Engineering OO Domain Modeling
Find association
● High priority associations● A is a physical or logical part of B● A is physically or logically contained in/on B● A is recorded in B
● Other associations● A uses or manages or controls B (Pilot -airplane)● A owns B (Airline -airplane)
● Each of the two ends of an association is called a role. Roles have● name● multiplicity expression● navigabilityS.H
2009
Software Engineering OO Domain Modeling
Example: POS Domain Model
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Software Engineering OO Domain Modeling
Example: Monopoly Game Partial Domain Model
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Software Engineering OO Domain Modeling
Attributes
● Attribute - is a logical data value of an object
● Include the following attributes in a conceptual model● those for which the requirements suggest
or imply a need to remember information
● For example:● Sale needs a dateTime attribute● Store needs a name and address.
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Software Engineering OO Domain Modeling
Attributes: UML Notation
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Software Engineering OO Domain Modeling
Suitable attribute types
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Software Engineering OO Domain Modeling
Data types as attributes
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Software Engineering OO Domain Modeling
Attributes are NOT foreign keys
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Software Engineering OO Domain Modeling
Generalization
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Software Engineering OO Domain Modeling