Ch4: Software Architecture and Design

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The role of analysis and design

Software construction may be partitioned into the following phases:

Req. analysis: S/w architecture: High-level/early design: Detailed design: Implementation: Testing:

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The Role of Analysis and Design

Analysis: OO Analysis: Design: OO design:

4

Guidelines for designing classes

Specifying “Good” Classes Identifying a good class is hard work A well-defined class is:

5

Guidelines for design of classes (contd..)

Understanding the utility of classes Three categories of software in application:

Domain independent (20%):

Domain-specific (65%):

Application-specific (15%):

Organizations must strive for domain and organization specific reuse.

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Guidelines for designing classes

Containment vs. inheritance Class D “Is-A-Kind-Of” class C:

Class D “Has-A” class C:

Choose

How and when to apply reuse, relationship among classes. Need discussion,communication and cooperation among engineers.

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History of OO design

Booch: The Booch method Object-Oriented Design with Application,”

Benjamin/Cummings, 1991. Rumbaugh: OMT

“Object-Oriented Modeling and Design,” Prentice-Hall, 1991.

Meyer: Client/Server contract approach “Object-Oriented Software Construction,” Prentice-Hall,

1988. Jacobson: Use-cases and software engineering

“Object-Oriented Software Engineering: A Use Case Driven Approach,” Addison-Wesley, 1992.

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History of OO design (contd..)

Coleman: The Fusion method “Object-Oriented Development - The Fusion Method,”

Prentice-Hall, 1994. Lieberherr: Adaptive OO software

“Adaptive OO Software: The Demeter Method with Propagation Patterns,” PWS, 1996.

Gamma: Design Patterns “Design Patterns: Elements of Reusable Object-Oriented

Software,” Addison-Wesley, 1995. Booch and Rumbaugh: UML Predecessor

“Unified Method for Object-Oriented Development,” Rational TR, 1995

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The emergence of UML

The Unified Modeling Language (UML) is the object-oriented analysis and design equivalent of Java

UML is a language for Web address: http://www.rational.com/uml

UML unifies: Object-oriented analysis and design: Grady Booch

approach. Object-oriented modeling and design: Jim Rumbaugh Object-oriented SE, A use case drive approach:

Jacobson

A modeling language provides:

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Seven goals of UML

Ready-to-use, expressive visual modeling language that promotes development/exchange

Extensibility/specialization of core concepts Independent of programming languages and

development processes Formal basis for understanding language Encourage growth of OO tools market Support higher level design concepts:

Collaborations, frameworks, etc. Collaborations, frameworks, ptterns, etc.

Integrate the best practices of all OOD

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Characteristics of UML

Generic syntax: Syntax is independent of:

Flexible syntax:

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UML modeling constructs/diagrams

User interaction diagrams Use-case diagrams

Static structure diagrams Class diagrams Object diagrams

Behavior diagrams Statechart diagrams Activity diagrams

Interaction diagrams Sequence diagram Collaboration diagram

Implementation diagrams Component diagram Deployment diagram

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Class diagrams

Class in UML:

Representation of classes:

Designer develops classes as sets of compartments that grow over time to incrementally add functionality and features

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Example class diagram

CustomerAccount

+ Account: Int+ Name: String+ Address: String+ Balance: Float

+ AddCustomer()+ DeleteCustomer()+ GetBalance()

Name

Attributes

Operations

“+” indicates that the attribute/operation is public“-” indicates that the attribute/operation is private“#” indicates that the attribute/operation is protected

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Relationships among classes

Inheritance Association Aggregation

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Generalization/Specialization (Inheritance)

BankAccount

CheckAccount SavAccount

Checking Account and Savings Account are special cases of Bank Account

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Generalization/Specialization (Inheritance)

Employee

Admin_staff Tech_staff

Administrative Staff and Technical Staff are special cases of the class Employee

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Association

Course1 *Instructor

Multiplicity constraints indicate how many objects participate in the association.May be specified as -- upper_bound….lower_bound1, 1:1 – Only one object*, 1:* - At least one object* -- any number of objects between 0 and infinity

Relationship among instances of objects of one class and instances of objects among other classes. Represent using a line, label each end With how many objects participate in the association.

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Association (contd..)

Multiplicity 1:3 indicates that each Instructor teaches at least one coursebut no more than three courses.

Course1 1:3Instructor

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Association (contd..)

* 1TechStaff

Manager

1

Project

1…*

project_member

manages

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Aggregation

Store Depts. 5

Objects are composed of simpler objects.

Triangle consists of three points.

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Class Diagram: High Tech SuperMarket System

Consider the process of updating the inventory in the high-tech supermarket system. Central to the process is an inventory order. An inventory assistant in the HTSS is responsible for managing a inventory order. In addition, each inventory assistant may be involved in managing several inventory orders. An inventory order is associated with a list of items. Each item in the list can be of three types, namely, snack item, liquor item, and canned item. Each inventory order is submitted to three wholesale stores. Each wholesale store caters to a specific set of items. For example, the Liquor Store is responsible for delivering liquor items. These three wholesale stores, are, namely, Liquor Store, Produce Store, and Snack Store. Construct a UML class diagram to model the process of inventory update in the HTSS.

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Class diagram: HTSS

InvenOrderInvenAssist

WholeStore ItemList Item

LiqStore ProdStore SnStore PerishItem NPerishItem

1 *

*1

1

11…3

1

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UML tools

Argo UML http://argouml.tigris.org

Object Domain http://www.objectdomain.com/domain/evaluationIntro.html

Rational Rose: http://www.rational.com

Microsoft Visio