Advanced Object-Oriented Design Patterns and Architectures Part One

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Advanced Object-Oriented Design Patterns and
Architectures Part One

• COEN396A
• John Xiao
• cunxiao_at_us.ibm.com

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Motivations

• Its difficult to write good software
• Its really difficult to write good, reusable
  software
• Where has OO failed to deliver?
• where are the big success stories?

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Course Home Page

• Information available at www.cse.scu.edu/jxiao1/
• Course description
• Schedule
• Homeworks
• Handouts
• Patterns Project

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Course Description

• Three primary topics
• design patterns
• frameworks
• component-based software engineering
• Advanced OO reuse constructs
• Design
• Implementation
• References at www.cse.scu.edu/jxiao1

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Prerequisites

• Object-oriented analysis and design (Booch,
  Rumbaugh, Jacobson, UML)
• Object-oriented programming (C, Java)

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Patterns Project

• Team-oriented
• Pick pattern(s)
• Implementation in Java (Beans)

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Patterns Project

• 30 minute class presentation
• demo the pattern/discuss issues
• Prepare homework assignment
• concrete design/implementation
• reflective component
• Web page
• summary, details, links to info
• Review
• review other teams

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Possible Groupings

• observer,mediator
• abstract factory,building,factory method
• prototype,singleton,flyweight
• adapter,bridge,decorator
• façade,interpreter
• state,strategy,template method
• composite,iterator,visitor
• command,interpreter
• OR
• memento, serialization
• visitor critiques

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Deliverables

• Presentation
• Assignment
• Assignment Solution
• Web page
• Review

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Deadlines

• See Syllabus

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Patterns of Learning

• Successful solutions to human endeavors are often
  rooted in patterns
• Example becoming a chess master
• first learn the rules and physical requirements
  (pieces, legal moves, board layout, etc)
• then learn principles (relative value of pieces,
  value of center squares, etc)
• to become master study games of other masters
• memorize their playing patterns
• there are hundreds/thousands of patterns

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Becoming a software design master

• first learn the rules (algorithms, data
  structures, languages)
• then learn principles (structured programming,
  object-oriented programming, functional
  programming)
• to become master study designs of other masters
• memorize their designing patterns, apply them
  repeatedly
• there are hundreds/thousands of patterns

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OOA Review

• OOA
• Requirement Analysis
• Use Cases/Use Case Diagrams
• High-level vs. expanded
• Essential vs. real
• Conceptual Model/Class Diagrams
• Concepts/Classes
• Attributes
• Associations/Associative Type
• Aggregation(Composite/Shared)
• Generalization
• System Sequence Diagrams
• Contracts

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OOD Review

• OOD
• Interaction Diagrams (e.g. Collaboration
  Diagrams) (from real use cases)
• Design patterns
• Visibility (attribute/parameter/local/global)
• Design Class Diagrams
• Interfaces
• Methods
• Navigability
• Attributes type info

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Design level reuse szyperski

• Sharing consistency programming languages
• Sharing concrete solution fragments libraries
• Sharing individual contracts interfaces
• Sharing individual interaction architectures
  patterns
• Sharing architectures frameworks
• Sharing overall structure system architectures
• Systems of subsystems framework hierarchies

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Patterns vs Frameworks vs Components

• patterns support reuse of software architecture
  and design
• capture static and dynamic structure and
  collaborations of successful solutions to common
  problems
• frameworks/components support reuse of detailed
  design and code
• an integrated set of software constructs that
  collaborate to provide a reusable architecture
  for a family of related applications

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Design Patterns

• Gamma, Helm, Johnson, Vlissides (GOF)
• Studied super programmers
• Catalogued patterns
• Design patterns solve problems that are
• in every single program you will ever write
• Generic problem/Generic solution
• Specific problem/customization of generic solution

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What is a pattern?

• Description of a problem/solution pair in a
  certain context
• Originate from architecture
• Christopher Alexander 1977
• Explicit design expertise and experience
• Designing a house versus designing a program
• Building a house versus building a program

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Pattern Format

• Format
• Name
• Context
• Problem
• Solution
• .
• Kinds
• architectural (overall description)
• design patterns (design problems)
• idioms (language specific)

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Example Singleton

• See book

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Patterns Review

• Expert
• Creator
• Controller
• Low Coupling
• High Cohesion
• Polymorphism
• Pure Fabrication
• Indirection
• Law of Demeter