COMP 6471 Software Design Methodologies

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COMP 6471Software Design Methodologies

• Winter 2006
• Dr Greg Butler
• http//www.cs.concordia.ca/gregb/home/comp647-win
  ter2006.html

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Course Introduction

• Course People
• Course Components
• What the course is
• What the course is not
• The CU WME Design Case Study
• Larmans Design Process
• What is OO Analysis and Design
• Design Pattern Example - Command

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Course People

• Instructor Dr Greg Butler
• Office Hours Wednesdays 1600 to 1700
• Or by appointment
• But ask questions in class please
• TAs Bahman Zamani, Farzad Kohantorabi
• Teaching Fellow Stephen Barrett
• Labs Wednesday 1530 to 1730 ???

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Course Components

• Lectures Mondays 1745 to 2025 H-603-1
• Assignments 6, every 2 weeks, worth 60
• Quizzes 2, weeks 6 and 12, worth 40
• You must pass the quizzes!!!

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Course Objectives

• Think in Objects
• Analyze requirements with use cases
• Create domain models
• Apply an iterative agile Unified Process (UP)
• Relate analysis and design artifacts
• Read write high-frequency UML

• Practice
• Apply agile modeling
• Design object solutions
• Assign responsibilities to objects
• Design collaborations
• Design with patterns
• Design with architectural layers
• Understand OOP (e.g., Java) mapping issues

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What the course is

• A (first) look at OO design!
• Design process domain model, use cases, design
• Emphasis models, GRASP principles, design
  patterns, responsibility, collaboration
• Mentions RDD, TDD, MDD, extensibility
• Closely follows textbook!

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What the course is not

• A course in UML, Java
• You should know the basics of these
• And become expert (as needed) yourself
• A course in tools Eclipse, XDE, JUnit
• You can work through tutorials yourself
• A course in UI design, DB design
• A course in software engineering, software
  architecture, software reuse,

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The CU WME Design Case Study

• Concordia University Work Management Environment
  (CU WME) provides support for an organisation of
  people who produce and publish documents
• Components
• User Management
• File Management
• Change Management
• Activity Management
• Collaborative Publication
• Project Management

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The CU WME Design Case Study

• No UI required
• No DB design required
• But we design APIs to hide these
• Assignments
• Short problem statement
• Domain model
• Use case model
• Design and code (proof-of-concept)
• Refinement add some special cases
• Refinement handle some exceptions

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The CU WME Design Case Study

• Team of up to six members preferably 5 or 6
• Individual work on individual component of CU WME
• Rotate responsibility for components
• Components must be consistent
• Therefore teamwork essential

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Larmans Design Process
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Domain Model
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Use Case Model
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Typical Software Architecture Layers
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Typical Software Architecture Layers (Simplified)
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What is Design?

• Developing a blueprint (plan) for a mechanism
  that performs the required task,
• taking into account all the constraints,
• making trade-offs between constraints when they
  are in conflict.

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What is OO Analysis and Design

• Object-Oriented Design
• Design of software objects
• Responsibilities
• Collaborations
• Design patterns
• Visualized in the UP Design Model

• Object-Oriented Analysis
• Important domain concepts or objects?
• Vocabulary?
• Visualized in the UP Domain Model

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Important Concepts

• Model
• Abstraction hiding (unimportant) details
• Eg, cover of Larmans book
• GRASP Principle
• for assigning responsibility
• Design pattern
• Solution to design problem in context
• Eg, Command pattern

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Responsibility-Driven Design (RDD)

• Detailed object design is usually done from the
  point of view of the metaphor of
• Objects have responsibilities
• Objects collaborate
• Responsibilities are an abstraction.
• The responsibility for persistence.
• Large-grained responsibility.
• The responsibility for the sales tax calculation.
• More fine-grained responsibility.

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The 9 GRASP Principles

1. Creator
2. Expert
3. Controller
4. Low Coupling
5. High Cohesion
6. Polymorphism
7. Pure Fabrication
8. Indirection
9. Protected Variations

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Overview of Patterns
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Command Pattern

• You have commands that need to be
• executed,
• undone, or
• queued
• Command design pattern separates
• Receiver from Invoker from Commands
• All commands derive from Command and implement
  do(), undo(), and redo()
• Also allows recording history, replay