Design Pattern Automation for ReEngineering

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Design Pattern Automation for Re-Engineering

• Paul Gestwicki and Fu-Shing Sun
• Ball State University
• New Proposal
• SERC Showcase
• December 6, 2007

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Outline

• Introduction to Design Patterns
• Pattern-Oriented Re-Engineering
• Proposed Research

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Design Patterns
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Design Patterns Defined
Each pattern describes a problem which occurs
over and over again in our environment, and then
describes the core of the solution to that
problem, in such a way that you can use this
solution a million times over, without ever doing
it the same way twice.
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Design Patterns in Software
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Major Benefits ofPattern-Orientation

• Facilitates object-oriented design and analysis
• Improves reusability
• Improves software maintenance
• Increase software comprehension
• Reduce training costs

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Example State Machines
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Naïve Implementation
const int ACCEPTING_INPUT 1 const int
PROCESSING 2 int state ... void
handleInput() switch (state) case
ACCEPTING_INPUT ... case PROCESSING
... void handleWindowClosed() switch
(state) case ACCEPTING_INPUT ... case
PROCESSING ...
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Pattern-Oriented Design
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Outline

• Introduction to Design Patterns
• Pattern-Oriented Re-Engineering
• Proposed Research

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Re-Engineering

• May include refactoring or redesign
• A combination of
• Reverse engineering legacy systems
• Forward engineering new systems

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Forward Engineering

• Requirements-driven development
• Adopt patterns based on
• Requirements
• Domain
• Expertise

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Forward Engineering Example
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Object-Oriented Solution
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Pattern-Oriented Solution
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Reverse Engineering

• Understand an unfamiliar system
• Identify patterns
• Limited tool support exists

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Tool-Supported Pattern Recovery

• State-of-the-art tools
• FUJABA, DP-Miner, Borland Together
• Structural, behavioral, and semantic analysis
• Machine learning approaches

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Sample Pattern Recovery

• JHotDraw 6.0 beta 1
• 530 classes in 484 files
• Tool-supported pattern recovery found
• 4 adapters, 58 bridges, 64 strategies
• JEdit 4.2
• 1001 classes in 394 files
• Tool-supported pattern recovery found
• 17 adapters, 24 bridges, 24 strategies

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Observations

• Design patterns are not formulas
• Reification depends on language, idioms, style
• Strategy, Adapter, and Bridge
• Naïve implementations are obvious
• Clever implementations are subtle... and
  therefore difficult to detect

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Outline

• Introduction to Design Patterns
• Pattern-Oriented Re-Engineering
• Proposed Research

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Long-Term Goal

• Automated pattern recommendations based on formal
  requirements
• An expert system for pattern-oriented software

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Short-Term Goal

• Given a legacy system
• Predict patterns through requirements analysis
• Detect patterns through reverse-engineering
• Result
• Pattern-oriented software analysis
• Useful for refactoring or redesign

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Major Challenges

• Lack of design documentation
• Pattern reification and language idioms
• Imprecise or nondeterministic recovery
• False positive and true-negative
• Manual verification is error-prone

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Proposed Deliverables

• Comprehensive analysis of an existing system
• Pattern analysis (reverse engineering)?
• Pattern recommendations (forward engineering)?
• Details of the research methodology
• Recommendations for automation

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Budget and Contact Information
Proposed budget 26,000 Project duration One
year Paul Gestwicki pvgestwicki_at_bsu.edu Fu-Shi
ng Sun fsun_at_bsu.edu http//www.cs.bsu.edu/pvg
/patterns