Software Re-Engineering

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Software Re-Engineering

• Rebuilding the Wheel

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Software Reengineering (Context)
Software Maintenance
Adaptive
Corrective
Perfective
Reengineering

• Software reengineering is a part of software
  maintenance
• Corrective e.g., fixes
• Adaptive modifications to continue operation
• Perfective a.k.a. enhancement, addition of
  capability
• Reengineering rebuilding (may include elements
  of all former mx. types, but the intent is to
  rebuild to get a better program)

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Two Levels of Re-Engineering
Business Definition

• Business Level Business Process Re-engineering
• Software Level Software Re-Engineering

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Business Process Reengineering

• Business Definition Goals identified in
  business context. We exist to .
• Process Identification How do we achieve our
  goals
• Process Evaluation How good are these processes
• Process Specification and Design More formal
  descriptions of all a process entails
• Prototyping Testing a new process
• Refinement and instantiation Adjustments and
  implementation

Business Definition
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Software Reengineering

• Inventory Analysis What applications, what
  kind, what .
• Document Restructuring How good is an app
  documented? How good should it be?
• Reverse Engineering Abstraction
  recoverydesign, data model, arch. Model.
• Code Restructuring Improving the clarity or
  maintainability of app code.
• Data Restructuring Analogous actions as code
  restructuring on the data (e.g., converting local
  implementations to standard data structures.
• Forward Engineering Uses the info from reverse
  engineering to improve app at a higher
  abstraction than the data or program structure

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Reverse Engineering Details

• Purpose To generate an higher-level abstraction
  from the source code (or executable)
• Attributes
• Completeness how much detail exists in the
  abstraction
• Interactivity how much human intervention is
  required to create the abstraction
• Directionality Output only (one-way) or
  input/output (two-way)

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Why/Why Not Reengineer?

• Why Not?
• What we have works
• Cost (time, money, manpower, projects)
• Why?
• Foundational to business
• Potential (revenue, cost reduction, decrease
  effort)
• It no longer works, or works well

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Popular Reengineering Activities

• Business Processes
• User Interfaces
• Client/Server Architectures
• Databases

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Additional Points of Emphasis

• BPR focuses on individual or sub- processes due
  to risk (pg 839)
• Ways to attack re-documenting (pg 844)
• Dont do it
• Only when touched
• Full effort
• Data name rationalization (pg 851)
• Suggestions for reengineering user interfaces (pg
  855)
• Cost model for reengineering (pgs 855-856)