Chapter 2 Systems Development and the Software Crisis

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Chapter 2Systems Development and the Software
Crisis

• ?Brief History
• ?Need for a New Approach
• ?Costs and Benefits of Objects

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? Brief History

• 1950s and 1960s, Systems Analysis was
  unstructured, unorganized
• It was not done well.
• Over the last 30 years we have made many
  improvements
• But software still has just as many bugs!
• But back then a large project was a few thousand
  lines of code
• Nowadays large means several million lines of
  code.

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? Brief History

• Maintenance changes have always been a problem.

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? Brief History

• Backlogs (jobs undone)
• At any time there has been about a 5-year backlog
• Plus there has also been a 5-year invisible
  backlog (all the requests that our users didnt
  bother to make because of the visible backlog).
• This has had two effects
• A move to end-user computing
• A constant search for better ways to develop
  software systems.

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? Brief History

• Reliability
• What caused all the maintenance and backlogs?
• Poor initial design led to problems of
• Flexibility, the ability of a system to handle
  unforeseen events or transactions
• Resilience, the ability to handle changes during
  maintenance without other problems happening with
  every little change.
• Quality

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? Need for a New Approach to Systems Development

• Many business managers do not realize how complex
  software development can be
• Many use amateurs and hackers
• Others hire out-of-date professionals
• There are good ways and bad ways to do it
• Good consultants are expensive
• Because thats what they are worth in ROI
  (Return on Investment)

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? Costs and Benefits of Objects

• Benefits of Objects (OO techniques)
• System Stability (resilience to change)
• Maintainability
• Reusable software components
• Reality-based systems
• Data accessibility
• User involvement and ownership

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? Costs and Benefits of Objects

• Costs of Objects
• Installed software base
• COBOL
• Legacy Systems Out-of-date systems that already
  exist and must continue to exist for the
  foreseeable future.
• Retraining
• Not just a new language, but
• A whole new way of thinking
• Need a carefully-planned conversion
• See Chapter 15, Moving to O-O Techniques

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End of Chapter 2.