Introduction to Software Engineering

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Introduction to Software Engineering

• Chris Murphy
• Programming Systems Lab

2
How many lines of code?

• Average CS1004 assignment
• 200 lines
• Average CS4115 project
• 5000 lines
• Corporate e-commerce project
• 80,000 lines
• Microsoft Windows XP
• 40,000,000 lines

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What is Software Engineering?

• The practice of creating and maintaining
  software applications by applying technologies
  and practices from engineering, computer science,
  project management, application domains and other
  fields.
• -Wikipedia

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Over 50 of software projects fail

• Fred Brooks IBMs OS/360 was late, took more
  memory than was planned, costs were several times
  the estimate, and it did not perform very well
  until several releases after the first

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Why do software projects fail?
Difficult to accurately estimate how long
something will take
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Why do software projects fail?
Developers typically overestimate/overstate their
productivity
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Why do software projects fail?
Requirements are not always clearly defined
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Why do software projects fail?
Requirements are not always realistic
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Why do software projects fail?
Requirements are always changing
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Software development tradeoffs

• Cost vs Scope vs Quality vs Time
• Security vs Performance
• Specialization vs Generalization
• Specificity vs Flexibility

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Software Engineering

• Processes
• Project management (resources, time, etc.)
• Requirements gathering management
• Software design architecture
• Software development
• Testing and quality assurance
• Tools
• Software design, development, and testing
• Communication
• Requirements and defect tracking
• Version control

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Software Engineering

• Processes
• Project management (resources, time, etc.)
• Requirements gathering management
• Software design architecture
• Software development
• Testing and quality assurance
• Tools
• Software design, development, and testing
• Communication
• Requirements and defect tracking
• Version control

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Software testing is undervalued

• Software and Cathedrals are much the same
  First we build them, then we pray!!!
• -Sam Redwine, Jr.

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Software testing is important
Half of the time in the software development
cycle is spent on testing
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Types of software testing

• Unit testing
• Test the basic pieces, eg methods or functions
• Integration testing
• Combinations of units
• System testing
• Black-box or acceptance testing
• Regression testing
• Make sure changes dont break anything
• Non-functional testing
• Performance, security, etc.

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Other types of testing

• Obsession testing
• Ill fix this bug if its the last thing I do.
• Aggression testing
• If this doesnt work, Im gonna kill somebody.
• Depression testing
• If this doesnt work, Im gonna kill myself.

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My research

• In vivo testing
• Executing tests in the field while the software
  is running
• Testing machine learning applications
• Looking for ways to test when the correct outcome
  cannot be known in advance
• Retina
• Learning about CS1 students programming habits
• genSpace
• Collaboration in computational biology
• cmurphy_at_cs.columbia.edu