PROGRAMVARUKONSTRUKTION Software Engineering

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PROGRAMVARUKONSTRUKTION(Software Engineering)

• Introduktion
• VT04

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• Building software will always be hard. There is
  inherently no silver bullet.
• F.P. Brooks, Jr.

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Process?
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Krav, prototyper och modellering

• Requirements engineering is more difficult now,
  because all systems that were easy to specify
  have been built some time ago.
• T. DeMarco
• Requirements deficiences are the prime source of
  project failures.
• Robert Glass
• Errors are most frequent during the requirements
  and design activities and are more expensive the
  later they are removed.
• Barry Boehm

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Krav, prototyper och modellering

• Prototyping (significantly) reduces requirement
  and design errors, especially for user
  interfaces.
• Barry Boehm
• The value of a model depends on the view taken,
  but none is best for all purposes.
• Alan Davis
• Object model reduces communication problems
  between analysts and users.
• Grady Booch
• Short-term memory is limited to 72 chunks of
  information.
• George Miller

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Systemdesign och systemspecificering

• Good designs require deep application
  knowledge.
• Bill Curtis
• Hierarchical structures reduce complexity.
• Herb Simon
• A structure is stable if cohesion is strong and
  coupling low.
• Larry Constantine
• Formal methods significantly reduce errors, or
  eliminate the early.
• Heinz Zemanek

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Implementation av system

• What applies to small systems does not apply to
  large ones.
• DeRemer
• Well-structured programs have fewer erors and
  are easier to maintain.
• Dijkstra, Mills och Wirth

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Verifiering och validering

• Inspections significantly increase productivity,
  quality, and project stability
• Michael Fagan
• A combination of different VV methods
  outperforms any single method alone.
• Glen Myers
• Testing can show the presence but not the
  absence of errors.
• Edsger Dijkstra
• A developer is unsuited to test his or her
  code.
• Weinberg

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Systemunderhåll och användning

• A system that is used will be changed.
• An evolving system increases its complexity
  unless work is done to reduce it
• Manny Lehman

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Projektledning av programvaruprojekt

• Most cost estimates tend to be too low.
• Tom DeMarco Robert Glas
• Mature processes and personal discipline enhance
  planning, increase productivity and reduce
  errors.
• Watts S. Humphrey
• Adding manpower to a late project makes it
  later.
• Fred Brooks