Software Design: The Next Step

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Software Design The Next Step

• A presentation by Sean Matthews

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Kruchen, P. 2005. "Editor's Introduction
Software Design in a Postmodern Era." Software,
IEEE 22 (2) 16-18.
Kruchten, P. 2005. "Casting software design in
thefunction-behavior-structure framework."
Software, IEEE 22 (2) 52-58.
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Intro

• Weve reached a plateau in software design
• What are the next directions?
• Where are we?
• Where do we go from here?

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Where are we?

• we can systematically harvest and organize our
  collective knowledge, experience, and wisdom
  variously captured in design principles and
  heuristics, patterns, best practices, and bad
  smells into a coherent whole.

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Where do we go from here?

• We need to
• Bridge the gap between user needs and the way we
  express requirements
• Improve design analysis, validation, and
  verification techniques
• Bridge the gap between design and code that
  programmers create manually

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Requirements Engineering
GAP
Design
GAP
Coding
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Where do we go from here?

• Expand the boundaries of software design to fill
  in the gaps
• When we program and test, were making decisions
  about the system under construction this is
  doing design.
• Design activities should be included in other
  parts of the software development process

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Analogous situations

• To demonstrate how and why design should be
  combined with other phases of the SD process, the
  author casts it in a general, recently formulated
  engineering framework.

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Functional-Behavior-Structure

• A development framework applicable to any
  engineering discipline
• John Gero, design scientist
• 8 processes link a set of five elements that lead
  us from a set of abstract functions to a design
  description

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Functional-Behavior-Structure

• FBS Elements
• F functions
• Be expected behaviors
• Bs behaviors (actual)
• S synthesis
• D documentation

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Functional-Behavior-Structure

• FBS Processes
• Formulation (F ? Be)
• Synthesis (Be ? S)
• Analysis (S ? Bs)
• Evaluation (Be ? Bs)
• Documentation (S ? D)
• Structural reformulation (S ? S)
• Behavioral reformulation (S ? Be)
• Functional reformulation (S ? F)

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FBS Framework
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Applying FBS to SE

• design is making choices that will shape the
  final product.
• Requirements, coding, and testing activities all
  involve some design
• Traditionally, design means building a model of
  the system to be constructed up to the point at
  which coding can begin.

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Applying FBS to SE
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Applying FBS to SE
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SE lessons from FBS

• Lack of fundamental theory
• Physics has its laws
• Evaluation process is experimental
• Concrete S, almost no addition to D

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SE lessons from FBS

• Legacy systems
• D ? S ? Be ? F
• Reuse
• F ? Be ? S
• catalogue look-up

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SE lessons from FBS

• Modeling
• to automate the coding and deployment artifacts
• to describe a systems expected behavior (Be),
  and thereby facilitate the synthesis (S) process

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SE lessons from FBS

• Design patterns
• If F1 and Bs1 F2 and Bs2, then the designs
  are analogous
• We can communicate design fragments and share and
  reuse practical solutions for recurrent problems.

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The BIG picture

• In software production, programming is primarily
  a design activity
• In software manufacturing it is not
• Decisions about structure and the way something
  is done
• Also, testing to a smaller extent
• Assessment of test results determine whether
  design needs reworking

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Conclusions

• Generally, something gets lost between design and
  implementation.
• With FBS, design becomes part of coding and
  implementation.
• SE needs to find approaches to describing
  software that easily translate to static analysis
  and code generation.

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References
Kruchen, P. 2005. "Editor's Introduction
Software Design in a Postmodern Era." Software,
IEEE 22 (2) 16-18.
Kruchten, P. 2005. "Casting software design in
thefunction-behavior-structure framework."
Software, IEEE 22 (2) 52-58.