Development HIMS 650

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Back to SDLC

Two Kinds of Development

§ Waterfall – more traditional, take more time to get “everything right” before moving to next phase

§  Agile – Embrace uncertainty. Build now, build often, fix later.

Waterfall

§  Comes from traditional manufacturing tradition §  Plan – Do – Check – Act §  Get to stability in given phase, then freeze

§  Lack of “freeze discipline” introduces enormous risk §  Take the time to get each phase “just right”

§  Phases measured in weeks (rarely) or months (common)

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Waterfall Process

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Waterfall Process

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“Can’t go up a waterfall”

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Waterfall - How to minimize errors? “… it costs 100 times more to find and fix a problem after software delivery than to find and fix it in early design phases”

Develop

Design

“… so freeze your design earlier to make sure that you’ve figured everything out before you go on”

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How to minimize errors? … but does it make sense in the development phase, too?

Develop

Design

Actually, the auto industry does this a different way

In fact, they’re doing this a different way, too, now!

Agile Process

§  Borrowed some ideas from Lean §  Be able to accommodate changing demands §  Make decisions as late as possible §  Reduce time to deliver (days to weeks, not weeks to

months) §  Made up some ideas of their own

§  Don’t define in great detail up front

§  Test-driven processing §  “Scrum” mentality

§  Paired programming §  Stakeholders involved

continuously

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Agile Process

Discover Define Design Develop

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Agile Process

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Release 1 Release 2 Release 3

“… it costs 100 times more to find and fix a problem after software delivery than to find and fix it in early design phases”

“… so you need to iterate like crazy before you finally release, and you need to make it cheaper to discover problems after development”

§  Split into 4 teams

§  One person will be Quality Control §  Count defects §  Determine developer that

needs to fix it §  Advise developer what

needs to be fixed

User-centered with Agile – LEGO approach

§  Understand the needs of your userbase – do the research and homework!

§  Iterate like crazy through design alternatives §  Once you’ve decided you like it, freeze the design

§  Document it like LEGO’s (a picture of what needs to be built) in addition to words about how it works

§  If design needs to be altered in development, bring the team back together to determine alternative

§  Build the design, test it, redesign, rebuild, retest

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User-centered Design/Development – many possible approaches

Discover

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Discover Define

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Discover Define Design Develop

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