Embracing Change with Extreme Programming

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Embracing Changewith ExtremeProgramming

• By Kent Beck

Presented by Josh Horner
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Traditional Project Management Method

• Waterfall method
• Works when the customers
• Know exactly what they want
• Dont change their minds
• Dont contradict themselves
• Downfall
• Long development
• cycle
• testing at end
• ?oops

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Why Waterfall?

• Broad software changes
• Increased as life cycle progresses
• Somajor decisions made early

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Shorter Development Cycle

• But new technology (relational databases, modular
  programming, information hiding) reduces cost
• Iterative
• Method

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Extreme Programming (XP) Practices

• Planning Game
• Small Releases
• Metaphor
• Simple Design
• Tests
• Refactoring

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Extreme Programming (XP) Practices (cont.)

• Pair Programming
• Continuous Integration
• Collective Ownership
• On-site Customer
• 40-hour Weeks
• Open Workspace
• Just Rules

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Development Cycle
Stories
Release
Iteration
Tasks
Tests
Program
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Timeframe
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Stories

• Requirements
• Start with a bare-bones feature set
• Story (feature)
• Business-oriented
• Testable
• Estimable

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Release

• Customer picks the smallest set of most valuable
  stories
• Implement
• Repeat with additional stories
• Metaphor Grocery Shopping
• Items stories
• Prices estimates from team
• Budget then pick items?

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Iteration

• Process
• Plan implementation
• Task Division Estimation
• Programmer Implement
• Integrate Test (unit test)
• Customer deliver functional tests
• Add tests
• Run all unit functional tests

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Task

• Questions? Brief meeting with customer
• Pair Programming
• Process
• Pick a test case to implement
• Code
• Test
• On failure,
• Find clean solution
• Find dirty solution, redesign (refactor)
• Find dirty solution, keep

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Test Unit Tests

• Test everything that can break
• Unconventional
• Tests before code
• Written by programmer
• Programming ? learning ? quick feedback
• Not test written by someone else days after
  coding
• Tests permanent
• Automated
• Gain confidence in behavior over time

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Test Functional Tests

• System-wide test
• Black Box, expected value
• Builds customer confidence
• Update now Acceptance Tests1

1 lthttp//www.extremeprogramming.org/rules/functio
naltests.htmlgt
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OopsWhen Something Goes Wrong

• Underestimation
• Practice estimating
• Overcommitted Are you following XP practices
  correctly?
• Re-estimate and talk to customer
• Uncooperative Customer
• Does not specify tests, prioritize, write stories
• Cant guess. Ask for help

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OopsWhen Something Goes Wrong

• Turnover
• Pair programming
• New person catch up to speed
• Paired with veteran
• Read tests
• Talk to customer
• XP not for everyone

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OopsWhen Something Goes Wrong

• Changing Requirements
• Less planning is best
• pick stories for current iteration only
• If new story arises, add to pile
• If still urgent, customer will pick it

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XP in Use

• Acxiom campaign management database
• OO development tool, then XP
• DaimlerChrysler C3 payroll system
• First full XP project
• Before GUI-centered eye candy. Bad math
• After success
• Ford Motor VCAPS cost analysis system
• XP met volatile requirements

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Try XP?

• Slow adoption
• Worst problem in current process

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Websites

• http//www.extremeprogramming.org/
• http//www.xprogramming.com
• http//c2.com/cgi/wiki?ExtremeProgrammingRoadmap