Agile Methods and Extreme Programming

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Agile Methods andExtreme Programming
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Spectrum of Methods
Source "Get ready for agile methods, with care"
by Barry Boehm, IEEE Computer, January 2002.
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Agile Manifesto

• We are uncovering better ways of developing
  software by doing it and helping others do it.
  Through this work we have come to value
• Individuals and interactions over processes and
  tools
• Working software over comprehensive documentation
• Customer collaboration over contract negotiation
• Responding to change over following a plan
• That is, while there is value in the items on the
  right, we value the items on the left more.

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Some Agile Methods

• ASD - Adaptive Software Development
• Crystal
• FDD - Feature Driven Development
• DSDM - Dynamic Systems Development Method
• Lean Software Development
• Scrum
• XP - eXtreme Programming

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II. Extreme Programming
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Motivation

• Knobs on a control board
• Each knob a practice that works well
• Turn all knobs up to 10

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Learning to Drive

• "Driving is not about getting the car going in
  the right direction.
• Driving is about constantly paying attention,
  making a little correction this way, a little
  correction that way."
• -- Kent Beck, Extreme Programming Explained

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Four Values

• Simplicity
• create the simplest thing that could work
• Communication
• face-to-face, not document-to-face
• Feedback
• lots of tests
• Aggressiveness

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Four Basic Activities

• Coding
• cannot do without it
• Testing
• if it cannot be tested it doesn't exist
• Listening
• to those with domain knowledge
• Designing
• to keep the system from decaying

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Twelve Practices

• Pair programming
• Collective ownership
• Continuous integration
• 40-hour week
• On-site customer
• Coding standards

• The Planning Game
• Small releases
• Metaphor
• Simple design
• Testing
• Refactoring

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1. The Planning Game

• Business people decide
• scope
• priority
• release dates
• Technical people decide
• estimates of effort
• technical consequences
• process
• detailed scheduling

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2. Small Releases

• Every release should be as small as possible
• Every release has to completely implement its new
  features

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Waterfall to XP Evolution
Source "Embracing change with extreme
programming" by Kent Beck,IEEE Computer, October
1999.
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3. Metaphor

• Each XP project has its own metaphor
• naive
• system is a spreadsheet
• Metaphor replaces architecture as the view from
  10,000 feet

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4. Simple Design

• Runs all the tests
• Has no duplicated logic
• States every intention important to programmers
• Has the fewest possible classes and methods

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5. Testing

• Any feature without an automated test does not
  exist.
• Programmers need confidence in correct operation
• Customers need confidence in correct operation

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6. Refactoring

• Always ask if there is a way to make the program
  simpler
• When the system requires duplication of code, it
  is asking for refactoring
• Can always find a series of small, low-risk steps

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7. Pair Programming

• All code written with 2 people at one machine
• Driver
• thinks about best way to implement
• Passenger
• thinks about viability of whole approach
• thinks of new tests
• thinks of simpler ways

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8. Collective Ownership

• Anybody who sees an opportunity to add value to
  any portion of the code is required to do so
• Everyone knows something about everything
• Everyone feels obligated to make improvements

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9. Continuous Integration

• Integrate and test every few hours, at least once
  per day
• All tests must pass
• Easy to tell who broke the code

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10. 40-Hour Week

• People should be fresh and eager every morning
• Overtime is a symptom of a serious problem
• XP only allows one week of overtime

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11. On-Site Customer

• Real customer will use the finished system
• Programmers need to ask questions of a real
  customer
• Customer can get some other work done while
  sitting with programmers

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12. Coding Standards

• Everyone edits everyone's code
• Standard should require least amount of overhead
• Standard should be adopted voluntarily by the team