an introduction to xp and agile
Post on 17-Oct-2014
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An introduction to XP and Agile for SyXPACTRANSCRIPT
What’s the problem?
Software takes too long, costs too much, and requires
too many people
The plan is fantasy… and we don’t learn this until it’s too late
We’re wasting our lives doing things that don’t matter
Why do the problems occur?
We only have one opportunity to decide, so we ask for
everything… and we waste time building what we don’t actually
need
How often are features used?
We defer concrete validation until it’s too late to respond
We punish raising problems
We have too much specialisation
We have a “not my problem” culture
What do we want instead?
Any feature, any order, one at a time
Highest productivity, highest quality, lowest cost, highest
morale
Real visibility about what’s happening
Learn about problems as early as possible
Less administrative work; more value-adding work
XP and Agile as a solution
Philosophy, Process, People, Problem Solving
ProblemSolving
People
Process
Philosophy
Philosophy: Values
• Simplicity• Communication• Feedback• Courage• Respect
Software is too damned hard to spend time on things that don't matter. So, starting over from scratch, what are we absolutely certain matters?…Listening, Testing, Coding, Designing. That's all there is to software. Anyone who tells you different is selling something.
Kent Beck, http://www.c2.com/cgi/wiki?ExtremeProgramming
Process: Just-in-Time
User Stories
• AS an Agile team member, I WANT a way to have self-contained small units of work SO THAT I can focus on one thing at a time, show visible progress earlier, and allow for negotiation
Card, Conversation, Confirmation
• Card – index card; physical token used for visual planning and tracking
• Conversation – primary medium of communication supplemented as necessary with documentation
• Confirmation – Examples that indicate when story is complete; turned into automated tests
http://www.xprogramming.com/xpmag/expCardConversationConfirmation.htm
Timeboxed iterative-incremental development
Small Releases
http://www.slideshare.net/cching/rocks-into-gold-by-clarke-ching-presentation
Process: Built-in Quality
Mistake proofing
1. Eliminate – Don’t build it – YAGNI2. Replace – Use a reliable library3. Prevent by design4. Facilitate – Only use the useful
features, ignore the rest5. Detect as early as possible – TDD,
CI, pair programming6. Mitigate – Make sure problems
don’t cascade; error-handling
Test-driven Development
1. Think2. Red3. Green4. Refactor5. Repeat
http://jamesshore.com/Blog/Red-Green-Refactor.html
Continuous Integration
Pair Programming
People: T-shaped people
People: Whole Team
http://www.think-box.co.uk/blog/2007/11/theres-hole-in-your-side-of-boat.html
Authority vs Responsibility
Problem Solving: Daily Standups
• What did I accomplish yesterday?• What will I do today?• What obstacles are impeding my
progress?
http://martinfowler.com/articles/itsNotJustStandingUp.html
Problem Solving: Retrospectives
• What did we do well, that if we don’t discuss we might forget?
• What did we learn?• What should we do differently next
time?• What still puzzles us?
http://www.retrospectives.com/
Problem Solving: Spikes over speculation
"What is the simplest thing we can program that will convince us we are on the right track?“
Ward Cunningham
http://c2.com/xp/SpikeSolution.html
Why should we believe this will work?
This is the evolution of what we’ve learned over decades
“Although many view iterative and incremental development as a modern practice, its application dates as far back as the mid-1950s.”
Craig Larman and Victor R. Basili
http://www.cs.umd.edu/~basili/publications/journals/J90.pdf
Don’t believe… think for yourself… try something… see
what happens… adjust
For some more conventional introductions…
• http://www.extremeprogramming.org
• http://www.xprogramming.com/xpmag/whatisxp.htm
• http://www.agilemanifesto.org/• http://www.poppendieck.com/