An Introduction to XP and Agile Jason Yip, [email_address] http:// www.thoughtworks.com

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 Problem Solving People Process Philosophy

Philosophy: Values Simplicity Communication Feedback Courage Respect

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

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

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

Timeboxed iterative-incremental development

Small Releases http://www.slideshare.net/cching/rocks-into-gold-by-clarke-ching-presentation

Process: Built-in Quality

Mistake proofing Eliminate – Don’t build it – YAGNI Replace – Use a reliable library Prevent by design Facilitate – Only use the useful features, ignore the rest Detect as early as possible – TDD, CI, pair programming Mitigate – Make sure problems don’t cascade; error-handling

Eliminate – Don’t build it – YAGNI

Replace – Use a reliable library

Prevent by design

Facilitate – Only use the useful features, ignore the rest

Detect as early as possible – TDD, CI, pair programming

Mitigate – Make sure problems don’t cascade; error-handling

Test-driven Development Think Red Green Refactor Repeat http://jamesshore.com/Blog/Red-Green-Refactor.html

Think

Red

Green

Refactor

Repeat

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

What did I accomplish yesterday?

What will I do today?

What obstacles are impeding my progress?

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 /

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?

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

"What is the simplest thing we can program that will convince us we are on the right track?“

Ward Cunningham

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

“ 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

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 /

http://www.extremeprogramming.org

http://www.xprogramming.com/xpmag/whatisxp.htm

http://www.agilemanifesto.org/

http:// www.poppendieck.com /