Technical debt

SCRUM & TECHNICAL DEBT CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 1

Joe Little• Agile Coach & Trainer• 20+ years in senior level consulting to well-known ﬁrms in New York, London and Charlotte• Focus on delivery of Business Value; interest in Lean• CST, CSP, CSM; MBA• Was Senior Manager in Big 6 consulting• Head of Kitty Hawk Consulting, Inc. since 1991• Head of LeanAgileTraining.com• Started trying to do [Agile] before reading The Mythical Man-Month – http://agileconsortium.blogspot.com – jhlittle@kittyhawkconsulting.com © Joe Little 2010 2

Customers want a qualityproduct quickly. © Joe Little 2010 3

What is technical debtHow would you notice it?A velocity that is based on a weak definition ofdone is just a lie!!!"Scrum made me go too fast!" NO!!!The bad news does not get better with ageHow do we explain technical debt to theproduct owner?How do we explain technical debt to themanagers? © Joe Little 2010 4

The importance of a definition of done inScrumThe importance of professionalism in ScrumThe importance of strong engineeringpractices in ScrumScrum assumes your engineering practices arenot "perfect"Why is Scrum only a framework?Some key engineering practices (mostly fromXP)Incentives © Joe Little 2010 5

Scrum Dynamic Model Daily Meeting Sprint I R M D P E E O A D N D I E M Value Y E Velocity N T S CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 6

Technical Debt is bad. Period.Very bad! © Joe Little 2010 7

What is Technical Debt?And why is it bad? (Very bad.) © Joe Little 2010 8

A velocity that allows technicaldebt to be built is a lie!A velocity that is built on aweak definition of done is a lie! © Joe Little 2010 9

“Scrum made us go too fast!”No! © Joe Little 2010 10

Definition of Done needed to split stories Default Definition of Done • Automated tests, built & runDefault Definition of Done • No bugs • Acceptance tested• Releasable • Release notes written • Releasable • No increased technical debt Default Definition of Done • Unit/Integration tested • Accepted by PO • Ready for acceptance test • Deployed on demo server = I haven’t made the codebase hard to change What’s NOT included in DoD? - Example: ”customer acceptance test + user documentation”? Why not? Who does it? When? What happens if a problem turns up? Source: Henrik Kniberg CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 11

Topic: Velocity & technical debt Queue theory Chaos theory Principles e arch Res Agile Lean Game theory History Philosophy More theory... m Scru XP Practices Implementation Company Company B Company A Company CSource: Henrik Kniberg C CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 12

Clean & simple Dog.java v1.1Dog.java v0 Dog.java v1.0 Big & hairy Quick & dirty import java.sql.Connection; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class Dog { public class Dog { private Executor executor = Executors.newFixedThreadPool(18); private int CACHE_SIZE = 50; public static void main(String[] args) { System.out.println("WOOF 1!"); public Dog() { System.out.println("WOOF 2!"); try { } Class.forName("oracle.jdbc.ThinDriver"); connection = DriverManager.getConnection("jdbc:oracle:thin:@prod", "admin", } "beefhead"); statement = connection.prepareStatement("insert into Dog values (?, ?, ?)"); } catch (ClassNotFoundException e) {} new Thread().start(); } public void woof(Person woofCaller) { Connection connection = null; PreparedStatement statement = null; try { connection = DriverManager.getConnection("jdbc:oracle:thin:@prod", "admin", Dog.java v1.2 "beefhead"); statement = connection.prepareStatement("insert into Dog values (?, ?, ?)"); statement.setLong(1, System.currentTimeMillis()); Clean & simple statement.setString(2, person.getName()); statement.setString(3, person.getPhoneNumber().getNumber()); statement.executeUpdate(); } } }public class Dog { } Connection a = DriverManager.getConnection("jdbc:oracle:thin:@prod", "admin", private final String name; Simple code: "beefhead"); b = a.prepareStatement("select * from Dog where name = " + name + ""); c = b.executeQuery(); private int woofCount = 0; 1.Passes all tests if (c.next()) { String foundName = c.getString("name"); PhoneNumber phoneNumber = new PhoneNumber(c.getString(“woofCount")); public Dog(String name) { 2.No duplication Person person = new Person(foundName, phoneNumber); return person; this.name = name; } else { } 3.Readable } return new Person("", null); public void woof() { 4.Minimal } catch (SQLException e) { return null; } catch (IllegalArgumentException x) { throw x; ++woofCount; } } }} Simple is hard! public List<Person> getAll() { connection = DriverManager.getConnection("jdbc:oracle:thin:@prod", "admin", "beefhead"); statement = connection.prepareStatement("insert into Dog values (?, ?, ?)"); statement.setLong(1, System.currentTimeMillis()); } if (statement != null) { if (c.next()) { Henrik Kniberg String foundName = c.getString("name"); CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 PhoneNumber phoneNumber = new PhoneNumber(c.getString(“woofCount")); Person person = new Person(foundName, phoneNumber); return person; } else { 13

Velocity calibrationEstimated ActualVelocity Velocity Estimated Actual 40 30 40 30 30 28 40 30 30 31 40 30 30 30Estimated Actual Estimated Actual 40 30 30 40 35 50 30 25 35 30 60 30 20 30 25 Source: Henrik Kniberg CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 14

Technical debt & release planningRemainingstory points 400 We’ll be done by 300 sprint 10! Sorry, we’re late! We should definitely 200 by done by sprint 12! Um... we’re done when we’re done! 100 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Sprint Source: Henrik Kniberg CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 15

3 roles • Product owner • Scrum master Definition of Done • Team Technical debt • .... bla bla .... 3 artifacts • Product backlog • No increased technical debt • Sprint backlog Code duplication • Sprint burndown Test coverage 4 activities • Sprint planning • Daily scrum Code readability • Sprint review • RetrospectiveVmax VmaxVactual Vactual Sustainable pace! velocity velocity time time Source: Henrik Kniberg CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 16

3 roles • Product owner • Scrum master • Team Dealing with technical debt 3 artifacts • Product backlog • Sprint backlog • Sprint burndown 4 activities • Sprint planning • Daily scrum Definition of Done Definition of Done • Sprint review • RetrospectiveVmax • .... bla bla .... • .... bla bla .... • No increased technical debt • Technical debt decreasedVactua l Ro ad to velocity he ll pa ce! a sing Sustainable pace Incre Second step First step (optional) Slow down Slow down even more Stop accumulating debt Start repaying debt time Source: Henrik Kniberg CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 17

Knowledge decays fast Don’t let any bugs escape the Sprint CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010 18

Time cost of&defects for you? Itera&ve Incremental Relative Cost of defects if fixed later504540353025201510 5 010 minutes 1 hour Same Day Next Day 1 Week 2 weeks 1 month 2 months

The bad news does not get better with age!!!We have to go slow to go fast. © Joe Little 2010 20

How do we explain TechnicalDebt to the Product Owner?How do we explain TechnicalDebt to the manager? © Joe Little 2010 21

The importance of a definitionof done.We recommend a detailedDefinition of Done, that is clearabout how we will not buildtechnical debt.

Technical debt & Scrum. Engineering practices Improvements Framework

Key Engineering Practices Which ones??

Key Engineering Practices ...pair programming ...TDD ...continuous integration ...refactoring, refactoring, refactoring ...10 minute build ...automatic unit tests ...automated functional tests (other names) ...automated other testing (regression especially)

How do we give the team theproper incentives?(Or avoid the wrongincentives??)

What do we measure to assureproper incentives?

* We focus on speed and lowwork-in-process.* We see the impedimentsbetter.* We fix the root causes.* Over time, this enableseverything: cheaper, higherquality, faster, more what theywant.

The End Please send me your comments andsuggestions. This is an important topic. Ifit were easy, we as an industry would not have this problem. So, I appreciate your feedback. jhlittle@kittyhawkconsulting.com http://leanagiletraining.com

Technical debt

by LeanAgileTraining / Kitty Hawk Consulting, Inc. on Feb 11, 2011

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Technical debt — Presentation Transcript