QCon Beijing - April 2010

TECHNICAL DEBT ... And What to Do About It!

THE SPEAKER Kane Mar, Scrumology.com OutSofting.com Scrum Training Scrum Coaching Scrumology.com

DO YOU KNOW THESE PROBLEMS? Your team cannot change the system quick enough to meet changing business needs Your code is so complex only a few people in the company are allowed to make changes Your spend more time ﬁxing defects introduced by new functionality You have recently re-platformed to newer technology Scrumology.com

WHY SHOULD YOU CARE? Be able to meet changing business needs Reduce Total Cost of Ownership Build higher quality products Keep customers happy Scrumology.com

WHAT IS TECHNICAL DEBT The concept of software complexity as debt was originally coined by Ward Cunningham in an experience report for OOPSLA ‘92 (*) Reference: http://c2.com/doc/oopsla92.html Scrumology.com

WHAT IS TECHNICAL DEBT? A big pile of deferred work can gum up a project, yet many of the items on the list don't appear on a project team's radar, especially if the focus is primarily on new product features. Yet removing accumulated sludge needs to be accounted for in planning! Therefore: Make the debt visible. Keep an explicit list Technical Debt Scrumology.com

HOW DOES TECHNICAL DEBT HAPPEN? By not enforcing high quality standards Cutting corners to achieve a higher velocity to meet timelines As the velocity of system goes down, even more corners are cut Scrumology.com

COST OF MAINTENANCE Product Burndown 100 90 80 Product Backlog 70 60 50 40 30 20 10 0 0 1 2 3 4 5 6 7 8 9 Iteration Scrumology.com

COST OF MAINTENANCE Cost of Maintenance Maintenance Cost 0 1 2 3 4 5 6 7 8 9 Release Scrumology.com

SIGNS OF TECHNICAL DEBT The code is considered part of a core or legacy system There is either no testing, or minimal testing surrounding the code ... the legacy system is not in a know state There is highly compartmentalized knowledge regarding the core/legacy system, and it may be supported by only one or two people in the company (over specialization) Scrumology.com

SIGNS OF TECHNICAL DEBT It takes as long to ﬁx defects caused be adding new functionality, as it does to add the new functionality Re-platforming ... and then repeat the mistakes of the past Scrumology.com

AVOID TECHNICAL DEBT Development teams must curb over-optimism in assessing availability and capacity Management redirects attention from applying pressure to removing organizational impediments to progress Product Owners understand the iron triangle, ownership of risks, and impact of cutting quality ScrumMaster must prevent demonstration of any work that is not “done” Scrumology.com

AVOID TECHNICAL DEBT Implement the Agile Technical practices: Continuous Integration Test Driven Development Refactoring Pair Programming Scrumology.com

STRATEGIES FOR PAYING TECHNICAL DEBT Two strategies to consider: Highest interest rate ﬁrst approach Lowest balance ﬁrst approach Scrumology.com

PAYING OFF TECHNICAL DEBT Described by Michael Feathers in “Working Effectively with Legacy code” Start by introducing Continuous Integration Write Automated Tests around customer reported defects Over a period of time a testing framework will be built up around the most brittle code Scrumology.com

AND AVOID THIS ANTI- PATTERN There is a temptation to try and write a comprehensive testing framework around the entire product, but: This does not address the defects that the customer views as most important You may run out of money before you complete the framework, and You are not delivering new business value Scrumology.com

IN CLOSING ... By focusing on reducing technical debt, we can: Better meet changing business needs reduce Total Cost of Ownership Build higher quality products Keep our customers happy Scrumology.com

THANK YOU!

REFERENCES http://www.infoq.com/presentations/agile-quality-canary- coalmine http://martinfowler.com/articles/continuousIntegration.html “Working Effectively with Legacy code,” by Michael Feathers “Test Driven Development: By Example”, by Kent Beck Scrumology.com

PHOTOS CREDITS http://www.flicker.com/photos/yujin_it http://www.flickr.com/photos/majamom/ http://www.flickr.com/photos/slayer23/ http://www.flickr.com/photos/44442915@N00/ http://www.flickr.com/photos/eivindw/ http://www.flickr.com/photos/library_of_congress/ http://www.flickr.com/photos/walkn/ http://www.flickr.com/photos/29143375@N05/ http://www.flicker.com/photos/vernhart/ Scrumology.com

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QCon Beijing - April 2010

by Kane Mar

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