Agility and Quality

Agility and QualitySebastian Bergmann May 21 st 2011

Hello! My name is Sebastian. Sebasti an

Hello! My name is Sebastian …and this is what I do: sebastian@thePHP.cc Co-Founder of The PHP Consulting Company sebastian@phpunit.de Creator and Main Developer of PHPUnit sebastian@php.net Contributor to PHP sebastian@apache.org Contributor to Zeta Components sbergmann@{acm.org | ieee.org} Practitioner of academic computing

Why do we want to be agile?We need to be able to change the application  as fast as needed to meet business requirements  and in such a way that the cost of the change does not exceed the business value of the change

The ”Time, Money, Quality – Pick two” Fallacyhttp://www.startuplessonslearned.com/2008/10/engineering-managers-lament.html

Tradable Quality Hypothesishttp://martinfowler.com/bliki/TradableQualityHypothesis.html By ”saving” on internal quality we do not gain in the other dimensions of cost, scope, or speed. Internal quality is an enabler of speed. Reducing internal quality slows us down.

Agile EnvironmentsScrum is an agile method for project management. http://en.wikipedia.org/wiki/File:Scrum_process.svg

Agile EnvironmentsScrum is not an agile method for software engineering. http://en.wikipedia.org/wiki/File:Scrum_process.svg

Agile EnvironmentsCommon elements of agile software development Coding  Collective Code Ownership  Test-Driven Development  Continuous Integration & Continuous Inspection Testing  All code must have unit tests  All code must pass all unit tests before release  When a bug is found, tests are created Operations  Continuous Deployment & Continuous Delivery

Agile development puts a focus on software quality.

Software QualityExternal Quality Internal Quality Functionality  Working code that is Usability  unique (not duplicated) Reliability  simple (not complicated) Performance  clear (not puzzling) Supportability  easy to adapt and extend This slide contains material by Jeff Langr and Tim Ottinger

Test-Driven DevelopmentDisciplined software development practicethat focuses on software designby first writing automated unit testsfollowed by production codein short, frequent iterations This slide contains material by David S. Janzen

Test-Driven Development Fewer defects Fewer statements Lower computational complexity Lower coupling between classes Higher test coverage and volume This slide contains material by David S. Janzen

Unit TestsTest a unit of code isolated from its dependencies.

Static Code Analysis

Quality Assurance Tools for PHPOverview http://phpqatools.org/

Feel the pulse of your project!

Continuous Integration of PHP Projects Jenkins http://jenkins-ci.org/ Template for Jenkins Jobs for PHP Projects http://jenkins-php.org/ PHP Project Wizard (PPW)  https://github.com/sebastianbergmann/php-project-wizard

Continuous Integration of PHP ProjectsAlternative Continuous Integration Servers CruiseControl phpUnderControl Arbit Atlassian Bamboo JetBrains TeamCity

Avoid ”Big Bang” Deployments

Deploy Early, Deploy Often”Software delivers no revenue until it is in the hands of its users. […] For large companies every week of delay between having an idea and releasing the code that implements it can represent millions of dollars in opportunity costs […]” – Jez Humble and David Farley

Deploy Early, Deploy Often”Software delivers no revenue until it is in the hands of its users. […] For large companies every week of delay between having an idea and releasing the code that implements it can represent millions of dollars in opportunity costs […]” – Jez Humble and David Farley”Our highest priority is to satisfy the customer through early and continuous delivery of valuable software.” – Agile Manifesto

Deploy Early, Deploy Often”Flickr was last deployed 6 hours ago, including 5 changes by 3 people.In the last week there were 74 deploys of 447 changes by 22 people.” – http://code.flickr.com/

Deploy Early, Deploy Often”Flickr was last deployed 6 hours ago, including 5 changes by 3 people.In the last week there were 74 deploys of 447 changes by 22 people.” – http://code.flickr.com/”Every engineer at Etsy writes automated tests on a daily basis, and our Hudson continuous integration server runs about 2500 tests with every code push. Since we push code around 20 times a day, that means running around 250,000 PHPUnit tests in a typical work week!” – http://codeascraft.etsy.com/

Latent Code PatternsFeature Flags (or Feature Bits, Feature Flippers, Buckets, …)

Latent Code PatternsFeature Flags (or Feature Bits, Feature Flippers, Buckets, …)<?php// …if ($cfg->enable_unicorn_polo) { // do something new and amazing here.}else { // do the current boring stuff.}// … http://code.flickr.com/blog/2009/12/02/flipping-out/

Latent Code PatternsFeature Flags (or Feature Bits, Feature Flippers, Buckets, …)Further reading  http://code.flickr.com/blog/2009/12/02/flipping-out/  http://github.com/blog/677-how-we-deploy-new-features  http://blog.forrst.com/post/782356699/how-we-deploy-new-features-on-forrst  http://www.infoq.com/presentations/Feature-Bits

Latent Code PatternsDark Launching

Latent Code PatternsThe Nuclear Option

Latent Code PatternsDark Launching and The Nuclear OptionFurther reading http://www.facebook.com/note.php?note_id=96390263919

DevOps http://en.wikipedia.org/wiki/File:Devops.png

Software Quality in PHP Projects Sebastian Bergmann Stefan Priebsch Wrox, May 2011

The End Web: http://thePHP.cc/ http://sebastian-bergmann.de/ Mail: sebastian@thePHP.cc Twitter: @s_bergmann Slides: http://talks.thePHP.cc/

Agility and Quality

by Sebastian Bergmann on May 21, 2011

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Agility and Quality — Presentation Transcript