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Agile Software Development

Chris Platner

27-Jan-2010

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Who am I?

› 14 years at Serena, a maker of Application Lifecycle Management Tools

› Worked with 2 co-inventors of Scrum

› Principal at Critical Span, a software consulting firm

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Outline

› Do I really need process?

› Common Processes Overview

› Agile Scrum– Activities– Roles– Best Practices

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Who cares about Process?

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if (you_write_software) {

you_have_a_software_process = true;}

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The Main Goal

› The main goal should always be to deliver quality, tested software that satisfies the customer, and do it in a sustainable manner

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Okay, What Processes Are There?

› Chaotic– None*

› Planned– Waterfall

› Iterative– Agile

› and many more…– Capability Maturity Model – Integrated (CMMI)– Extreme Programming (XP)– Crystal– RUP– Spiral– etc.

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We Don’t Need No Stinkin’ Process

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We Don’t Need No Stinkin’ Process

› Q: Let’s just Code Like %$#&*!!

› A: Yes, but…– Bug fixing is almost always postponed until the end– Software is often very late, low quality, or both– Delivered software is often difficult to maintain– Requires lots of ‘commitment’, and is not sustainable

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Waterfall

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Requirements

Design

Coding

Integration

Testing

Installation

Operation/Maintenance

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Waterfall

› Q: Let’s figure out everything before we start coding!

› A: Not Likely…– Users’ requirements change over time – “That’s just what

I asked for, but not what I want”– Strict waterfall doesn’t allow feedback after passing to

next phase. Learning in later phases can’t easily be passed back to earlier ones.

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Agile

– An iterative process– Short iterations– Emphasis on interaction with a customer– Practices

• TDD• Pair Programming• Continuous Integration

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Agile

› Manifesto for Agile Software Development– We are uncovering better ways of developing software by

doing it and helping others do it.  Through this work we have come to value:

• Individuals and interactions over processes and tools• Working software over comprehensive documentation• Customer collaboration over contract negotiation• Responding to change over following a plan

– That is, while there is value in the items on the right, we value the items on the left more. 

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from http://agilemanifesto.org/

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Agile Scrum

› Scrum is one way of realizing Agile– Daily Scrum meetings– 2-4 week iterations called sprints– Relies heavily on smart, flexible people– Self-organizing teams– Sustainable– Always have a shippable product

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Who uses Scrum?

› Independent Software Vendors (ISVs)

› Fortune 100 companies

› Small startups

› Internal development

› Contract development

› Companies using Scrum– Adobe, Amdocs, F5 Networks, General Electric, HP, Intel,

Intuit, LexisNexis, Microsoft, Motorola, Oracle, Serena, Siemens, Sun Microsystems

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What has Scrum been used for?

› FDA-approved, life-critical software for x-rays and MRIs

› Enterprise workflow systems

› Financial payment applications

› Biotech

› Call center systems

› Tunable laser subsystems for fiber optic networks

› Application development environments

› 24x7 with 99.99999% uptime requirements

› Multi-terabyte database applications

› Media-neutral magazine products

› Web news products

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Where Did Scrum Come From?

› Jeff Sutherland, John Scumniotales, and Jeff McKenna– Initial Scrums at Easel Corp in

1993

› Ken Schwaber– ADM

› Initial definitions of Scrum at OOPSLA 96 with Sutherland

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Agile Scrum Overview

› Roles

› Activities/Rhythms

› Artifacts

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Agile Scrum Overview

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Primary Roles

› The Team– Does the work of designing, implementing, testing

› Scrum Master– Runs the Scrum meetings

› Product Owner– Represents the customer

› Pigs– The Team, Scrum Master

› Chickens– Product Owner, Customers, Managers

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Chickens and Pigs

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The Team, Illustrated

› Short video on teamwork from the IT Crowd: http://www.youtube.com/watch?v=pGFGD5pj03M

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The Team

› Typically 5-10 people

› Cross-functional– Programmers, QA, UI Designers, etc.

› Teams are self-organizing– Primary focus is to meet sprint goals

› Membership can change only between sprints

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The Scrum Master

› Represents management to the project

› Typically filled by a Project Manager or Team Leader

› Responsible for enacting Scrum values and practices

› Main job is to remove impediments

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The Product Owner

› Represents the customer

› Makes sure the ‘Right Things’ are in the backlog

› Writes and prioritizes User Stories

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Activities

› Story Time*

› Sprint Planning

› Sprinting

› Daily Scrum Meeting– 3 questions

› Sprint Review– Quick demo of work completed

› Sprint Retrospective– Continuous Improvement

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Story Time

› The Team reviews User Stories with the Product Owner

› Initial estimates of story size

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Sprint Planning

› Select User Stories or items to be worked on for the next sprint– Often, the Sprint will have a Theme

› Highest priority items are taken from the Product Backlog and placed on the Sprint Backlog

› The Team votes on how long each item will take– Planning Poker– Can use either User Stories or Tasks

› Planning is over when The Team is satisfied with the results

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Sprint

› Analogous to ‘iterations’

› 2-4 weeks

› Designing, coding, and testing occur during the sprint

› No changes can occur in a sprint

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Daily Scrum

› Part of the daily rhythm

› Always starts on time, and lasts only 15 minutes (should be less)

› Only pigs can talk

› 3 questions– What did you work on yesterday– What will you work on today– Any blocking issues*

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Sprint Review

› Demo all the completed User Stories– Only complete, ‘approved’ stories are demonstrated

› Minimal preparation (and no faking)

› Participants– The Team– Customers– Management– Product Owner– Other engineers

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Sprint Retrospective

› Review the last sprint

› What went well?

› What could be improved?

› Choose the improvements to make in the next sprint

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Artifacts

› Product Backlog

› Sprint Backlog

› Burndown Chart

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Product Backlog

› A list of User Stories to be delivered– May also contain Epics– Stories may be organized into themes

› Usually a combination of – User Stories (‘As a…’)– Can also contain tasks

› List is prioritized by the Product Owner– Typically a Product Manager, Marketing, Internal

Customer, etc.

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Product Backlog

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Sprint Backlog

› A list of Tasks or User Stories that The Team has agreed to complete

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Sprint Backlog

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Burndown Chart

› Shows progress during the sprint

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Progress

752 762

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200

100

200

300

400

500

600

700

800

900

Date

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Other Important Things

› User Story

› Planning Poker

› The meaning of Done

› TDD

› Continuous Integration

› Velocity

› Spike

› Theme

› Epic

› Scalability

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User Story

› A User Story is a requirement that is written in customer’s language

› Typical format is ‘As a [user/role], I want [goal/function], so that [reason]’

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Planning Poker

› Quick way to estimate relative task size– Sizes are chosen from Fibonacci numbers (i.e. 1, 2, 3, 5,

8, 13, etc.)

› Each Task or User Story is estimated by the team

› The Team must reach consensus on the relative sizes

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The Meaning of Done

› Defining ‘done’ is critical:– Coded– Tested (unit and functional)– Reviewed– (possibly) Documented

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TDD

› Test Driven Development– Writing Tests will improve the design and stability of the

code– Only writing enough code to make a test pass reduces

waste

› Process– Write a test – Run the (failing) test– Write some code– Run the (passing) test

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TDD

› Use frameworks and mock objects

› Kinds of tests– Unit– Integration– Functional

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Continuous Integration

› A set of practices around software builds– Commit often– Build and test each commit

› Tools:– Hudson– CruiseControl

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Velocity

› The amount of work that a Team can handle in one sprint.

› Estimated from past performance

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Spike

› A time-boxed period of research and development

› May be used for proof of concept

› No deliverable for a product

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Theme

› A group of User Stories for related functionality

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Epic

› A large User Story, especially one that is a lower priority, and has not been broken into more detailed, smaller User Stories

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Scalability

› Typical Scrum team is 5-10 people

› Sutherland used Scrum in groups of 600+

› Cohn used in groups 100+

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Where to go next?

› Agile Scrum– http://www.mountaingoatsoftware.com/scrum– http://www.controlchaos.com– Agile Software Development with Scrum (Ken Schwaber

and Mike Beedle)– Agile Project Management with Scrum (Ken Schwaber

and Mike Beedle)

› Agile in General– http://www.agilealliance.com

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Other References

› Ruminations on C++, Andrew Koenig, Barbara Moo, 1997– Excellent discussion of why small projects are often successful,

while larger ones are not. Read all of chapter 2.

› Agile Software Development, Alistair Cockburn, 2002– Great introduction to agile development.

› Software Project Survival Guide, Steve McConnell, 1998– If you want to be a manager, or understand managers, Steve’s

books are must-have’s.

› Rapid Development – Taming Wild Software Schedules, Steve McConnell, 1996

› Martin Fowler’s Writings – Many interesting articles on agile methodologies. See http://www.martinfowler.com, http://thoughtworks.com/library/newMethodology.pdf

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Thank You!

› Q&A

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