Agile Software Development

T-110.6130 Systems Engineering in Data Communications Software P

29.9.2011

Kristian Rautiainen, Aalto University

Agenda

• Agile Software Development Basics

• eXtreme Programming (XP)

• Scrum

• 10 Ways to Fail when Going Agile

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Agile Software Development Basics

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Agile software development

• Structured and disciplined, fast-paced Iterative and Incremental Development (IID)

– NOT “build-and-fix” or “hack away”

• Packages existing good software engineering practices

– Nothing new, except the underlying philosophy and the combination of practices

• Embraces change rather than controls it

– Suitable for extremely turbulent environments

• Focuses on delivering business value in frequent increments

– Customer/User involvement paramount

• Can’t be used in all projects!

– E.g. small teams recommended

• More information:

– http://www.agilealliance.org/

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Agile Manifesto

• Signed by authors of ASD, XP, Scrum, Crystal, FDD, DSDM, and ”pragmatic programming” + some others in Feb 2001

• Agree at the first level – need to respond to change

• Agree at the second level (Agile Manifesto) – individuals and interactions over processes and tools – working software over comprehensive documentation – customer collaboration over contract negotiation – responding to change over following a plan

• Agree at the third level – 12 more detailed statements (Principles)

• Don’t agree at the fourth level – detailed project tactics

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6

Principles of the Agile Alliance

• Satisfy the customer through early and continuous delivery of valuable software

• Agile processes harness change for the customer’s competitive advantage

• Deliver working software frequently

• Working software is the primary measure of progress

• Agile processes promote sustainable development at a constant pace

• Business people and developers must work together daily

• Build projects around motivated individuals, give them support and trust them to get the job done

• The most efficient and effective way of

conveying information is face-to-face

conversation

• Attention to technical excellence and

good design enhances agility

• Simplicity--the art of maximizing the

amount of work NOT done--is essential

• The best architectures, requirements,

and designs emerge from self-

organizing teams

• At regular intervals the team tunes and

adjusts its behavior to become more

effective

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Agile process models

• Provide the “project tactics” – A set of specific values, principles, and practices

• Many models have been proposed

– eXtreme Programming (XP) – Adaptive Software Development (ASD) – Rapid Application Development (RAD) – Dynamic Solution Delivery Model (DSDM) – Scrum – Crystal – Feature-Driven Development (FDD) – Lean Development (LD) – ...

• Most agile process models employ time pacing

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The concept of time pacing

• Time pacing refers to – Creating a rhythm for product development by timeboxing

development work

• The schedule is fixed

• The scope is flexible (prioritization needed)

• Time pacing can be done on several time horizons – Time horizon = planning time horizon, i.e. the length of the timebox

– Long-term goals are split into short-term sub goals

– This provides

• visible progress on shorter time horizons by reaching the sub goals

• flexibility to reflect on and change plans and goals in the control points based on visible and concrete progress

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Agile philosophy and time horizons

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Product Backlog

Release Backlog

Iteration

Backlog

Release Backlog

planned scope for release allocated into

Iteration

Backlog

Iteration

Backlog

parts chosen and allocated into

consists of tasks that are needed to

implement the allocated backlog items

Every idea, feature, bug, etc.

considered for the product is kept in

Go

vern

ance

Pro

gre

ss s

tatu

s

Progress status of the tasks of an Iteration checked in Daily Heartbeat meetings

Progress of a Release checked in Iteration Demo

Roles: 1 Product Owner

1 Team 1 Coach

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Sweet spots of agile software

development • 3-8 people in one room

– Information moves the fastest face-to-face

• Onsite expert user – Minimized time for feedback of the solution

– Possibility to ask questions immediately fastest response time

• One-month (max) iterations – Feedback of the product and the process

– Today’s “industry standard” is 2-week iterations

• Supporting infrastructure/technology in place – Continuous Integration environment with automatic build process

– Fully automated regression tests • Confidence to changing and improving the system

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Comparing process models

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Specification

Design

Implementation

Test

Sequential Iterative &

Incremental (IID)

eXtreme

Programming (XP)

Tim

e

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eXtreme Programming (XP)

(Based on the original book by Kent

Beck)

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XP Values (1/2)

• Communication

– Lack of it is the reason for most

problems

– Punishment from bad news kills it

– XP employs practices that keep

programmers, customers and

managers communicating

• Simplicity

– What is the simplest thing that

could possibly work?

– General vs. simple design

• anticipatory design assumes

more work today saves work

later

– YAGNI

• low rate of changes

– anticipatory design

• high rate of changes

– refactoring and

continuous design

– A simple solution is easier to

understand

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XP Values (2/2)

• Feedback

– Concrete feedback about the state

of the system

– Scale of minutes or days

• unit tests, quality of stories

(requirements), progress of

tasks

– Scale of weeks or months

• acceptance tests, schedule,

system in production

• Courage

– Changing the system

– Throwing code away

– Pair programming

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XP Principles

• Fundamental principles

– rapid feedback

• critical for learning

– assume simplicity

• treat every problem as if it can be solved with simplicity

– incremental change

• series of smallest changes that make a difference

– embracing change

• best strategy preserves most options while actually solving your most pressing problem

– quality work

• excellent quality

• nobody likes doing a bad job

• Secondary principles

– teach learning

– small initial investment

– play to win

– concrete experiments

– open, honest communication

– work with people’s instincts, not

against them

– accepted responsibility

– local adaptation

– travel light

– honest measurement

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XP Practices

• Practices

– planning game

– small releases

– test driven development

– continuous integration

– system metaphor

– simple design

– refactoring

– pair programming

– collective code ownership

– coding standard

– whole team (on-site customer)

– sustainable pace

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XP Process

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Scrum

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Scrum Process Overview

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Scrum roles – Product Owner (PO)

• Represents the interests of everyone with a stake in the project/product

• Creates the project’s ROI objectives and release plans

• Manages and controls the Product Backlog (PBL)

– Ensures that the PBL is visible to everyone

– Sets priorities for the items in the PBL

– For PO to succeed, everyone must respect his/her decisions

– Works with others to estimate items in backlog (for total effort)

– Participates in Sprint Planning Meeting (and Sprint Review)

– Participates in re-scoping or re-prioritizing the sprint

• PBL

– PBL is an evolving, prioritized queue of business and technical functionality that needs to be developed into a system

– PBL emerges from many sources

• Marketing, Sales, R&D, Support, ...

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Scrum roles – Scrum Master

• Agile coach

– Master of the Scrum process and practices

– Coaches the team members

• Facilitator/impediment remover

– Shields the team from outside interruptions

– Helps remove impediments

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Scrum roles – Development team

• Responsible for realizing the PO’s vision for the product

– The team makes the technical choices and delivers working

software to demo at the end of Sprints

• Shared responsibility

• Self-organized and empowered

– The team chooses its ways of working

– No appointed team leaders, leaders emerge for different

situations

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10 Ways to Fail when going Agile

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Ceremony Without Understanding

• Doing everything as before, but calling it Agile

– New terminology, but same routines

– E.g. Weekly meeting => weekly Scrum...

• ...or Daily Scrum that lasts as long as a weekly meeting

• Fallacy of allowing feature creep during iterations

– ”because we’re supposed to be agile”

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Underestimating Transition Effort and

Time

• Organisational change or process improvement is

always challenging and takes a lot of time

– ”This agile thing doesn’t work for us. We tried it for a couple of

months, but...”

– Fallacy of not risking some time now in order to win a lot of time

in the future

• Transition to Agile slows down productive work for an unknown

period of time

– Business representatives tend to be impatient...

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Throwing Away Existing Good Practices

• ”Let’s start from scratch with this Agile thing”

• ”We used to observe users to elicit requirements. Now

we invite them to iteration demos instead”

• ”Something that works for us is not considered Agile. We

have to throw it away.”

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Cultural Conflicts

• Project manager => Scrum Master

– You often see this role transition in companies

• But the differences in the roles cause trouble and confusion

• (technical) project manager => (technical) product owner is actually

an easier transformation

• Breaking down ”silos”

– Creating truly cross-functional teams is a big challenge...

• ...but without them lots of effort for coordination is needed

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Challenging Roles

• Product Owner

– Need I say more...?

• Empowered, self-organised team

– ”Say what?”

– A transition from a ”clear roles and responsibilities + a project

manager to tell us what to do” to self-organised is rocket science

and a huge step for most people

• A lot of coaching and support is needed for the role

transitions (also for top-level managers!)

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Lacking Competence

• Getting rid of the difficult practices because they take

too much time to learn

– ”Test-Driven Development (TDD) was really hard to understand

and learn, so we stopped doing it”

– You need to understand the trade-offs and underlying

assumptions, otherwise you end up in total ad-hocracy

• Working at high velocity requires high discipline and

skills + good-quality software

– Work on building competence to the people, it will always pay off

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Minimal Plans = Minimal Planning

• Fallacy of planning only in Release or Iteration planning

sessions

– ”I just saw the demo. Now I need time to figure out what you

should do next”

– Planning should be made ”continuously” in a rolling wave

fashion

• Requirements refinement (Agile Product Management)*

• 5% workshops (aka story time) have not been around in most

companies (not for long, anyhow)

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*K. Vlaanderen, S. Jansen, and S. Brinkkemper, “The agile

requirements refinery: applying scrum principles to software

product management,” in Proc. 3rd International Workshop

on Software Product Management, 2009.

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Emerging architecture =

no upfront architectural work • Working in short iterations may compromise the

architecture – ”The best architectures emerge”

• Sure thing, as long as you have the best people

– ”Just enough arcitecture”

• How do you know how much is enough?

– ”We have these 10 teams working on the release of this product”

• ”Architectural runway” is a must

• Architectural work is challenging no matter what you call the development process!

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Anyone Seen the Onsite Expert User?

• Working with a simple backlog may cause losing sight of

the ”Big Picture”

– Most backlogs only contain vague one-liners, not even proper

user stories

– If the onsite expert is not there to explain things, the end result

might be completely off target

• The positive thing is that we know it pretty fast, but it is still waste

– How much explanations should be written?

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Agile Only Concerns R&D

• After all, the Product Owner is part of the team and is responsible for all ”that other stuff” – Still, agile (and lean especially) does change the way everybody

should be thinking about developing software

• Agile requirements (= backlogs, stories, ...) mean that Business representatives need to work in new ways too!

• Customers still want detailed plans and contracts! – Business/sales representatives force the teams to produce

detailed plans upfront

– Who trains the customers?

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Questions or comments?

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