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Comparative

Development Methodologies

Lecture 4

Agile Methodologies

For the BSc IS&M Programme

Dell ZhangBirkbeck, University of London

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Agile Methodologies

Reaction against heavyweight methodologies The crushing weight of corporate bureaucracy

The rapid pace of information technology change

The dehumanizingof detailed plan-drivendevelopment

Evolved from the mid 1990s Originally called lightweight methodologies

Sounds not serious/robust enough

Agile Alliance A weekend in February 2001 at Snowbird, Utah.

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Agile Methodologies

eXtreme Programming (XP)

SCRUM

Dynamic Systems Development Method

(DSDM) Feature-Driven Development (FDD)

Adaptive Software Development (ASD)

Crystal Clear Agile Modeling

......

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Agile Principles

Our highest priority is to satisfy the customerthrough early and continuous delivery of valuablesoftware.

Welcome changing requirements, even late indevelopment. Agile processes harness change forthe customer's competitive advantage.

Deliver working software frequently, from a couple ofweeks to a couple of months, with a preference to

the shorter timescale. Agile processes promote sustainable development.

The sponsors, developers, and users should be ableto maintain a constant pace indefinitely.

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Agile Principles

Business people and developers must work togetherdaily throughout the project.

Build projects around motivated individuals. Givethem the environment and support they need, andtrust them to get the job done.

The most efficient and effective method ofconveying information to and within a developmentteam is face-to-face conversation.

Working software is the primary measure of

progress.

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Agile Principles

Continuous attention to technical excellence andgood design enhances agility.

Simplicity the art of maximizing the amount ofwork not done is essential.

The best architectures, requirements, and designsemerge from self-organizing teams.

At regular intervals, the team reflects on how tobecome more effective, then tunes and adjusts its

behavior accordingly.

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Ongoing Debate

Are we returning back to cowboy coding?

Not really.

Agile Methodologies do have disciplines.

Criticism

Hacker Interpretations

e.g.,

responding to change over following a plan Great! Now I have a reason to avoid planning and to

just code up whatever comes next.

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http://agilemanifesto.org/

Would you like tosign it?
http://agilemanifesto.org/http://agilemanifesto.org/

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The Planning Spectrum

B. Boehm. Get Ready for Agile Methods, with Care. IEEE Computer, January 2002.

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Agility

Agility (in a software development sense) The ability to respond quickly to change & environment

The adaptability to suite new or unexpected challenges

Where does agility come from? Agile methodologies derive much of their agility by

relying on the tacit knowledge embodied in the

team, rather than writing the knowledge down in

plans.

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Developers

Agile Methodologies

put a premium on having premium people

critical people factors: amicability, talent, skill and

communication

Plan-Driven Methodologies

invest in life-cycle architectures and plans

use these to facilitate external reviews

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Customers

Agile Methodologies

customers operate in dedicatedmode with the

development team

Plan-Driven Methodologies avoid tacit knowledge shortfalls via documentation

avoid onsite-customer shortfalls via architecture

review boards and independent expert projectreviews

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Requirements

Agile Methodologies

in turbulent, highly-change environments

emergentrather than prespecifiable


determined in advance

including via prototyping

remain relatively stable with change rates with

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Architecture

Agile Methodologies

emphasizes simplicity: maximizing the work not

done

designed for current requirements YAGNI


emphasizes heavyweight architecture and designdocumentation

designed for current and forseeable requirements

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Refactoring

Agile Methodologies

assumes that refactoring is essentially free (with

great developers and small systems)

Plan-Driven Methodologies assumes that refactoring effort increases with the

number of requirements (with less-than-great

developers or very large systems)

the 20% problems (causing 80% rework) come

largely from architecture-breakers

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Size

Agile Methodologies

need tightly coordinated teamwork

e.g., face-to-face communication

are suitable for small teams (< 15 or 20 people)


scale better to larger (million-line) projects

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Primary Objective

Agile Methodologies

rapid value

early and continuous delivery


high-assurance

predictability, repeatability, and optimization

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Risk Management

How much planning is enough?

Risk Exposure

RE = P(L) x S(L)

Probability of Loss P(L)

Size of Loss S(L)

REQuality + RESpeed RE

Quality

is caused by inadequate plans

RESpeed is caused by delays (market share erosion)


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Agile Methodologies - Exercise

What are the aspects of software

development that all agile methodologies

share?

(A) User involvement is vital to success.

(B) Build and release software in small increments.

(C) Attention to quality and excellence.

(D) Conformance to standards.

Teach Yourself Extreme Programming In 24 Hours.

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Video

Are You Agile or Are You Fragile?

by Scott Ambler

http://video.google.com/videosearch?q=+Are+You

+Agile+or+Are+You+Fragile
http://video.google.com/videosearch?q=+Are+You+Agile+or+Are+You+Fragilehttp://video.google.com/videosearch?q=+Are+You+Agile+or+Are+You+Fragilehttp://video.google.com/videosearch?q=+Are+You+Agile+or+Are+You+Fragilehttp://video.google.com/videosearch?q=+Are+You+Agile+or+Are+You+Fragile

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Take Home Messages

Agile Manifesto

Agile vs. Plan-Driven

The Planning Spectrum

Home Ground

Comparative Risk Exposure Profiles

Documents

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