Agile Software Development

K.Ingram 1 Sept 2007

Agile Software Development


Contents

Agile Software Development:1. What is it?

2. Agile’s Values, Principles, Practices

3. The Spiral Life Cycle

4. Agile Methodologies

5. Managing an Agile Project


What is Agile Development?

• A concept of lightweight process i.e. avoiding unnecessary overheads

• Aims to avoid some of the pitfalls in software development whilst achieving good results

• It is a further step forward from Rapid Applications Development (RAD)


Rapid Applications Development

• NOT a methodology – an approach that includes user-centred design

• DSDM is one methodology

• recognises the 80:20 rule (Pareto’s Law)• Phases of RAD:

– Requirements planning– User design– Construction– Cutover


The phases of RADUser design

JAD workshop

PrototypingCASE

Requirements planning

JRP workshop

Cutover

Construction

PrototypingCASE

KEY

Phases

Techniques

Tools


RAD: pros and cons

• avoids specification

becoming out of date before implementation

• Allows speedy implementation of at least some parts of system

• helps meet user’s requirements

• Needs good staff –

highly skilled and highly focused and able to work under pressure

• Needs a range of good software development tools

• Difficult for loosely-scoped projects


Agile: In General terms…

• As guidance, it has sets of – Values– Principles – Practices

• Recognises the 80:20 rule (Pareto’s Law)


The Agile Values

“While there is value in the items on the right, we value the items on the left more.

• Individuals and interactions over processes and tools

• Working software over comprehensive documentation

• Customer collaboration over contract negotiation• Responding to change over following a plan”[http://agilemanifesto.org/]

See also: http://www.ambysoft.com/essays/agileManifesto.html


The Agile Principles

• See http://agilemanifesto.org/principles.html

• They include– Deliver working software frequently… – Welcome changing requirements…– Business people and developers must work

together daily…– …..

http://agilemanifesto.org/principles.html


The Agile Practices for Modeling(1)

• A range of stakeholders to be actively involved in decision-making and prioritizing

• Use the appropriate artifact(s) (i.e. technique(s))• Anyone can work on any part of any model• As the model is created, consider how each aspect

can be tested• Create different models (e.g. requirements, essential

use case, etc) in parallel to get different perspectives• Work on another artifact when you get stuck with 1• Keep contents of models as simple as possible

(whilst being extensible)


The Agile Practices for Modeling(2)

• Keep the models clutter-free • Make models available for others to see• Model in small rather than large increments • Model as a team where there is a core set of

models needed for understanding• Prove the model will work by coding it and

testing it – use iterations• Use the simplest tools depending on the

purpose of the artifact e.g. whiteboards, post-it notes as well as software modeling tools

Agile Model Driven Develpment


[www.agilemodeling.com]


Some Agile Methodologies(in no particular order)

1. SCRUM

2. DSDM

3. eXtreme Programming


SCRUM

www.controlchoas.com/APMG_files/slide0202.htm [8/8/02]


eXtreme Programming

• Based on the Values of – simplicity, – communication, – feedback, – courage,– humility.

See also: http://www.extremeprogramming.org/index.html


DSDM

Tested prototype

Tested product

User functionality

Non- functional requirements


DSDM

• Project management• Estimating• Timeboxing• Configuration

management• Testing• Quality Assurance

• Roles and Responsibilities

• Team structure• Tool environments• Risk management• Building for

maintainability

DSDM covers all parts that standard methodologies cover:


Managing an Agile Project

1. Present a vision

2. Nurture resources to do the ‘best possible’

3. Remove obstacles

4. Let the team get on with it

• New techniques (e.g. burn-down charts) may be used


Agile Project Plan

• Vision: what the business operation will look like• Identify business, functional and technical

architecture• Who will do the development?• Identify product releases, milestones and

‘sprints’• Return on Investment: what benefits will there

be and how will they be assessed


Summary• Agile development uses a lightweight, iterative

approach• Agile’s Values, Principles, Practices support the

concept of ensuring skilled and motivated staff have the information, the tools and the space to get on with it

• It is based on The Spiral Life Cycle• Agile Methodologies include SCRUM, DSDM and XP• Managing an Agile Project still requires identification

of milestones and releases, monitoring of progress and quality, but a new approach is required.


Agile References

• http://agilemanifesto.org/• http://www.agilealliance.org/• http://www.agilealliance.org/library list of categories of

articles **• http://www.methodsandtools.com/mt/download.php?

summer07• http://www.methodsandtools.com/PDF/mt200702.pdf

esp the 2nd paper ‘What’s wrong with Agile methods: Some principles and values to encourage quantification’

• http://www.controlchaos.com/about about SCRUM **• www.extremeprogramming.org

Agile Software Development

Documents

Transcript of Agile Software Development