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1 Evolutionary Development T. Gilb. The Agile Alliance A group of writers, developers and consultants, mostly from the OO (object- oriented community)

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Presentation on theme: "1 Evolutionary Development T. Gilb. The Agile Alliance A group of writers, developers and consultants, mostly from the OO (object- oriented community)"— Presentation transcript:

1 1 Evolutionary Development T. Gilb

2 The Agile Alliance A group of writers, developers and consultants, mostly from the OO (object- oriented community) Martin Fowler – ex data analyst with the NHS – ‘UML Distilled’, ‘Analysis Patterns’ Ken Beck and Ward Cunningham – Smalltalk gurus – CRC cards Steven Mellor – Real time systems

3 Agile manifesto - Values Individuals and interactions –Over processes and tools Working Software –Over comprehensive documentation Customer collaboration –Over contract negotiation Responding to change –Over following a plan

4 Keyword- ‘Developer’ No analyst / programmer distinction Distinction is caused by the waterfall model Distinction causes need for documents which have no long-term value and limit change Distinction not viable in the long-term – analysts get out of touch with rapidly- changing technology

5 5 The Generic Agile Life cycle

6 6 XP Pitched as: Addressing “the specific needs of software development conducted by small teams in the face of vague or changing requirements” Key Name: Kent Beck. Where invented: USA Year first used: Pre-2000 First used on: C3 project Chrysler; 8 developers. Now used on: All over the place by different groups/people.

7 7 Small Cross-Functional Teams ConceptXPScrumCrystal OrangeDSDM Number of teams1 team per project1 – 4 or moreVariable; up to 40 people so probably 1 – 10 or so. 1 – 6 Team size3 – 165 – 94 – 82 – 6 Team Members / Roles Customer, Programmer, Tester, Tracker, Coach Scrum master, Experienced Engineer, Junior Engineer, [QA Tester], [Writer] Business Analyst- Designer, Designer- Programmer, UI Designer, [Tester ] Team Leader, Ambassador User, [Advisor User], Senior Developer, Developer, Scribe Project RolesBig BossProject Manager/ Scrum master, Product Owner Sponsor, Project Manager, Architect, Technical Facilitator, Design Mentor Visionary, Executive Sponsor, Project Manager, Technical Co-ordinator, Facilitator

8 Extreme Programming (XP) Best known example of an agile method Developed by Kent Beck and others (Fowler, Jefferies) using internet discussion board – a wiki A disciplined method despite the ‘anarchist’ tag Customer requirements focus Role specialisations – release manager, coach … as required

9 XP Values Simplicity Communication Feedback Courage

10 12 elements Small releases The planning game Continuous integration Test-driven Development Sustainable Pace Whole team Metaphor Pair programming Design improvement Simple Design Collective Code Ownership Coding standards

11 Small releases Agile and XP methods are refinements of iterative methods Plan to release a functional system to the users about every month Release an iteration to the customer for customer tests every week Integrate to get a working system several times a day!

12 The Planning game Accurate prediction at the start of a project is too difficult So STEER the project, little by little Start with a collection of ‘user stories’, tasks or units of functionality – developers estimate, together allocate to a release Make plan visible – task cards on a wall

13 Continuous integration Integration of multiple software components, hardware, networks is a very troublesome phase So do it frequently –Only small problems appear and can be fixed –There is always a working system to test, use and as a common code base

14 Test Driven development Write the tests for a function first. Then write the code to meet those tests – and no more! Don’t anticipate future requirements (see Simple Design) Automate the testing, so that the tests can be rerun frequently Developers write the tests Customer also writes tests for a release

15 Sustainable Pace (40hr week) Developers forced to work long overtime hours to meet unrealistic deadlines make more mistakes, and can actually cost time rather than save it So work hard, but keep to working week Recognises the whole developer, and her needs for rest, recreation and her life outside work

16 Whole Team (on-site customer) Project is steered by a dedicated, full time customer who works with the team Customer develops user stories – broader than use cases – a scenario of use of the system, which delivers useable functionality Stand-up meeting every morning – 15 minutes reporting briefly on progress yesterday, plan for today, issues

17 Metaphor A common vision of what the system is doing Common vocabulary to provide a jargon for the whole team e.g. a system requiring matching would be a ‘dating agency’

18 Pair Programming All programming done in pairs – one is the driver – at the keyboard, the other is the coach, critic, support Roles switch Pairs switched about to spread knowledge of technology, XP and the application Novice/experienced programmer combination develops team learning

19 Simple Design Do the simplest thing possible to pass the tests Don’t anticipate future requirements ‘Spike’ – a simple end-to-end implementation to prove basic idea/technology

20 Design improvement Keeping the design simple requires constant improvement – spotting common code and re- factoring (generalising and normalizing)into one place. Re-testing checks improvement hasn’t broken the code Good general structures emerge from the continuous work, doesn’t need up-front investment in design (which often turns out to be wasted)

21 Collective Code Ownership cf. Gerry Weinberg and egoless programming (1971) All code belongs to the team Any member can fix code No waiting because writer is busy or ill

22 Coding Standards Standards make code more shareable Standards avoid personal styles e.g. bracket placement, indenting Good variable and method naming is preferable to comments

23 23 Predictive v Adaptive Some Key Issues Scope – breadth & depth of organisational effect Size – time, HR, number of functions, transaction volumes Complexity – systemic/organisational, deterministic/algorithmic Nature – of project, organisation, environment Volatility – requirements, markets, technologies

24 24 Predictive V Adaptive Adaptive –Uncertain or volatile requirements –Responsible, talented and motivated developers –Customer who understands and is willing to commit to the success of the project Predictive –A large development team (say 100+) –A fixed price, fixed scope contract Martin Fowler, The New Methodology, Found at


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