Agile Methods

Steven J Zeil:

Last modified: Dec 21, 2019


Agile methods are a modern approach to incremental development.

They emphasze:

This lesson is a discussion of the origins of Agile Development and a quick overview of the basic principles.

1 Agile as a Social Entity

1.1 Agile Development is

1.1.1 The Agile Manifesto

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.

1.1.2 The Twelve Principles of Agile Software

1) Our highest priority is to satisfy the customer through early and continuous delivery of valuable software.

2) Welcome changing requirements, even late in development. Agile processes harness change for the customer’s competitive advantage.

3) Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale.

4) Business people and developers must work together daily throughout the project.

5) Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done.

6) The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.

7) Working software is the primary measure of progress.

8) Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.

9) Continuous attention to technical excellence and good design enhances agility.

10) Simplicity – the art of maximizing the amount of work not done – is essential.

11) The best architectures, requirements, and designs emerge from self-organizing teams.

12) At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.

1.2 Variations

2 Common Practices of Agile Development


source: The Agile Alliance

2.1 Fundamentals

2.1.1 User stories

Key idea in all agile variations.

A user story is a mechanism for incremental requirements elicitation and analysis.

Stories are not Requirements

…despite the focus on functionality and non-functional characteristics.

Story Boards

2.1.2 Teams

2.1.3 Iterative development

2.1.4 Incremental development

2.1.5 Version Control

2.2 Common Intersections

2.2.1 Iteration Planning


Rate at which functionality (user stories) completed per iteration.

Task Board

Contains stories to be completed in current iteration

2.2.2 Sustainable pace

2.2.3 Meetings

2.2.4 Rules of Simplicity

(Kent Beck)

Each code unit

2.2.5 TDD

Test-Driven Development goes beyond our previously-cited “test first, code later” rule

  1. write a “single” unit test describing an unimplemented functionality
  2. run the test (it should fail at this stage)
  3. write “just enough” code to make the test pass
  4. refactor the code until it conforms to the rules of simplicity

The four steps above are repeated, adding new, tested functionality each time.

2.2.6 Simple Design

2.2.7 Familiar Intersections