Agile software development

Agile software development is a group of software development methods in which requirements and solutions evolve through collaboration between self-organizing, cross-functional teams. It promotes adaptive planning, evolutionary development, early delivery, continuous improvement and encourages rapid and flexible response to change. It is a conceptual framework that focuses on frequently delivering small increments of working software.

The Agile Manifesto,^[1] which first laid out the underlying concepts of Agile development, introduced the term in 2001.

History[edit]

Predecessors[edit]

Incremental software development methods have been traced back to 1957.^[2] In 1974, a paper by E. A. Edmonds introduced an adaptive software development process.^[3] Concurrently and independently, the same methods were developed and deployed by the New York Telephone Company's Systems Development Center under the direction of Dan Gielan. In the early 1970s,Tom Gilb started publishing the concepts of Evolutionary Project Management (EVO), which has evolved into Competitive Engineering.^[4] During the mid to late 1970s, Gielan lectured extensively throughout the U.S. on this methodology, its practices, and its benefits.

So-called lightweight agile software development methods evolved in the mid-1990s as a reaction against the heavyweight waterfall-oriented methods, which were characterized by their critics as being heavily regulated, regimented, micromanaged and over-incremental approaches to development.

Proponents of lightweight agile methods contend that they are returning to development practices that were present early in the history of software development.^[2]

Early implementations of agile methods include Rational Unified Process (1994), Scrum (1995), Crystal Clear, Extreme Programming (1996), Adaptive Software Development, Feature Driven Development (1997), and Dynamic Systems Development Method (DSDM) (1995). These are now collectively referred to as agile methodologies, after the Agile Manifesto was published in 2001.^[5]

The Agile Manifesto[edit]

In February 2001, 17 software developers (see below) met at the Snowbird, Utah resort, to discuss lightweight development methods. They published the Manifesto for Agile Software Development ^[1] to define the approach now known as agile software development. Some of the manifesto's authors formed the Agile Alliance, a non-profit organization that promotes software development according to the manifesto's values and principles.

Agile values[edit]

The Agile Manifesto reads, in its entirety, as follows:

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]

Kent Beck	James Grenning	Robert C. Martin
Mike Beedle	Jim Highsmith	Steve Mellor
Arie van Bennekum	Andrew Hunt	Ken Schwaber
Alistair Cockburn	Ron Jeffries	Jeff Sutherland
Ward Cunningham	Jon Kern	Dave Thomas
Martin Fowler	Brian Marick

© 2001, the above authors. This declaration may be freely copied in any form, but only in its entirety through this notice.

The meanings of the manifesto items on the left within the agile software development context are:

· Individuals and interactions – in agile development, self-organization and motivation are important, as are interactions like co-location and pair programming.

· Working software – working software will be more useful and welcome than just presenting documents to clients in meetings.

· Customer collaboration – requirements cannot be fully collected at the beginning of the software development cycle, therefore continuous customer or stakeholder involvement is very important.

· Responding to change – agile development is focused on quick responses to change and continuous development.^[6]

Introducing the manifesto on behalf of the Agile Alliance, Jim Highsmith commented that the Agile movement was not opposed to methodology:

The Agile movement is not anti-methodology, in fact, many of us want to restore credibility to the word methodology. We want to restore a balance. We embrace modeling, but not in order to file some diagram in a dusty corporate repository. We embrace documentation, but not hundreds of pages of never-maintained and rarely-used tomes. We plan, but recognize the limits of planning in a turbulent environment. Those who would brand proponents of XP or SCRUM or any of the other Agile Methodologies as "hackers" are ignorant of both the methodologies and the original definition of the term hacker.

—Jim Highsmith, History: The Agile Manifesto^[7]

Agile principles[edit]

The Agile Manifesto is based on twelve principles:^[8]

1. Customer satisfaction by rapid delivery of useful software

2. Welcome changing requirements, even late in development

3. Working software is delivered frequently (weeks rather than months)

4. Close, daily cooperation between business people and developers

5. Projects are built around motivated individuals, who should be trusted

6. Face-to-face conversation is the best form of communication (co-location)

7. Working software is the principal measure of progress

8. Sustainable development, able to maintain a constant pace

9. Continuous attention to technical excellence and good design

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

11. Self-organizing teams

12. Regular adaptation to changing circumstances

Evolutions[edit]

Later, Ken Schwaber with others founded the Scrum Alliance and created the Certified Scrum Master programs and its derivatives. Schwaber left the Scrum Alliance in the fall of 2009, and founded Scrum.org.

In 2005, a group headed by Alistair Cockburn and Jim Highsmith wrote an addendum of project management principles, the Declaration of Interdependence,^[9] to guide software project management according to agile development methods.

In 2009, a movement spearheaded by Robert C Martin wrote an extension of software development principles, the Software Craftsmanship Manifesto, to guide agile software development according to professional conduct and mastery.

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