Agile Methodology: History and Principles
There can be a lot of confusion and differences of opinion about what the term “agile" really means. When used in the context of software development, many people refer to it as a “methodology," others say it's a “framework" and still others consider it a “philosophy."
There are debates about assessments that will rate “how agile" an organization is or declare that a particular practice is decidedly “not agile" as though the "agile police" may come through and issue some kind of penalty for poor practices.
In fact, the tenets, principles and methodologies that are considered “agile" were in existence before the word “agile" was used to describe them. However, the word “agile" became an umbrella phrase used for a variety of techniques, philosophies, values and principles that were described as part of the Agile Manifesto.
In February 2001, a group of 17 thought leaders in software development gathered in Snowbird, Utah, to discuss adaptive software development. The leaders were experts in a variety of software methodologies that were iterative and adaptive and considered “lightweight" in comparison to the highly prescriptive waterfall methodology.
The leaders wanted to describe principles that would allow the development community to have more autonomy and not be bogged down with unnecessary bureaucratic process.
Though the group did not create a new methodology, it came to consensus on the value statements, and documented them in what is called 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.
This simple manifesto reminds leaders that there is a need for balance. Above all, the Agile Manifesto reminds us that people are at the heart of successful software development. And this is the foundation for the agile methodology.
12 Agile Principles
The authors of the Agile Manifesto agreed upon
12 principles on which the manifesto was based:
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.
These principles do not necessarily spell out the steps to an agile methodology, but rather are characteristics that are found in software methodologies and techniques that are now described as agile.
Agile Software Development Methodologies
There are a variety of software development methodologies that embrace the values and principles described in the Agile Manifesto, and are considered “agile" in nature.
In 2001, when the thought leaders convened, there were a number of methodologies that were already in existence that fell into the realm of practicing agile principles. These included:
- From 1994: Unified process and dynamic systems and development method (DSDM)
- From 1995: Scrum
- From 1996: Crystal clear and extreme programming (XP)
- From 1997: Adaptive software development and feature-driven development
Since 2001, Scrum has grown to become the most popular agile methodology associated with the agile movement, so much so that many people use the terms Scrum and agile interchangeably.
Though agile methodologies other than Scrum are still being used, rather than following one particular methodology to the letter, it is more common for teams to adapt agile techniques that may have originated from different methodologies, and mix and match techniques, creating an agile methodology that best suits the organization.
For example, even though user stories were originally used in XP as a way to document requirements, they are commonly used on Scrum teams as well.