Agile software development
Overview
Agile is a set of principles for software development under which requirements and solutions evolve through the collaborative effort of self-organizing cross-functional teams. It advocates adaptive planning, evolutionary development, early delivery, and continual improvement, and it encourages flexible responses to change. These principles support the definition and continuing evolution of many software development methods.
History
The term "agile" was coined in the year 2001 when the Agile Manifesto was formulated. Agile methodologies have since been widely adopted by the software development industry. The Manifesto was a response to the rigid and documentation-heavy approaches such as the Waterfall model that were prevalent at the time.
Principles
The Agile Manifesto is based on twelve principles:
- Customer satisfaction by early and continuous delivery of valuable software.
- Welcome changing requirements, even in late development.
- Deliver working software frequently (weeks rather than months)
- Close, daily cooperation between business people and developers
- Projects are built around motivated individuals, who should be trusted
- Face-to-face conversation is the best form of communication (co-location)
- Working software is the primary measure of progress
- Sustainable development, able to maintain a constant pace
- Continuous attention to technical excellence and good design
- Simplicity—the art of maximizing the amount of work not done—is essential
- Best architectures, requirements, and designs emerge from self-organizing teams
- Regularly, the team reflects on how to become more effective, and adjusts accordingly
Methodologies
There are several Agile methodologies, each of which implements the principles of Agile in a unique way. Some of the most popular methodologies include:
- Scrum: An iterative and incremental Agile software development framework for managing product development. It defines "a flexible, holistic product development strategy where a development team works as a unit to reach a common goal".
- Kanban: A method for managing knowledge work with an emphasis on just-in-time delivery while not overloading the team members. In this approach, the process, from definition of a task to its delivery to the customer, is displayed for participants to see.
- Extreme Programming (XP): A software development methodology which is intended to improve software quality and responsiveness to changing customer requirements.
- Feature Driven Development (FDD): A model-driven short-iteration process that consists of five basic activities: Develop an Overall Model, Build a Features List, Plan By Feature, Design By Feature, Build By Feature.
Agile vs Traditional Development
Agile methodologies differ significantly from traditional waterfall methodologies. In a waterfall model, each phase of the software development life cycle is discrete, and there is no going back to a previous phase once it is complete. Agile methodologies, on the other hand, allow for iterative and incremental development. This means that software is developed and delivered in chunks, which allows for changes and revisions to be made at any point in the development process.
Benefits and Challenges
Agile methodologies offer a number of benefits over traditional software development methods. These include improved product quality, higher customer satisfaction, increased project control, reduced risks, and faster ROI. However, Agile also comes with its own set of challenges. These include the need for cultural change within the organization, the need for clear and constant communication among team members, and the need for experienced team members who are capable of self-management.