Agile software development

Agile software development is a group of software development methods based on iterative and incremental development, where requirements and solutions evolve through collaboration between self-organizing, cross-functional teams. It promotes adaptive planning, evolutionary development and delivery, a time-boxed iterative approach, and encourages rapid and flexible response to change. It is a conceptual framework that promotes foreseen tight iterations throughout the development cycle.
The Agile Manifesto^[1] introduced the term in 2001. Since then, the Agile Movement, with all its values, principles, methods, practices, tools, champions and practitioners, philosophies and cultures, has significantly changed the landscape of the modern software engineering and commercial software development in the Internet era

The Agile Manifesto

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

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

Agile principles

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. Working software is the principal measure of progress
5. Sustainable development, able to maintain a constant pace
6. Close, daily cooperation between business people and developers
7. Face-to-face conversation is the best form of communication (co-location)
8. Projects are built around motivated individuals, who should be trusted
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

 Scrum team: A typical scrum team has between five and nine people, but Scrum projects can easily scale into the hundreds. However, Scrum can easily be used by one-person teams and often is. This team does not include any of the traditional software engineering roles such as programmer, designer, tester or architect. Everyone on the project works together to complete the set of work they have collectively committed to complete within a sprint. Scrum teams develop a deep form of camaraderie and a feeling that “we’re all in this together.”

ScrumMaster: The ScrumMaster is responsible for making sure the team is as productive as possible. The ScrumMaster does this by helping the team use the Scrum process, by removing impediments to progress, by protecting the team from outside, and so on.

Sprint planning meeting: At the start of each sprint, a sprint planning meeting is held, during which the product owner presents the top items on the product backlog to the team. The Scrum team selects the work they can complete during the coming sprint. That work is then moved from the product backlog to a sprint backlog, which is the list of tasks needed to complete the product backlog items the team has committed to complete in the sprint.
Daily Scrum: Each day during the sprint, a brief meeting called the daily scrum is conducted. This meeting helps set the context for each day’s work and helps the team stay on track. All team members are required to attend the daily scrum.
Sprint review meeting: At the end of each sprint, the team demonstrates the completed functionality at a sprint review meeting, during which, the team shows what they accomplished during the sprint. Typically, this takes the form of a demonstration of the new features, but in an informal way; for example, PowerPoint slides are not allowed. The meeting must not become a task in itself nor a distraction from the process.
Sprint retrospective: Also at the end of each sprint, the team conducts a sprint retrospective, which is a meeting during which the team (including its ScrumMaster and product owner) reflect on how well Scrum is working for them and what changes they may wish to make for it to work even better.

What is Scrum?

Scrum is an agile way to manage a project, usually software development. Agile software development with Scrum is often perceived as a methodology; but rather than viewing Scrum as methodology, think of it as a framework for managing a process.
In the agile Scrum world, instead of providing complete, detailed descriptions of how everything is to be done on a project, much of it is left up to the Scrum software development team. This is because the team will know best how to solve the problem they are presented.
This is why in Scrum development, for example, a sprint planning meeting is described in terms of the desired outcome (a commitment to a set of features to be developed in the next sprint) instead of a set of Entry criteria, Task definitions, Validation criteria, Exit criteria (ETVX) and so on, as would be provided in most methodologies.
Scrum relies on a self-organizing, cross-functional team. The scrum team is self-organizing in that there is no overall team leader who decides which person will do which task or how a problem will be solved. Those are issues that are decided by the team as a whole.

SCRUM is a loose set of guidelines that govern the development process of a product, from its design stages to its completion. It aims to cure some common failures of the typical development process, such as:

• Chaos due to changing requirements - the real or perceived requirements of a project usually change drastically from the time the product is designed to when it is released. Under most product development methods, all design is done at the beginning of the project, and then no changes are allowed for or made when the requirements change.
• Unrealistic estimates of time, cost, and quality of the product - the project management and the developers tend to underestimate how much time and resources a project will take, and how much functionality can be produced within those constraints. In actuality, this usually cannot be accurately predicted at the beginning of the development cycle.
• Developers are forced to lie about how the project is progressing - When management underestimates the time and cost needed to reach a certain level of quality, the developers must either lie about how much progress has been made on the product, or face the indignation of the management.

SCRUM has been successfully employed by hundreds of different companies in many different fields, with outstanding results.

You will find many similarities between SCRUM and Extreme Programming, but one of the major differences is that SCRUM is a fairly general set of guidelines that govern the development process of a product. For this reason, it is often used as a "wrapper" for other methodologies, such as XP or CMM (Capability Maturity Model) - that is, it is used to guide the overall process of development when using these other methodologies.

SCRUM Values

The SCRUM values are derived from the Agile values of software development.

• Individuals and interactions over processes and tools - processes and tools are helpful, but they will do you no good if the team does not communicate and collaborate in a constructive fashion.
• Working software over comprehensive documentation - documentation is important, but what's most important is to have working software.
• Customer collaboration over contract negotiation - you are not just looking to get a contract and get money that way - you are solving the customer's problem.
• Responding to change over following a plan - if the requirements or perceived requirements changed, so should the plans and design.

The SCRUM Process

Figure 1: General SCRUM Process

The scrum process has 3 main phases.

Planning

In this phase, the project is planned and high-level design decisions are made.

Sprint Cycle

Figure 2: The SCRUM Sprint Cycle

The sprint cycle is an iterative cycle of about 3-4 weeks, in which the actual development of the product is done. It starts out with a Sprint Planning Meeting to decide what will be done in the current sprint. Then the development is done. A sprint is closed with a Sprint Review Meeting where the progress made in the last sprint is demonstrated, the sprint is reviewed, and adjustments are made to the project as necessary.

The sprint cycle is repeated until the product's development is complete. The product is complete when the variables of time, quality, competition, and cost are at a balance.

• Develop the product further - implement, test, and document.
• Wrap up the work - get it ready to be evaluated and integrated.
• Review the work done in this sprint.
• Adjust for any changes in requirements or plans.

Closure

In this phase, the product's development is brought to a close, and the product is released.

The Scrum Team

The SCRUM team consists of 2 groups - the interested team, which consists of people who are interested, but who will not be doing the work, and the working team - people who are interested, and will be doing the work on the project.

A team typically has no more than 6-9 working members, although SCRUM has been successfully used with more members. If there are more members than manageable, the project should be broken into multiple sub-projects, each focusing on one, self-contained area of work (one for QA, one for documentation, etc.). There should be people to act as bridges - that is, to attend the meetings of more than one SCRUM team, and act as a communication bridge between the teams. Members of teams that are closely related/involved with each other should sit in on the other teams' SCRUM meetings.

The leader (SCRUM Master)

The team's leader is called the Scrum Master. He should be one of the members of the working team - that is, he should be one of the people who is actually doing the work on the project. The SCRUM Master measures progress, removes impediments, and leads the team meetings.

Commonly Used Terms

Sprint

The product is developed in a series of 1-to-4-week iterations, or sprints. Before a sprint is begun, a Sprint Planning Meeting is held to determine what features are to be implemented in that sprint. The sprint has 4 major steps:

• Develop the product further - implement, test, and document.
• Wrap up the work - get it ready to be evaluated and integrated.
• Review the work done in this sprint.
• Adjust for any changes in requirements or plans.

Product Backlog

A prioritized list of all the desired changes to the product being developed, put together by the product owner. See Figure 2.

Sprint BackLog

A list with items that will be completed in the current sprint, taken from the product backlog. See Figure 2.

Daily SCRUM Meeting

A 15-minute SCRUM meeting is held every day. The SCRUM Master asks the three questions, and all members of the team and interested parties take part and give feedback. The meeting should be held at the same place every time, so that people know where to go.

Unit Testing

A unit test is an automated test that ensures that the functionality required for a certain area of a project is implemented, and that there are no breaking changes that have not been taken into consideration. Seehttp://www.xprogramming.com/software.htm for a list of unit testing frameworks for different languages/platforms.

Impediment

Impediments are things that get in the way of the progress of the project. The SCRUM Master is responsible to look for and remove these obstacles so that they do not slow down or impair the project.

3 Questions

The Scrum Master asks the developers 3 important questions at every SCRUM meeting:

1. What have you accomplished since the last meeting?
2. Are there any obstacles in the way of meeting your goal?
3. What will you accomplish before the next meeting?

Product Owner

The person who commissions the project, and defines the requirements and priorities for the product.

Sprint Planning Meeting

A meeting at the beginning of a sprint where the sprint is planned. Items from the Product Backlog are selected to be completed in the sprint, based on the priorities set by the Product Owner.

Sprint Review Meeting

A sprint is closed with a Sprint Review Meeting where the progress made in the last sprint is demonstrated, the sprint is reviewed, and adjustments are made to the project as necessary.

Scrum?

Scrum is an Agile framework for completing complex projects. Scrum originally was formalized for software development projects, but it works well for any complex, innovative scope of work. The possibilities are endless. The Scrum framework is deceptively simple.

The Scrum framework

• A product owner creates a prioritized wish list called a product backlog.
• During sprint planning, the team pulls a small chunk from the top of that wish list, a sprint backlog, and decides how to implement those pieces.
• The team has a certain amount of time — a sprint (usually two to four weeks) — to complete its work, but it meets each day to assess its progress (daily Scrum).
• Along the way, the ScrumMaster keeps the team focused on its goal.
• At the end of the sprint, the work should be potentially shippable: ready to hand to a customer, put on a store shelf, or show to a stakeholder.
• The sprint ends with a sprint review and retrospective.
• As the next sprint begins, the team chooses another chunk of the product backlog and begins working again.

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