Extreme Programming teams use a simple form of planning and tracking to decide what should be done next and to predict when the project will be done. Focused on business value, the team produces the software in a series of small fully-integrated releases that pass all the tests the Customer has defined. Extreme Programmers work together in pairs and as a group, with simple design and obsessively tested code, improving the design continually to keep it always just right for the current needs. The Extreme Programming team keeps the system integrated and running all the time. The programmers write all production code in pairs, and all work together all the time.
They code in a consistent style so that everyone can understand and improve all the code as needed. The Extreme Programming team shares a common and simple picture of what the system looks like. Everyone works at a pace that can be sustained indefinitely. All the contributors to an XP project sit together, members of one team. The team will of course have programmers. The team may include testers, who help the Customer define the customer acceptance tests.
Analysts may serve as helpers to the Customer, helping to define the requirements.
Software Engineering | Extreme Programming (XP)
There is commonly a coach, who helps the team keep on track, and facilitates the process. There may be a manager, providing resources, handling external communication, coordinating activities. None of these roles is necessarily the exclusive property of just one individual: Everyone on an XP team contributes in any way that they can. The best teams have no specialists, only general contributors with special skills. XP planning addresses two key questions in software development: predicting what will be accomplished by the due date, and determining what to do next.
The emphasis is on steering the project — which is quite straightforward — rather than on exact prediction of what will be needed and how long it will take — which is quite difficult. There are two key planning steps in XP, addressing these two questions:. Release Planning is a practice where the Customer presents the desired features to the programmers, and the programmers estimate their difficulty. With the cost estimates in hand, and with knowledge of the importance of the features, the Customer lays out a plan for the project.
Agile Project Management For Dummies, 2nd Edition
Even the first release plan is accurate enough for decision making, however, and XP teams revise the release plan regularly. Iteration Planning is the practice whereby the team is given direction every couple of weeks. During Iteration Planning, the Customer presents the features desired for the next two weeks. The programmers break them down into tasks, and estimate their cost at a finer level of detail than in Release Planning. Based on the amount of work accomplished in the previous iteration, the team signs up for what will be undertaken in the current iteration.
These planning steps are very simple, yet they provide very good information and excellent steering control in the hands of the Customer. Every couple of weeks, the amount of progress is entirely visible. This focus on visibility results in a nice little paradox: on the one hand, with so much visibility, the Customer is in a position to cancel the project if progress is not sufficient.
Extreme Programming Practices in Agile - A Practical Guide for Project Managers and nTaskers
On the other hand, progress is so visible, and the ability to decide what will be done next is so complete, that XP projects tend to deliver more of what is needed, with less pressure and stress. As part of presenting each desired feature, the XP Customer defines one or more automated acceptance tests to show that the feature is working. The team builds these tests and uses them to prove to themselves, and to the customer, that the feature is implemented correctly. Automation is important because in the press of time, manual tests are skipped.
Extreme Programming Practices in Agile – A Practical Guide for Project Managers and nTaskers
The best XP teams treat their customer tests the same way they do programmer tests : once the test runs, the team keeps it running correctly thereafter. This means that the system only improves, always notching forward, never backsliding.
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First, the team releases running, tested software, delivering business value chosen by the Customer, every iteration. The Customer can use this software for any purpose, whether evaluation or even release to end users highly recommended. The most important aspect is that the software is visible, and given to the customer, at the end of every iteration.
Ward Cunningham : design pattern pioneer, and software consultant at Cunningham and Cunningham, Inc.
Don Wells : he is a leader in the field of artificial intelligence and a champion of XP. Martin Fowler : software engineer, consultant, speaker, and writer. Agile Manifesto: this historically significant framework was part of a movement to create a set of criteria to improve software development methods. This manifesto is one of the most successful guides for software engineering.
SmallTalk : this paper gives you an overview of the SmallTalk computer language, which played an important role in the story of software engineering, and XP. Learn about it here from Agile Aliance. Resources The links below will take you to resources related to Extreme Programming.
Agile Process : another gentle introduction to a heavy concept written by Don Wells. Refactoring : refactoring is an important core skill of Agile Development.
This website has explanations, exercises, and links to more resources. The Principles of Agile Development: this gives you a broad view on the basic concepts of Agile Development. Pair Programming : This is one of the most important aspects of extreme programming is pair programming.
Lean IT summit : an annual conference on applying the principles of Lean manufacturing to software engineering. XP Continues to Leave Its Mark The principles and values introduced by extreme programming revolutionized software development. Extreme Programming emphasizes teamwork. Managers, customers, and developers are all equal partners in a collaborative team. Extreme Programming implements a simple, yet effective environment enabling teams to become highly productive.
The team self-organizes around the problem to solve it as efficiently as possible. Extreme Programming improves a software project in five essential ways; communication, simplicity, feedback, respect, and courage.
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Extreme Programmers constantly communicate with their customers and fellow programmers. They keep their design simple and clean. They get feedback by testing their software starting on day one. They deliver the system to the customers as early as possible and implement changes as suggested. Every small success deepens their respect for the unique contributions of each and every team member.