Extreme Programming - Wikipedia

Kent Beck developed extreme programming during his work on the Chrysler Comprehensive Compensation System (C3) payroll project.[5] Beck became the C3 project leader in March 1996. He began to refine the development methodology used in the project and wrote a book on the methodology (Extreme Programming Explained, published in October 1999).[5] Chrysler cancelled the C3 project in February 2000, after seven years, when Daimler-Benz acquired the company.[6] Ward Cunningham was another major influence on XP.

Many extreme-programming practices have been around for some time; the methodology takes "best practices" to extreme levels. For example, the "practice of test-first development, planning and writing tests before each micro-increment" was used as early as NASA's Project Mercury, in the early 1960s.[7] To shorten the total development time, some formal test documents (such as for acceptance testing) have been developed in parallel with (or shortly before) the software being ready for testing. A NASA independent test group can write the test procedures, based on formal requirements and logical limits, before programmers write the software and integrate it with the hardware. XP takes this concept to the extreme level, writing automated tests (sometimes inside software modules) which validate the operation of even small sections of software coding, rather than only testing the larger features.

Origins

Two major influences shaped software development in the 1990s:

• Internally, object-oriented programming replaced procedural programming as the programming paradigm favored by some developers.
• Externally, the rise of the Internet and the dot-com boom emphasized speed-to-market and company growth as competitive business factors.

Rapidly changing requirements demanded shorter product life-cycles, and often clashed with traditional methods of software development.

The Chrysler Comprehensive Compensation System (C3) started in order to determine the best way to use object technologies, using the payroll systems at Chrysler as the object of research, with Smalltalk as the language and GemStone as the data access layer. Chrysler brought in Kent Beck,[5] a prominent Smalltalk practitioner, to do performance tuning on the system, but his role expanded as he noted several problems with the development process. He took this opportunity to propose and implement some changes in development practices - based on his work with his frequent collaborator, Ward Cunningham. Beck describes the early conception of the methods:[8]

The first time I was asked to lead a team, I asked them to do a little bit of the things I thought were sensible, like testing and reviews. The second time there was a lot more on the line. I thought, "Damn the torpedoes, at least this will make a good article," [and] asked the team to crank up all the knobs to 10 on the things I thought were essential and leave out everything else.

Beck invited Ron Jeffries to the project to help develop and refine these methods. Jeffries thereafter acted as a coach to instill the practices as habits in the C3 team.

Information about the principles and practices behind XP disseminated to the wider world through discussions on the original wiki, Cunningham's WikiWikiWeb. Various contributors discussed and expanded upon the ideas, and some spin-off methodologies resulted (see agile software development). Also, XP concepts have been explained, for several years, using a hypertext system map on the XP website at http://www.extremeprogramming.org c. 1999.

Beck edited a series of books on XP, beginning with his own Extreme Programming Explained (1999, ISBN 0-201-61641-6), spreading his ideas to a much larger audience. Authors in the series went through various aspects attending XP and its practices. The series included a book critical of the practices.