The Cathedral and the Bazaar

The Cathedral and the Bazaar: Musings on Linux and Open Source by an Accidental Revolutionary (abbreviated CatB) is an essay, and later a book, by Eric S. Raymond on software engineering methods, based on his observations of the Linux kernel development process and his experiences managing an open source project, fetchmail. It examines the struggle between top-down and bottom-up design. The essay was first presented by Raymond at the Linux Kongress on May 27, 1997 in Würzburg (Germany) and was published as the second chapter of the sametitled book in 1999. The illustration on the cover of the book is a 1913 painting by Lyubov Popova titled Composition with Figures and belongs to the collection of the State Tretyakov Gallery. The book was released under the Open Publication License v2.0 in 1999. The essay contrasts two different free software development models: The Cathedral model, in which source code is available with each software release, but code developed between releases is restricted to an exclusive group of software developers. GNU Emacs and GCC were presented as examples. The Bazaar model, in which the code is developed over the Internet in view of the public. Raymond credits Linus Torvalds, leader of the Linux kernel project, as the inventor of this process. Raymond also provides anecdotal accounts of his own implementation of this model for the Fetchmail project. The essay's central thesis is Raymond's proposition that "given enough eyeballs, all bugs are shallow" (which he terms Linus's law): the more widely available the source code is for public testing, scrutiny, and experimentation, the more rapidly all forms of bugs will be discovered. In contrast, Raymond claims that an inordinate amount of time and energy must be spent hunting for bugs in the Cathedral model, since the working version of the code is available only to a few developers. Raymond points to 19 "lessons" learned from various software development efforts, each describing attributes associated with good practice in open source software development: Every good work of software starts by scratching a developer's personal itch.