Fork (software development)
In
Free and open-source software is that which, by definition, may be forked from the original development team without prior permission, and without violating copyright law. However, licensed forks of proprietary software (e.g. Unix) also happen.
Etymology
The word "fork" has been used to mean "to divide in branches, go separate ways" as early as the 14th century.[2] In the software environment, the word evokes the fork system call, which causes a running process to split itself into two (almost) identical copies that (typically) diverge to perform different tasks.[3]
In the context of software development, "fork" was used in the sense of creating a revision control "
Creating a branch "forks off" a version of the program.
The term was in use on Usenet by 1983 for the process of creating a subgroup to move topics of discussion to.[5]
"Fork" is not known to have been used in the sense of a community schism during the origins of Lucid Emacs (now XEmacs) (1991) or the Berkeley Software Distributions (BSDs) (1993–1994); Russ Nelson used the term "shattering" for this sort of fork in 1993, attributing it to John Gilmore.[6] However, "fork" was in use in the present sense by 1995 to describe the XEmacs split,[7] and was an understood usage in the GNU Project by 1996.[8]
Forking of free and open-source software
Free and open-source software may be legally forked without prior approval of those currently developing, managing, or distributing the software per both The Free Software Definition and The Open Source Definition:[9]
The freedom to distribute copies of your modified versions to others (freedom 3). By doing this, you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.
3. Derived Works: The license must allow modifications and derived works, and must allow them to be distributed under the same terms as the license of the original software.
In free software, forks often result from a schism over different goals or personality clashes. In a fork, both parties assume nearly identical code bases, but typically only the larger group, or whoever controls the web site, will retain the full original name and the associated user community. Thus, there is a reputation penalty associated with forking.[9] The relationship between the different teams can be cordial or very bitter. On the other hand, a friendly fork or a soft fork is a fork that does not intend to compete, but wants to eventually merge with the original.
Eric S. Raymond, in his essay Homesteading the Noosphere,[12] stated that "The most important characteristic of a fork is that it spawns competing projects that cannot later exchange code, splitting the potential developer community". He notes in the Jargon File:[13]
Forking is considered a Bad Thing—not merely because it implies a lot of wasted effort in the future, but because forks tend to be accompanied by a great deal of strife and acrimony between the successor groups over issues of legitimacy, succession, and design direction. There is serious social pressure against forking. As a result, major forks (such as the Gnu-Emacs/XEmacs split, the fissioning of the 386BSD group into three daughter projects, and the short-lived GCC/EGCS split) are rare enough that they are remembered individually in hacker folklore.
David A. Wheeler notes[9] four possible outcomes of a fork, with examples:
- The death of the fork. This is by far the most common case. It is easy to declare a fork, but considerable effort to continue independent development and support.
- A re-merging of the fork (e.g., egcs becoming "blessed" as the new version of GNU Compiler Collection.)
- The death of the original (e.g. the X.Org Server succeeding and XFree86 dying.)
- Successful branching, typically with differentiation (e.g., OpenBSD and NetBSD.)
Forks often restart version numbering from numbers typically used for initial versions of programs like 0.0.1, 0.1, or 1.0 even if the original software was at another version such as 3.0, 4.0, or 5.0. An exception is sometimes made when the forked software is designed to be a drop-in replacement for the original project, e.g. MariaDB for MySQL[15] or LibreOffice for OpenOffice.org.
The
Forking proprietary software
In
A notable proprietary fork not of this kind is the many varieties of proprietary Unix—almost all derived from AT&T Unix under license and all called "Unix", but increasingly mutually incompatible.[19] See Unix wars.
See also
- List of software forks
- Source port
- Downstream (software development)
- Group decision-making
- Modular programming
- Custom software
- Personalization
- Team effectiveness
- ROM Hacking
References
- ^ "Schism", with its connotations, is a common usage, e.g.
- "the Lemacs/FSFmacs schism" Archived 30 November 2009 at the Wayback Machine (Jamie Zawinski, 2000)
- "Behind the KOffice split" Archived 6 July 2013 at the Wayback Machine (Joe Brockmeier, Linux Weekly News, 2010-12-14)
- "Copyright assignment – once bitten, twice shy" Archived 30 March 2012 at the Wayback Machine (Richard Hillesley, H-Online, 2010-08-06)
- "Forking is a feature" Archived 29 February 2012 at the Wayback Machine (Anil Dash, 2010-09-10)
- "The Great Software Schism" Archived 6 January 2012 at the Wayback Machine (Glyn Moody, Linux Journal, 2006-09-28)
- "To Fork Or Not To Fork: Lessons From Ubuntu and Debian" Archived 26 February 2012 at the Wayback Machine (Benjamin Mako Hill, 2005).
- ^ Entry 'fork' in Online Etymology Dictionary Archived 25 May 2012 at the Wayback Machine
- (PDF) from the original on 2 December 2013. Retrieved 20 October 2012.
- ^ Allman, Eric. "An Introduction to the Source Code Control System." Archived 6 November 2014 at the Wayback Machine Project Ingres, University of California at Berkeley, 1980.
- ^ Can somebody fork off a "net.philosophy"? (John Gilmore, net.misc, 18 January 1983)
- ^ Shattering — good or bad? (Russell Nelson, gnu.misc.discuss, 1 October 1993)
- ^ Re: Hey Franz: 32K Windows SUCK!!!!! (Bill Dubuque, cu.cs.macl.info, 21 September 1995)
- ^ Lignux? (Marcus G. Daniels, gnu.misc.discuss, 7 June 1996)
- ^ a b c Why Open Source Software / Free Software (OSS/FS, FLOSS, or FOSS)? Look at the Numbers!: Forking Archived 5 April 2006 at the Wayback Machine (David A. Wheeler)
- ^ Stallman, Richard. "The Free Software Definition". Free Software Foundation. Archived from the original on 14 October 2013. Retrieved 15 October 2013.
- ^ "The Open Source Definition". The Open Source Initiative. 7 July 2006. Archived from the original on 15 October 2013. Retrieved 15 October 2013.
- ^ Raymond, Eric S. (15 August 2002). "Promiscuous Theory, Puritan Practice". catb.org. Archived from the original on 6 October 2006.
- ^ Forked Archived 8 November 2011 at the Wayback Machine (Jargon File), first added to v4.2.2 Archived 14 January 2012 at the Wayback Machine, 20 August 2000)
- hdl:10138/153135.
Where practitioners have previously had rather narrow definitions of a fork, [...] the term now appears to be used much more broadly. Actions that would traditionally have been called a branch, a new distribution, code fragmentation, a pseudo-fork, etc. may all now be called forks by some developers. This appears to be in no insignificant part due to the broad definition and use of the term fork by GitHub.
- ^ Forked a project, where do my version numbers start? Archived 26 August 2011 at the Wayback Machine
- ^ EnterpriseDB Archived 13 November 2006 at the Wayback Machine
- ^ Fujitsu Supported PostgreSQL Archived 20 August 2006 at the Wayback Machine
- ^ Netezza Archived 13 November 2006 at the Wayback Machine
- ^ Fear of forking Archived 17 December 2012 at the Wayback Machine – An essay about forking in free software projects, by Rick Moen
External links
- Right to Fork at Meatball Wiki
- A PhD examining forking: (Nyman, 2015) Archived 16 July 2023 at the Wayback Machine "Understanding Code Forking in Open Source Software – An examination of code forking, its effect on open source software, and how it is viewed and practiced by developers"