Open Source Computing

Open source computing refers to software distributed along with the source code. The source code is the human-readable instructions that define the operation of an application. Releasing the source ensures that anyone can modify the software, either to improve it or to alter its functionality. By contrast, closed source or proprietary software is not released as source code but as compiled, executable files. Proprietary software is more difficult to reverse engineer, and supporters argue that it is more secure since vulnerabilities cannot be read from the source code. On the other hand, open source advocates argue that source code can be more thoroughly checked for bugs and security flaws when more developers are able to study and modify it. Releasing a project as open source generally involves releasing it under an open license that defines user rights to the code. Open source software can refer to individual applications or entire operating systems. After a review of the early years of open source software creation, this entry highlights the development of the foundational operating system and programs and concludes with some benefits and potential drawbacks of open source computing with regard to software and system security.

The open source movement began with Richard Stallman, a researcher at Massachusetts Institute of Technology’s Artificial Intelligence Lab. As software companies began to assert intellectual property rights over their code, Stallman drafted the first version of the GNU General Public License (GNU GPL or simply GPL). The GPL is a software copyright license that asserted Stallman’s Four Software Freedoms: (1) to use, (2) to study, (3) to share, and (4) to modify the code. These four freedoms have come to define the sense of “free” in “free and open source software,” which is another label widely embraced by the open source community. The most remarkable feature of the GPL is its “viral” quality. The GPL states that any computer code interacting with GPL code must be GPL compatible, which is to say that it must be licensed in such a way as to protect the Four Software Freedoms. The viral quality of the GPL creates an ecosystem of open source software as it is not permitted to combine proprietary and open source code. Rather than stifling open source development, this feature of the GPL has given rise to a wide range of open source projects, including stand-alone applications and operating systems, all organizing around overlapping communities of users and developers.

Free and open source software advocate Eric S. Raymond characterizes open source development models in terms of the “cathedral” and the “bazaar.” Proprietary software, like the building of a cathedral, requires the work of many hands but is centrally designed and organized. Open source development more closely resembles the distributed and self-organized efforts that characterize the chaotic sprawling market activity of a bazaar. Since anyone can read the source code and release modified versions, open source development exploits the community of users and codevelopers to write, refine, and update software. Projects that attract attention develop large communities, but some small projects will be maintained by just a handful of volunteers. While larger projects tend to demonstrate more organization, open source computing is to some extent defined by distributed development models.

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