LinuxHPC.org/Cluster Builder 1.3
Open-Source Software
Open-Source Software
By LinuxHPC.org and Cluster Resources
| Open-source Software |
|
Open-source software is computer software whose source code is available under a copyright license that permits users to study, change, and improve the software, and to redistribute it in modified or unmodified form. It is the most prominent example of open source development.
In his 1997 essay The Cathedral and the Bazaar[4], open-source evangelist Eric S. Raymond suggests a model for developing OSS known as the Bazaar model. Raymond likens the development of software by traditional methodologies to building a cathedral, "fully crafted by individual wizards or small bands of mages working in splendid isolation"[5]. He suggests that all software should be developed using the bazaar style, which he described as "a great babbling bazaar of differing agendas and approaches."
Open Source Model
In the Cathedral, model development takes place in a centralized way. Roles are clearly defined. Roles include people dedicated to designing (the architects), people responsible for managing the project, and people responsible for implementation. Traditional software engineering follows the Cathedral model. F.P. Brooks in his book The Mythical Man-Month advocates this sort of model. He goes further to say that in order to preserve the architectural integrity of a system, the system design should be done by as few architects as possible.
The Bazaar model, however, is different. In this model, roles are not clearly defined. Gregorio Robles[6] suggests that software developed using the Bazaar model should exhibit the following patterns:
Users should be treated as co-developers
The Bazaar model, however, is different. In this model, roles are not clearly defined. Gregorio Robles[6] suggests that software developed using the Bazaar model should exhibit the following patterns:
Users should be treated as co-developers
The users are treated like co-developers and so they should have access to the source code of the software. Furthermore users are encouraged to submit additions to the software, code fixes for the software, bug reports, documentation etc. Having more co-developers increases the rate at which the software evolves. Linus's law states that, "Given enough eyeballs all bugs are shallow." This means that if many users view the source code they will eventually find all bugs and suggest how to fix them. Note that some users have advanced programming skills, and furthermore, each user's machine provides an additional testing environment. This new testing environment offers that ability to find and fix a new bug.
Early Releases
The first version of the software should be released as early as possible so as to increase one's chances of finding co-developers early.
Frequent Integration
New code should be integrated as often as possible so as to avoid the overhead of fixing a large number of bugs at the end of the project life cycle. Some Open Source projects have nightly builds where integration is done automatically on a daily basis.
Several Versions
There should be at least two versions of the software. There should be a buggier version with more features and a more stable version with fewer features. The buggy version (also called the development version) is for users who want the immediate use of the latest features, and are willing to accept the risk of using code that is not yet thoroughly tested. The users can then act as co-developers, reporting bugs and providing bug fixes. The stable version offers the users fewer bugs and fewer features.
High Modularization
The general structure of the software should be modular allowing for parallel development.
Dynamic decision making structure
There is a need for a decision making structure, whether formal or informal, that makes strategic decisions depending on changing user requirements and other factors.
Most well-known OSS products follow the Bazaar model as suggested by Eric Raymond. These include projects such as Linux, Netscape, Apache, the GNU Compiler Collection, and Perl to mention a few.
Open source license
Open source licenses define the privileges and restrictions a licensor must follow in order to use, modify or redistribute the open source software. Open source software includes software with source code in the public domain and software distributed under an open-source license.
Examples of open source licenses include Apache License, BSD license, GNU General Public License, GNU Lesser General Public License, MIT License, Eclipse Public License and Mozilla Public License.
Open source movement
The open source movement is a large movement of computer scientists, programmers, and other computer users that advocates unrestricted access to the source code of software. It grew out of licenses such as BSD, the ubiquitous access to Unix source code at universities. The line between the open source movement and the free software movement is somewhat blurry. Both are founded in the hacker culture. Mostly, the Free software movement is based upon political and philosophical ideals, while open source proponents tend to focus on more pragmatic arguments. Openness is a term that has evolved now to refer to projects that are open to anyone and everyone to contribute to, before and/or after the actual programming. Both groups assert that this more open style of licensing allows for a superior software development process (when compared to closed source), and therefore that pursuing it is in line with rational self-interest. Free software advocates argue that "freedom" is a paramount merit that one should prefer even in any cases where proprietary software has some superior technical features.
Proponents of the open source development methodology claim that it is superior in a number of ways to the closed source method. Some, notably Eric S. Raymond, go so far as to suggest that the open source methodology is able to produce higher quality software than any other methodology or technique. Raymond has written a series of works exploring this theme, including The Cathedral and the Bazaar and Homesteading the Noosphere.
Open source advocates point out that as of the early 2000s, at least 90 percent of computer programmers are employed not to produce software for direct sale, but rather to design and customize software for other purposes, such as in-house applications. According to advocates, this statistic implies that the value of software lies primarily in its usefulness to the developer or developing organization, rather than in its potential sale value—consequently, there is usually no compelling economic reason to keep source code secret from competitors. Open-source advocates further argue that corporations frequently over-protect software in ways actually damaging to their own interests, for reasons ranging from mere institutional habit through reflexive territoriality to a rational but incorrect evaluation of the tradeoffs between collecting secrecy rent and the quality and market payoff of openness.
The 2001 film Antitrust portrayed the struggle of a small-time group of open source programmers against a large Microsoft-like closed-source corporation.
Open source is a term that is applied to the entire concept that the creation and organization of knowledge is best created through open and cooperative efforts—this movement, variously called "open content" or "free culture," has been expressly endorsed by advocates of OSS, including Linus Torvalds who said "The future is 'open source everything.'"
Open source versus closed source
The open source vs. closed source (alternatively called proprietary development) debate is sometimes heated.
Making money through traditional methods, such as sale of the use of individual copies and patent royalty payment, is more difficult and sometimes impractical with open-source software. Some closed-source advocates see open source software as damaging to the market of commercial software. This complaint is countered by a large number of alternative funding streams such as:
- giving the software for free and instead charge for installation and support (used by many Linux distributions)
- make the software available as open-source so that people will be more likely to purchase a related product or service you do sell (e.g. OpenOffice.org vs StarOffice)
- cost avoidance / cost sharing: many developers need a product, so it makes sense to share development costs (this is the genesis of the X Window System and the Apache web server)
Open source software versus free software
Open source software and free software are different terms for software which comes with certain rights, or freedoms, for the user. They describe two approaches and philosophies towards free software. Open source and Free software (or libre software) both describe software which is free from onerous licensing restrictions. It may be used, copied, studied, modified and redistributed without restriction. Free software is not the same as freeware, software available at zero price.
The definition of open source software was written to be almost identical to the free software definition. There are very few cases of software that is free software but is not open source software, and vice versa.The distinction between Open Source and Free Software is a matter of philosophy and approach. The difference in the terms is where they place the emphasis. Free software is defined in terms of giving the user freedom. This reflects the goal of the free software movement. Open source highlights that the source code is viewable to all and proponents of the term usually emphasize the quality of the software and how this is caused by the development models which are possible and popular among free and open source software projects.
Open source software and free software share an almost identical set of licenses. According to the FSF, the open source movement is philosophically distinct from the free software movement. The FSF's free software definition is more restrictive than the Open Source Definition (OSD). In practice, nearly all open-source licenses are also classed as free software licences by the FSF - which means they meet the free software definition. The difference is more a matter of philosophical emphasis. One exception is an early version of the Apple Public Source License, which was accepted by the OSI but rejected by the FSF because it did not allow private modified versions; this restriction was removed in later version of the license. There are now new versions that are approved by both the OSI and the FSF.
Free software licenses are not written exclusively by the FSF. The FSF and the OSI both list licenses which meet their respective definitions of free software.
The Open Source Initiative believes that more people will be convinced by the experience of freedom. The FSF believes that more people will be convinced by the concept of freedom. The FSF believes that knowledge of the concept is an essential requirement, insists on the use of the term free[7], and separates itself from the Open Source movement. The Open Source Initiative believes that free has three meanings: free as in beer, free as in freedom, and free as in unsellable. Open Source says nothing about the freedom to modify and redistribute, so it is being misused by people who think that source access without freedom is sufficient. This is the case with most of the licences that make up Microsoft's "shared source" initiative, and to a lesser extent with the "license-free" software of Daniel J. Bernstein.
All text used in this article is available under the GNU Free Documentation License. It uses material from the Wikipedia article "Open-source software".