A screenshot of Linux Mint running the Xfce desktop environment, Mozilla Firefox browsing Wikipedia powered by MediaWiki, a calculator program, the built-in calendar, Vim, GIMP, and the VLC media player, all of which are open-source software.
Open-source software (OSS) is a type of computer software in which source code is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software to anyone and for any purpose. Open-source software may be developed in a collaborative public manner. Open-source software is a prominent example of open collaboration.
Open-source software development can bring in diverse perspectives beyond those of a single company. A 2008 report by the Standish Group
stated that adoption of open-source software models has resulted in
savings of about $60 billion (£48 billion) per year for consumers.
History
End of 1990s: Foundation of the Open Source Initiative
In
the early days of computing, programmers and developers shared software
in order to learn from each other and evolve the field of computing.
Eventually, the open-source notion moved to the way side of
commercialization of software in the years 1970–1980. However, academics
still often developed software collaboratively. For example, Donald Knuth in 1979 with the TeX typesetting system or Richard Stallman in 1983 with the GNU operating system. In 1997, Eric Raymond published The Cathedral and the Bazaar,
a reflective analysis of the hacker community and free-software
principles. The paper received significant attention in early 1998, and
was one factor in motivating Netscape Communications Corporation to release their popular Netscape Communicator Internet suite as free software. This source code subsequently became the basis behind SeaMonkey, Mozilla Firefox, Thunderbird and KompoZer.
Netscape's act prompted Raymond and others to look into how to bring the Free Software Foundation's
free software ideas and perceived benefits to the commercial software
industry. They concluded that FSF's social activism was not appealing to
companies like Netscape, and looked for a way to rebrand the free software movement to emphasize the business potential of sharing and collaborating on software source code. The new term they chose was "open source", which was soon adopted by Bruce Perens, publisher Tim O'Reilly, Linus Torvalds, and others. The Open Source Initiative was founded in February 1998 to encourage use of the new term and evangelize open-source principles.
While the Open Source Initiative sought to encourage the use of
the new term and evangelize the principles it adhered to, commercial
software vendors found themselves increasingly threatened by the concept
of freely distributed software and universal access to an application's
source code. A Microsoft
executive publicly stated in 2001 that "open source is an intellectual
property destroyer. I can't imagine something that could be worse than
this for the software business and the intellectual-property business." However, while Free and open-source software has historically played a role outside of the mainstream of private software development, companies as large as Microsoft
have begun to develop official open-source presences on the Internet.
IBM, Oracle, Google, and State Farm are just a few of the companies with
a serious public stake in today's competitive open-source market. There
has been a significant shift in the corporate philosophy concerning the
development of FOSS.
The free-software movement
was launched in 1983. In 1998, a group of individuals advocated that
the term free software should be replaced by open-source software (OSS)
as an expression which is less ambiguous and more comfortable for the corporate world. Software developers may want to publish their software with an open-source license,
so that anybody may also develop the same software or understand its
internal functioning. With open-source software, generally, anyone is
allowed to create modifications of it, port it to new operating systems
and instruction set architectures,
share it with others or, in some cases, market it. Scholars Casson and
Ryan have pointed out several policy-based reasons for adoption of open
source – in particular, the heightened value proposition from open
source (when compared to most proprietary formats) in the following
categories:
- Security
- Affordability
- Transparency
- Perpetuity
- Interoperability
- Flexibility
- Localization – particularly in the context of local governments (who make software decisions). Casson and Ryan argue that "governments have an inherent responsibility and fiduciary duty to taxpayers" which includes the careful analysis of these factors when deciding to purchase proprietary software or implement an open-source option.
The Open Source Definition
presents an open-source philosophy and further defines the terms of
use, modification and redistribution of open-source software. Software
licenses grant rights to users which would otherwise be reserved by
copyright law to the copyright holder. Several open-source software
licenses have qualified within the boundaries of the Open Source Definition. The most prominent and popular example is the GNU General Public License
(GPL), which "allows free distribution under the condition that further
developments and applications are put under the same licence", thus
also free.
The open source label came out of a strategy session held on April 7, 1998 in Palo Alto in reaction to Netscape's January 1998 announcement of a source code release for Navigator (as Mozilla). A group of individuals at the session included Tim O'Reilly, Linus Torvalds, Tom Paquin, Jamie Zawinski, Larry Wall, Brian Behlendorf, Sameer Parekh, Eric Allman, Greg Olson, Paul Vixie, John Ousterhout, Guido van Rossum, Philip Zimmermann, John Gilmore and Eric S. Raymond.[17] They used the opportunity before the release of Navigator's source code to clarify a potential confusion caused by the ambiguity of the word "free" in English.
Many people claimed that the birth of the Internet, since 1969, started the open-source movement, while others do not distinguish between open-source and free software movements.
The Free Software Foundation (FSF), started in 1985, intended the word "free" to mean freedom to distribute (or "free as in free speech") and not freedom from cost
(or "free as in free beer"). Since a great deal of free software
already was (and still is) free of charge, such free software became
associated with zero cost, which seemed anti-commercial.
The Open Source Initiative
(OSI) was formed in February 1998 by Eric Raymond and Bruce Perens.
With at least 20 years of evidence from case histories of closed
software development versus open development already provided by the
Internet developer community, the OSI presented the "open source" case
to commercial businesses, like Netscape. The OSI hoped that the use of
the label "open source", a term suggested by Christine Peterson of the Foresight Institute
at the strategy session, would eliminate ambiguity, particularly for
individuals who perceive "free software" as anti-commercial. They sought
to bring a higher profile to the practical benefits of freely available
source code, and they wanted to bring major software businesses and
other high-tech industries into open source. Perens attempted to
register "open source" as a service mark for the OSI, but that attempt was impractical by trademark
standards. Meanwhile, due to the presentation of Raymond's paper to the
upper management at Netscape—Raymond only discovered when he read the press release, and was called by Netscape CEO Jim Barksdale's PA later in the day—Netscape released its Navigator source code as open source, with favorable results.
Definitions
The logo of the Open Source Initiative
The Open Source Initiative's (OSI) definition is recognized by several governments internationally as the standard or de facto
definition. In addition, many of the world's largest
open-source-software projects and contributors, including Debian, Drupal
Association, FreeBSD Foundation, Linux Foundation, OpenSUSE Foundation,
Mozilla Foundation, Wikimedia Foundation, Wordpress Foundation have
committed to upholding the OSI's mission and Open Source Definition through the OSI Affiliate Agreement.
OSI uses The Open Source Definition to determine whether it considers a software license open source. The definition was based on the Debian Free Software Guidelines, written and adapted primarily by Perens. Perens did not base his writing on the "four freedoms" from the Free Software Foundation (FSF), which were only widely available later.
Under Perens' definition, open source is a broad software
license that makes source code available to the general public with
relaxed or non-existent restrictions on the use and modification of the
code. It is an explicit "feature" of open source that it puts very few
restrictions on the use or distribution by any organization or user, in
order to enable the rapid evolution of the software.
Despite initially accepting it, Richard Stallman
of the FSF now flatly opposes the term "Open Source" being applied to
what they refer to as "free software". Although he agrees that the two
terms describe "almost the same category of software", Stallman
considers equating the terms incorrect and misleading. Stallman also opposes the professed pragmatism of the Open Source Initiative,
as he fears that the free software ideals of freedom and community are
threatened by compromising on the FSF's idealistic standards for
software freedom. The FSF considers free software to be a subset of open-source software, and Richard Stallman explained that DRM
software, for example, can be developed as open source, despite that it
does not give its users freedom (it restricts them), and thus doesn't
qualify as free software.
Open-source software licensing
When an author contributes code to an open-source project (e.g.,
Apache.org) they do so under an explicit license (e.g., the Apache
Contributor License Agreement) or an implicit license (e.g. the
open-source license under which the project is already licensing code).
Some open-source projects do not take contributed code under a license,
but actually require joint assignment of the author's copyright in order
to accept code contributions into the project.
Examples of free software license / 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.
The proliferation of open-source licenses
is a negative aspect of the open-source movement because it is often
difficult to understand the legal implications of the differences
between licenses. With more than 180,000 open-source projects available
and more than 1400 unique licenses, the complexity of deciding how to
manage open-source use within "closed-source" commercial enterprises has
dramatically increased. Some are home-grown, while others are modeled
after mainstream FOSS
licenses such as Berkeley Software Distribution ("BSD"), Apache,
MIT-style (Massachusetts Institute of Technology), or GNU General Public
License ("GPL"). In view of this, open-source practitioners are
starting to use classification schemes in which FOSS licenses are grouped (typically based on the existence and obligations imposed by the copyleft provision; the strength of the copyleft provision).
An important legal milestone for the open source / free software
movement was passed in 2008, when the US federal appeals court ruled
that free software licenses
definitely do set legally binding conditions on the use of copyrighted
work, and they are therefore enforceable under existing copyright law.
As a result, if end-users violate the licensing conditions, their
license disappears, meaning they are infringing copyright.
Despite this licensing risk, most commercial software vendors are using
open-source software in commercial products while fulfilling the license
terms, e.g. leveraging the Apache license.
Certifications
Certification
can help to build user confidence. Certification could be applied to
the simplest component, to a whole software system. The United Nations University International Institute for Software Technology,
initiated a project known as "The Global Desktop Project". This project
aims to build a desktop interface that every end-user is able to
understand and interact with, thus crossing the language and cultural
barriers. The project would improve developing nations' access to
information systems. UNU/IIST hopes to achieve this without any
compromise in the quality of the software by introducing certifications.
Open-source software development
Development model
In his 1997 essay The Cathedral and the Bazaar, 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, "carefully crafted by individual
wizards or small bands of mages working in splendid isolation".
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."
In the traditional model of development, which he called 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.
The bazaar model, however, is different. In this model, roles are not clearly defined. Gregorio Robles 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, "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 the 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
- Code changes should be integrated (merged into a shared code base) 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.
- High modularization
- The general structure of the software should be modular allowing for parallel development on independent components.
- 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. Compare with extreme programming.
Data suggests, however, that OSS is not quite as democratic as the
bazaar model suggests. An analysis of five billion bytes of
free/open-source code by 31,999 developers shows that 74% of the code
was written by the most active 10% of authors. The average number of
authors involved in a project was 5.1, with the median at 2.
Advantages and disadvantages
Open-source
software is usually easier to obtain than proprietary software, often
resulting in increased use. Additionally, the availability of an
open-source implementation of a standard can increase adoption of that
standard. It has also helped to build developer loyalty as developers feel empowered and have a sense of ownership of the end product.
Moreover, lower costs of marketing and logistical services are
needed for OSS. It is a good tool to promote a company's image,
including its commercial products. The OSS development approach has helped produce reliable, high quality software quickly and inexpensively.
Open-source development offers the potential for a more flexible
technology and quicker innovation. It is said to be more reliable since
it typically has thousands of independent programmers testing and fixing
bugs of the software. Open source is not dependent on the company or
author that originally created it. Even if the company fails, the code
continues to exist and be developed by its users. Also, it uses open
standards accessible to everyone; thus, it does not have the problem of
incompatible formats that may exist in proprietary software.
It is flexible because modular systems allow programmers to build
custom interfaces, or add new abilities to it and it is innovative
since open-source programs are the product of collaboration among a
large number of different programmers. The mix of divergent
perspectives, corporate objectives, and personal goals speeds up
innovation.
Moreover, free software can be developed in accord with purely
technical requirements. It does not require thinking about commercial
pressure that often degrades the quality of the software. Commercial
pressures make traditional software developers pay more attention to
customers' requirements than to security requirements, since such
features are somewhat invisible to the customer.
It is sometimes said that the open-source development process may
not be well defined and the stages in the development process, such as
system testing and documentation may be ignored. However this is only
true for small (mostly single programmer) projects. Larger, successful
projects do define and enforce at least some rules as they need them to
make the teamwork possible. In the most complex projects these rules may be as strict as reviewing even minor change by two independent developers.
Not all OSS initiatives have been successful, for example SourceXchange and Eazel.
Software experts and researchers who are not convinced by open source's
ability to produce quality systems identify the unclear process, the
late defect discovery and the lack of any empirical evidence as the most
important problems (collected data concerning productivity and
quality).
It is also difficult to design a commercially sound business model
around the open-source paradigm. Consequently, only technical
requirements may be satisfied and not the ones of the market.
In terms of security, open source may allow hackers to know about the
weaknesses or loopholes of the software more easily than closed-source
software. It depends on control mechanisms in order to create effective
performance of autonomous agents who participate in virtual
organizations.
Development tools
In OSS development, tools are used to support the development of the product and the development process itself.
Revision control systems such as Concurrent Versions System (CVS) and later Subversion (SVN) and Git
are examples of tools, often themselves open source, help manage the
source code files and the changes to those files for a software project. The projects are frequently hosted and published on source-code-hosting facilities such as Launchpad.
Open-source projects are often loosely organized with "little
formalised process modelling or support", but utilities such as issue
trackers are often used to organize open-source software development. Commonly used bugtrackers include Bugzilla and Redmine.
Tools such as mailing lists and IRC provide means of coordination among developers. Centralized code hosting sites also have social features that allow developers to communicate.
Organizations
Some of the "more prominent organizations" involved in OSS development include the Apache Software Foundation, creators of the Apache web server; the Linux Foundation, a nonprofit which as of 2012 employed Linus Torvalds, the creator of the Linux operating system kernel; the Eclipse Foundation, home of the Eclipse software development platform; the Debian Project, creators of the influential Debian GNU/Linux distribution; the Mozilla Foundation, home of the Firefox web browser; and OW2,
European-born community developing open-source middleware. New
organizations tend to have a more sophisticated governance model and
their membership is often formed by legal entity members.
Open Source Software Institute
is a membership-based, non-profit (501 (c)(6)) organization established
in 2001 that promotes the development and implementation of open source
software solutions within US Federal, state and local government
agencies. OSSI's efforts have focused on promoting adoption of
open-source software programs and policies within Federal Government and
Defense and Homeland Security communities.
Open Source for America
is a group created to raise awareness in the United States Federal
Government about the benefits of open-source software. Their stated
goals are to encourage the government's use of open source software,
participation in open-source software projects, and incorporation of
open-source community dynamics to increase government transparency.
Mil-OSS is a group dedicated to the advancement of OSS use and creation in the military.
Funding
Companies whose business center on the development of open-source software
employ a variety of business models to solve the challenge of how to
make money providing software that is by definition licensed free of
charge. Each of these business strategies rests on the premise that
users of open-source technologies are willing to purchase additional
software features under proprietary licenses, or purchase other services
or elements of value that complement the open-source software that is
core to the business. This additional value can be, but not limited to,
enterprise-grade features and up-time guarantees (often via a service-level agreement)
to satisfy business or compliance requirements, performance and
efficiency gains by features not yet available in the open source
version, legal protection (e.g., indemnification from copyright or
patent infringement), or professional support/training/consulting that
are typical of proprietary software applications.
Comparisons with other software licensing/development models
Closed source / proprietary software
The debate over open source vs. closed source (alternatively called proprietary software) is sometimes heated.
The top four reasons (as provided by Open Source Business Conference survey) individuals or organizations choose open-source software are:
- lower cost
- security
- no vendor 'lock in'
- better quality
Since innovative companies no longer rely heavily on software sales, proprietary software has become less of a necessity. As such, things like open-source content management system—or CMS—deployments are becoming more commonplace. In 2009, the US White House switched its CMS system from a proprietary system to Drupal open source CMS. Further, companies like Novell
(who traditionally sold software the old-fashioned way) continually
debate the benefits of switching to open-source availability, having
already switched part of the product offering to open source code. In this way, open-source software provides solutions to unique or specific problems. As such, it is reported that 98% of enterprise-level companies use open-source software offerings in some capacity.
With this market shift, more critical systems are beginning to rely on open-source offerings, allowing greater funding (such as US Department of Homeland Security grants)
to help "hunt for security bugs." According to a pilot study of
organizations adopting (or not adopting) OSS, the following factors of
statistical significance were observed in the manager's beliefs: (a)
attitudes toward outcomes, (b) the influences and behaviors of others,
and (c) their ability to act.
Proprietary source distributors have started to develop and
contribute to the open-source community due to the market share shift,
doing so by the need to reinvent their models in order to remain
competitive.
Many advocates argue that open-source software is inherently safer because any person can view, edit, and change code.
A study of the Linux source code has 0.17 bugs per 1000 lines of code
while proprietary software generally scores 20–30 bugs per 1000 lines.
Free software
According to the Free software movement's leader, Richard Stallman, the main difference is that by choosing one term over the other (i.e. either "open source" or "free software")
one lets others know about what one's goals are: "Open source is a
development methodology; free software is a social movement." Nevertheless, there is significant overlap between open source software and free software.
The FSF
said that the term "open source" fosters an ambiguity of a different
kind such that it confuses the mere availability of the source with the
freedom to use, modify, and redistribute it. On the other hand, the
"free software" term was criticized for the ambiguity of the word "free"
as "available at no cost", which was seen as discouraging for business
adoption, and for the historical ambiguous usage of the term.
Developers have used the alternative terms Free and Open Source Software (FOSS), or Free/Libre and Open Source Software (FLOSS), consequently, to describe open-source software that is also free software. While the definition of open source software is very similar to the FSF's free software definition it was based on the Debian Free Software Guidelines, written and adapted primarily by Bruce Perens with input from Eric S. Raymond and others.
The term "open source" was originally intended to be
trademarkable; however, the term was deemed too descriptive, so no
trademark exists.
The OSI would prefer that people treat open source as if it were a
trademark, and use it only to describe software licensed under an OSI
approved license.
OSI Certified is a trademark licensed only to people who
are distributing software licensed under a license listed on the Open
Source Initiative's list.
Open-source versus source-available
Although the OSI definition of "open-source software" is widely
accepted, a small number of people and organizations use the term to
refer to software where the source is available for viewing, but which
may not legally be modified or redistributed. Such software is more
often referred to as source-available, or as shared source, a term coined by Microsoft in 2001. While in 2007 two of Microsoft's Shared Source Initiative licenses were certified by the OSI, most licenses from the SSI program are still source-available only.
Open-sourcing
Open-sourcing is the act of propagating the open source movement, most often referring to releasing previously proprietary software under an open source/free software license, but it may also refer programming Open Source software or installing Open Source software.
Notable software packages, previously proprietary, which have been open sourced include:
- Netscape Navigator, the code of which became the basis of the Mozilla and Mozilla Firefox web browsers
- StarOffice, which became the base of the OpenOffice.org office suite and LibreOffice
- Global File System, was originally GPL'd, then made proprietary in 2001(?), but in 2004 was re-GPL'd.
- SAP DB, which has become MaxDB, and is now distributed (and owned) by MySQL AB
- InterBase database, which was open sourced by Borland in 2000 and presently exists as a commercial product and an open-source fork (Firebird)
Before changing the license of software, distributors usually audit
the source code for third party licensed code which they would have to
remove or obtain permission for its relicense. Backdoors and other malware should also be removed as they may easily be discovered after release of the code.
Current applications and adoption
"We migrated key
functions from Windows to Linux because we needed an operating system
that was stable and reliable – one that would give us in-house control.
So if we needed to patch, adjust, or adapt, we could."
Official statement of the United Space Alliance, which manages the computer systems for the International Space Station (ISS), regarding why they chose to switch from Windows to Debian GNU/Linux on the ISS
Widely used open-source software
Open-source software projects are built and maintained by a network
of volunteer programmers and are widely used in free as well as
commercial products. Prime examples of open-source products are the Apache HTTP Server, the e-commerce platform osCommerce, internet browsers Mozilla Firefox and Chromium (the project where the vast majority of development of the freeware Google Chrome is done) and the full office suite LibreOffice. One of the most successful open-source products is the GNU/Linux operating system, an open-source Unix-like operating system, and its derivative Android, an operating system for mobile devices. In some industries, open-source software is the norm.
Extensions for non-software use
While the term "open source" applied originally only to the source code of software, it is now being applied to many other areas such as Open source ecology,
a movement to decentralize technologies so that any human can use them.
However, it is often misapplied to other areas that have different and
competing principles, which overlap only partially.
The same principles that underlie open-source software can be found in many other ventures, such as open-source hardware, Wikipedia, and open-access publishing. Collectively, these principles are known as open source, open content, and open collaboration:
"any system of innovation or production that relies on goal-oriented
yet loosely coordinated participants, who interact to create a product
(or service) of economic value, which they make available to
contributors and non-contributors alike."
This "culture" or ideology takes the view that the principles
apply more generally to facilitate concurrent input of different
agendas, approaches, and priorities, in contrast with more centralized
models of development such as those typically used in commercial
companies.
