Dual-licensing is the practice of distributing identical software under two different sets of terms and conditions. This may mean two different licenses, or two different sets of licenses. Software is sometimes offered under more than two licenses, in which cases tri-licensing or multi-licensing may be a more accurate term.
When software is dual-licensed, recipients can choose which terms they want to use or distribute the software under. The distributor may or may not apply a fee to either option.
The two usual motivations for dual-licensing are license compatibility and market segregation based business models.
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Business models
This is commonly done to support free software business models. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified In this model, one option is a proprietary software license, which allows the possibility of creating proprietary applications derived from it, while the other license is a copyleft free software/open-source license, thus requiring any derived work to be released under the same license. Proprietary software is Computer software on which the producer has set restrictions on use private modification copying, or republishing. Copyleft is a play on the word Copyright and describes the practice of using copyright law to remove restrictions on distributing copies and modified versions A free software licence is a Software licence which grants recipients rights to modify and redistribute the Software which would otherwise be prohibited by Copyright An open source license is a copyright License for Computer software that makes the source code available under terms that allow for modification and redistribution The copyright holder of the software then typically gives away the free/open source version of the software at no cost, and profits by selling licenses to commercial operations looking to incorporate the software into their own business. This model can be compared to Shareware. The term shareware, popularized by Bob Wallace, refers to Copyrighted commercial Software that is Distributed without payment on a trial [1][2]
Since in most cases only the copyright holder can change the licensing terms of a software, dual licensing is mostly used by companies that wholly own the software which they are licensing.
Dual licensing is used by the copyright holders of some free software packages advertising their willingness to distribute using both a copyleft free software license and a non-free software license. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified Copyleft is a play on the word Copyright and describes the practice of using copyright law to remove restrictions on distributing copies and modified versions The latter license typically offers users the software as proprietary software or offers third parties the source code without copyleft provisions. Proprietary software is Computer software on which the producer has set restrictions on use private modification copying, or republishing. Copyright holders are exercising the monopoly they're provided under copyright in this scenario, but also use dual licensing to discriminate the rights and freedoms different recipients receive. Copyright is a legal concept enacted by Governments, giving the creator of an original work of authorship Exclusive rights to control its distribution usually for
Such licensing allows the holder to offer customisations, early releases, generate other derivative works or grant rights to third parties to redistribute proprietary versions all while offering everyone a free version of the software. Sharing the package as copyleft free software can benefit the copyright holder by receiving contributions from users and hackers of the free software community. The free software community is an informal term referring to the users and developers of Free software as well as supporters of the Free software movement. These contributions can be the support of a dedicated user community, word of mouth marketing or modifications that are made available as stipulated by a copyleft license. Word of mouth, is a reference to the passing of Information by verbal means especially recommendations but also general information in an informal person-to-person However, a copyright holder's commitment to elude copyleft provisions and advertise proprietary redistributions risks losing confidence and support from free software users. [3] [4]
Examples include MySQL AB's database, Gaia Ajax Widgets, and Trolltech's Qt development toolkit. MySQL AB (founded 1995 acquired by Sun Microsystems 2008 was dual headquartered in Uppsala, Sweden and Cupertino, California Qt (pronounced "cute" by its creators is a Cross-platform application development framework widely used for the development of GUI programs (in which
License compatibility
A second use of dual-licensing with free software is for license compatibility, allowing code from differently licensed free software projects to be combined, or to provide users the preference to pick a license.
Examples include the source code of Mozilla Application Suite, Mozilla Thunderbird and Mozilla Firefox, which is tri-licensed under the Mozilla Public License (MPL), GNU General Public License (GPL) and GNU Lesser General Public License (LGPL);[1] and Perl, which is dual-licensed under the GPL and Artistic License. The Mozilla Application Suite (originally known as Mozilla, marketed as the Mozilla Suite, and Code named SeaMonkey) is a Cross-platform Mozilla Thunderbird is a free, Open source, Cross-platform e-mail and News client developed by the Mozilla Foundation. The Mozilla Public License (MPL is a free and Open source Software license. The GNU Lesser General Public License (formerly the GNU Library General Public License) or LGPL is a Free software license published by the Free Software NOTES FOR EDITORS "Perl" is not an acronym (read the "Name" section below Artistic license (also known as dramatic license, poetic license, narrative license, licentia poetica, or simply license) is a colloquial [2]
Market segregation in proprietary software
Dual licensing is also used by some distributors of non-free software. Sometimes this is done to proprietary software to segregate a market. By splitting people into multiple categories such as home users, professional users, and academic users, copyright holders can set different prices for each group. However, among proprietary software, it is more common "home edition" and "professional edition" be also differentiated by the software included, not just the license.
References
- ^ Mozilla Foundation. Mozilla Code Licensing. Retrieved on 2007-09-17. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1176 - The Battle of Myriokephalon is fought 1462 - The Battle of Świecino (or Battle of Żarnowiec
- ^ The Perl Foundation. Perl Licensing - perl.org. Retrieved on 2007-09-17. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1176 - The Battle of Myriokephalon is fought 1462 - The Battle of Świecino (or Battle of Żarnowiec
External links
- Dual Licensing information from OSS Watch
- Article "Does dual licensing threaten free software?" by Glyn Moody
- Article "The Dual-Licensing Model" by Don Marti
- Article "Dual Licensing: Having Your Cake and Eating It Too" by Philip H. OSS Watch is the United Kingdom 's advisory service for issues relating to free and Open source software in the Further Education and Higher Education Albert
- Article "Dual-Licensing Open Source Business Models" by Heather Meeker
- Article "How to use open source as a power marketing tool" by John Koenig
- Paper "Dual Licensing in Open Source Software Industry" by Mikko Välimäki
- Dual Licensing Schemes
- "Should code be “dual licensed” under the GPL and a permissive license?" by Software Freedom Law Center
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