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A source-available software source code distribution model, also called a shared source model, includes arrangements where the source can be viewed, and in some cases modified, but without necessarily meeting the criteria to be called open source. The licenses associated with the offerings range from allowing code to be viewed for reference, to allowing code to be modified and redistributed for both commercial and non-commercial purposes.
- 1 Origin
- 2 Distinction from free software and open-source software
- 3 Criticism
- 4 Free and open-source licenses
- 5 Restricted licenses
- 6 See also
- 7 References
- 8 External links
The term shared source was coined as part of Microsoft's Shared Source Initiative, which was launched in May 2001. The program includes a spectrum of technologies and licenses, and most of its source code offerings are available for download after eligibility criteria are met.
Microsoft's Shared Source Initiative allows individuals and organizations to access Microsoft's source code for reference (e.g. when developing complementary systems), for review and auditing from a security perspective (mostly wanted by some large corporations and governments), and for development (academic institutions, OEMs, individual developers).
As part of the framework, Microsoft released 5 licenses for general use. Two of them, Microsoft Public License and Microsoft Reciprocal License, have been approved by the Open Source Initiative as open source licenses and are regarded by the Free Software Foundation as free software licenses. Other shared source licenses are proprietary, and thus allow the copyright holder to retain tighter control over the use of their product.
Distinction from free software and open-source software
Any software is source available software as long its source code is distributed along with it, even if the user has no legal rights to use, share, modify or even compile it. It is possible for a software to be both source available software and proprietary software, usually because the publisher, developers or another person retains copyright on the software.
In contrast, the definitions of free software and open-source software are much narrower. Free software and/or open-source software is also always source available software, but not all source available software is also free software and/or open-source software. This is because the official definitions of those terms require the software to have their source code available in some form.
Two specific shared source licenses are interpreted as free software and open source licenses by FSF and OSI. However, former OSI president Michael Tiemann considers the phrase "Shared Source" itself to be a marketing term created by Microsoft. He argues that it is "an insurgent term that distracts and dilutes the Open Source message by using similar-sounding terms and offering similar-sounding promises".
Free and open-source licenses
Microsoft Public License (Ms-PL)
This is the least restrictive of the Microsoft licenses and allows for distribution of compiled code for either commercial or non-commercial purposes under any license that complies with the Ms-PL. Redistribution of the source code itself is permitted only under the Ms-PL. Initially titled Microsoft Permissive License, it was renamed to Microsoft Public License while being reviewed for approval by the Open Source Initiative (OSI). The license was approved on October 12, 2007, along with the Ms-RL. According to the Free Software Foundation, it is a free software license but not compatible with the GNU GPL.
Microsoft Reciprocal License (Ms-RL)
This Microsoft license allows for distribution of derived code so long as the modified source files are included and retain the Ms-RL. The Ms-RL allows those files in the distribution that do not contain code originally licensed under Ms-RL to be licensed according to the copyright holder's choosing. This is similar, but not the same as the CDDL, EPL or LGPL (GPL with a typical "linking exception"). Initially known as the Microsoft Community License, it was renamed during the OSI approval process.
On December 9, 2005, the Ms-RL license was submitted to the Open Source Initiative for approval by John Cowan. OSI then contacted Microsoft and asked if they wanted OSI to proceed. Microsoft replied that they did not wish to be reactive and that they needed time to review such a decision.
At the O'Reilly Open Source Convention in July 2007, Bill Hilf, director of Microsoft's work with open source projects, announced that Microsoft had formally submitted Ms-PL and Ms-RL to OSI for approval. It was approved on October 12, 2007, along with the Ms-PL. According to the Free Software Foundation, it is a free software license but not compatible with the GNU GPL.
GitLab Enterprise Edition License (EE License)
GitLab Inc. openly discloses that the EE License makes their Enterprise Edition product "proprietary, closed source code." However, the company makes the source code of the Enterprise Edition public, as well as the repository's issue tracker, and allows users to modify the source code. The dual release of the closed-source Enterprise Edition and the open-source Community Edition makes GitLab an open core company.
Microsoft Limited Public License (Ms-LPL)
This is a version of the Microsoft Public License in which rights are only granted to developers of Microsoft Windows-based software. This license is not open source, as defined by the OSI, because the restriction limiting use of the software to Windows violates the stipulation that open-source licenses must be technology-neutral. It is also considered to be non-free by the Free Software Foundation due to this restriction.
Microsoft Limited Reciprocal License (Ms-LRL)
This is a version of the Microsoft Reciprocal License in which rights are only granted when developing software for a Microsoft Windows platform. Like the Ms-LPL, this license is not open source because it is not technology-neutral due to its restriction that licensed software must be used on Windows, and is also not considered free by the Free Software Foundation due to this restriction.
Microsoft Reference Source License (Ms-RSL)
This is the most restrictive of the Microsoft Shared Source licenses. The source code is made available to view for reference purposes only, mainly to be able to view Microsoft classes source code while debugging. Developers may not distribute or modify the code for commercial or non-commercial purposes. The license has previously been abbreviated Ms-RL, but Ms-RL now refers to the Microsoft Reciprocal License.
SugarCRM Public License
In 2007 Michael Tiemann, president of OSI, had criticized companies such as SugarCRM for promoting their software as "open source" when in fact it did not have an OSI-approved license. In SugarCRM's case, it was because the software is so-called "badgeware" since it specified a "badge" that must be displayed in the user interface (SugarCRM has since switched to GPLv3).
The TrueCrypt License was used by the TrueCrypt disk encryption utility. When TrueCrypt was discontinued, the VeraCrypt fork switched to the Apache License, but retained the TrueCrypt License for code inherited from TrueCrypt.
The Open Source Initiative rejects the TrueCrypt License, as "it has elements incompatible with the OSD." The Free Software Foundation criticizes the license for restricting who can execute the program, and for enforcing a trademark condition.
- "DoD Open Source Software (OSS) FAQ". Chief Information Officer. U.S. Department of Defense. Retrieved 23 Jul 2018.
- Geekzone: Microsoft announces expansion of Shared Source Initiative
- "Various Licenses and Comments about Them". GNU Operating System. Free Software Foundation. Retrieved 23 Jul 2018.
- RISC OS Open
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- Michael Tiemann (2007-11-11). "Who Is Behind "Shared Source" Misinformation Campaign?". Retrieved 2011-03-12.
Shared source is a marketing term created and controlled by Microsoft. Shared source is not open source by another name. Shared source is an insurgent term that distracts and dilutes the Open Source message by using similar-sounding terms and offering similar-sounding promises. And to date, 'shared source' has been a marketing dud as far as Open Source is concerned.
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Acting on the advice of the License Approval Chair, the OSI Board today approved the Microsoft Public License (Ms-PL) and the Microsoft Reciprocal License (Ms-RL). The decision to approve was informed by the overwhelming (though not unanimous) consensus from the open source community that these licenses satisfied the 10 criteria of the Open Source definition, and should therefore be approved.
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- "The GitLab Enterprise Edition (EE) license (the "EE License")". GitLab. GitLab Inc. 16 May 2018. Retrieved 23 Jul 2018.
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- "Microsoft Reference Source License". Microsoft. 2016-07-06. Retrieved 2016-07-06.
"Reference use" means use of the software within your company as a reference, in read only form, for the sole purposes of debugging your products, maintaining your products, or enhancing the interoperability of your products with the software, and specifically excludes the right to distribute the software outside of your company.
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- Vance, Ashlee (2007-07-25). "SugarCRM trades badgeware for GPL 3". The Register. Retrieved 2008-09-08.
- "truecrypt-archive/License-v3.1.txt at master · DrWhax/truecrypt-archive". GitHub. 28 Mar 2014. Retrieved 23 Jul 2018.
- "root/License.txt". VeraCrypt. TrueCrypt Foundation. 17 Oct 2016. Retrieved 23 Jul 2018.
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