The Shared Source Initiative (SSI) is a
source-available
Source-available software is software released through a source code distribution model that includes arrangements where the source can be viewed, and in some cases modified, but without necessarily meeting the criteria to be called open-source ...
software licensing
A software license is a legal instrument (usually by way of contract law, with or without printed material) governing the use or redistribution of software. Under United States copyright law, all software is copyright protected, in both source c ...
scheme launched by
Microsoft
Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washin ...
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.
Overview
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
The Open Source Initiative (OSI) is the steward of the Open Source Definition, the set of rules that define open source software. It is a California public-benefit nonprofit corporation,_with_501(c)(3).html" ;"title="110. - 6910./ref> is a type o ...
as
open source license
An open-source license is a type of license for computer software and other products that allows the source code, blueprint or design to be used, modified and/or shared under defined terms and conditions. This allows end users and commercial compa ...
s and are regarded by the
Free Software Foundation
The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, with the organization's preference for software being distributed under copyleft (" ...
as
free software
Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, no ...
licenses.
Other shared source licenses are proprietary, and thus allow the copyright holder to retain tighter control over the use of their product.
Microsoft's Shared Source Initiative has been imitated by other companies such as
RISC OS Open Ltd
RISC OS Open Ltd. (also referred to as ROOL) is a limited company engaged in computer software and IT consulting. It is managing the process of publishing the source code to RISC OS. Company founders include staff who formerly worked for Pace ...
.
Microsoft also uses specific licenses for some of their products, such as the
Shared Source CLI License and the Microsoft
Windows Embedded CE 6.0 Shared Source License.
Free and open-source licenses
The following licenses are considered
open-source by the
Open Source Initiative
The Open Source Initiative (OSI) is the steward of the Open Source Definition, the set of rules that define open source software. It is a California public-benefit nonprofit corporation,_with_501(c)(3).html" ;"title="110. - 6910./ref> is a type o ...
and
free by the
Free Software Foundation
The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, with the organization's preference for software being distributed under copyleft (" ...
.
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
The Open Source Initiative (OSI) is the steward of the Open Source Definition, the set of rules that define open source software. It is a California public-benefit nonprofit corporation,_with_501(c)(3).html" ;"title="110. - 6910./ref> is a type o ...
(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.
Ms-PL provides a free and flexible licensing for developers using source codes under this license. However, the Ms-PL is a
copyleft
Copyleft is the legal technique of granting certain freedoms over copies of copyrighted works with the requirement that the same rights be preserved in derivative works. In this sense, ''freedoms'' refers to the use of the work for any purpose ...
license because it requires the source code of software it governs to be distributed only under the same license (the Ms-PL).
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
The Common Development and Distribution License (CDDL) is a free and open-source software license, produced by Sun Microsystems, based on the Mozilla Public License (MPL). Files licensed under the CDDL can be combined with files licensed under o ...
,
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
The Open Source Initiative (OSI) is the steward of the Open Source Definition, the set of rules that define open source software. It is a California public-benefit nonprofit corporation,_with_501(c)(3).html" ;"title="110. - 6910./ref> is a type o ...
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
The O'Reilly Open Source Convention (OSCON) was an American annual convention for the discussion of free and open-source software. It was organized by publisher O'Reilly Media and was held each summer, mostly in Portland, Oregon, from 1999 ...
in July 2007,
Bill Hilf
Bill Hilf is the Chief Executive Officer (CEO) of Vulcan Inc. He was appointed CEO on 2 December 2016, succeeding Paul Allen. Before becoming CEO of Vulcan Inc., he was the Senior Vice President and General Manager at Hewlett-Packard Enterprise's ...
, director of Microsoft's work with open source projects, announced that Microsoft had formally submitted Ms-PL and Ms-RL to
OSI
OSI may refer to:
Places
* Osijek Airport (IATA code: OSI), an airport in Croatia
* Ősi, a village in Veszprém county, Hungary
* Oši, an archaeological site in Semigallia, Latvia
* Osi, a village in Ido-Osi, Ekiti State, Nigeria
* Osi, Ekiti ...
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.
Restricted licenses
The following
source-available software
Source-available software is software released through a source code distribution model that includes arrangements where the source can be viewed, and in some cases modified, but without necessarily meeting the criteria to be called open-source ...
licenses have limitations that prevent them from being
open-source according to the
Open Source Initiative
The Open Source Initiative (OSI) is the steward of the Open Source Definition, the set of rules that define open source software. It is a California public-benefit nonprofit corporation,_with_501(c)(3).html" ;"title="110. - 6910./ref> is a type o ...
and
free to the
Free Software Foundation
The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, with the organization's preference for software being distributed under copyleft (" ...
.
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
OSI may refer to:
Places
* Osijek Airport (IATA code: OSI), an airport in Croatia
* Ősi, a village in Veszprém county, Hungary
* Oši, an archaeological site in Semigallia, Latvia
* Osi, a village in Ido-Osi, Ekiti State, Nigeria
* Osi, Ekiti ...
, 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''.
Criticism
Two specific shared source licenses are interpreted as free software and open source licenses by
FSF and
OSI
OSI may refer to:
Places
* Osijek Airport (IATA code: OSI), an airport in Croatia
* Ősi, a village in Veszprém county, Hungary
* Oši, an archaeological site in Semigallia, Latvia
* Osi, a village in Ido-Osi, Ekiti State, Nigeria
* Osi, Ekiti ...
. However, former OSI president
Michael Tiemann
Michael Tiemann is an American software developer and executive, serving as vice president of open source affairs at Red Hat, Inc., and former President of the Open Source Initiative.
Biography
He earned a bachelor's degree from the Moore Scho ...
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".
The Shared Source Initiative has also been noted to increase the problem of
license proliferation
License proliferation is the phenomenon of an abundance of already existing and the continued creation of new software licenses for software and software packages in the FOSS ecosystem. License proliferation affects the whole FOSS ecosystem neg ...
.
Evaluating Microsoft’s Shared Source licenses
Ars Technica, 2007
See also
* Open Source Initiative
The Open Source Initiative (OSI) is the steward of the Open Source Definition, the set of rules that define open source software. It is a California public-benefit nonprofit corporation,_with_501(c)(3).html" ;"title="110. - 6910./ref> is a type o ...
* Source-available software
Source-available software is software released through a source code distribution model that includes arrangements where the source can be viewed, and in some cases modified, but without necessarily meeting the criteria to be called open-source ...
* Software using the Microsoft Public License (category)
References
External links
*
{{FOSS
Microsoft initiatives
Software licenses