Mozilla Public License
Encyclopedia
The Mozilla Public License (MPL) is a free
and open source
software license. Version 1.0 was developed by Mitchell Baker
when she worked as a lawyer
at Netscape Communications Corporation and version 1.1 at the Mozilla Foundation
. The MPL is characterized as a hybridization of the modified BSD license and GNU General Public License
.
The MPL is the license for the Mozilla Application Suite
, Mozilla Firefox
, Mozilla Thunderbird
and other Mozilla software. The MPL has been adapted by others as a license for their software, most notably Sun Microsystems
, as the Common Development and Distribution License
for OpenSolaris
, the open source version of the Solaris 10 operating system, and by Adobe
, as the license for its Flex
product line.
. Specifically, source code
copied or changed under the MPL must stay under the MPL.
The MPL was approved both as an Open Source software license by the Open Source Initiative
and as a Free Software license
by the Free Software Foundation
.
Much like the GNU General Public License (GPL), NPL required all modifications of original code to be released under NPL as well. However, unlike the GPL, the NPL did not require that new code which interacted with the covered code be licensed under NPL, even if the covered code was modified to work more aptly with the new code. The open source community found this provision in the NPL license allowing Netscape Communications to re-license code contributed by other users to be contrary to the goals of the free software movement.
The MPL was designed to cover new code which interacted with the covered code to be licensed under NPL. This license held even if the covered code was modified to work more aptly with the new code. The MPL does not have the same restrictions as outlined above in the NPL.
The rights granted by the initial author include:
1. to use, reproduce, modify, display, perform, sublicense, and distribute the source, and modified version of the source.
2. patent rights to use and make available the original code
3. to distribute works which contain the code in combination with new code, and to license the new code in any way the distributor wishes
The rights granted by subsequent users include:
1. to use, reproduce, modify, display, perform, sublicense and distribute the source of their modifications
2. patent rights to use and make available both the modifications and the entire work
3. to distribute works which contain the code in combination with new code, and to license the new code in any way the distributor wishes
There are some conditions which are attached to these rights. The most salient conditions are that all distributed copies must contain the source code, all modifications must be described in accompanying documentation, all necessary patents must be described in accompanying documentation, all copies of the code must have a statement of copyright attached, and all modified code must be distributed under MPL, although new files containing new code need not be distributed under MPL. The way in which the Mozilla Public License is drafted basically requires subsequent users to license the original code under MPL and all additional code under any kind of license. Therefore, a company can create a proprietary product from code licensed under MPL by licensing the added components in a closed source manner. The stipulation that core files stay under the MPL provides incentive for developers to improve and develop aspects of the core functionality. The MPL is GPL-incompatible because the GPL module cannot be legally linked with an MPL module. However, versions of the MPL such as MPL 1.1 have a provision that allows part of a program to offer the GNU GPL as an alternative choice, thereby allowing part of the program to have a GPL-compatible license.
files in one program ("Larger Work"). For example, Netscape
6 and later releases were proprietary versions of the Mozilla Application Suite, by adding the proprietary AIM and other parts. The MPL treats the source code file as the boundary between MPL code and proprietary parts, meaning that a certain source file (e.g., C++, JavaScript or XUL file) is either fully MPL or fully proprietary. The GPL, in contrast, uses the process boundary of the executable as the license boundary (for details, see GPL).
(FSF) considers the license a free software license, albeit one with a weak copyleft. However, "unlike the X11 license" (MIT License
) the license has "some complex restrictions" making it incompatible
with the GNU GPL. They urge people not to use the license because of this incompatibility unless the provision in section 13 of the MPL is exercised to provide the work under either the GPL or any other GPL-compatible license.
For these reasons, the Mozilla Suite and Firefox have been relicensed under multiple licenses
, including the MPL, GPL and LGPL.
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
and open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
software license. Version 1.0 was developed by Mitchell Baker
Mitchell Baker
Winifred Mitchell Baker, better known simply as Mitchell Baker is the Chairperson of the Mozilla Foundation and Chairperson and former Chief Executive Officer of the Mozilla Corporation, a subsidiary of the Mozilla Foundation that coordinates development of the open source Mozilla Internet...
when she worked as a lawyer
Lawyer
A lawyer, according to Black's Law Dictionary, is "a person learned in the law; as an attorney, counsel or solicitor; a person who is practicing law." Law is the system of rules of conduct established by the sovereign government of a society to correct wrongs, maintain the stability of political...
at Netscape Communications Corporation and version 1.1 at the Mozilla Foundation
Mozilla Foundation
The Mozilla Foundation is a non-profit organization that exists to support and provide leadership for the open source Mozilla project. The organization sets the policies that govern development, operates key infrastructure and controls trademarks and other intellectual property...
. The MPL is characterized as a hybridization of the modified BSD license and GNU General Public License
GNU General Public License
The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....
.
The MPL is the license for the Mozilla Application Suite
Mozilla Application Suite
The Mozilla Application Suite is a cross-platform integrated Internet suite. Its development was initiated by Netscape Communications Corporation, before their acquisition by AOL. It is based on the source code of Netscape Communicator...
, Mozilla Firefox
Mozilla Firefox
Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. , Firefox is the second most widely used browser, with approximately 25% of worldwide usage share of web browsers...
, Mozilla Thunderbird
Mozilla Thunderbird
Mozilla Thunderbird is a free, open source, cross-platform e-mail and news client developed by the Mozilla Foundation. The project strategy is modeled after Mozilla Firefox, a project aimed at creating a web browser...
and other Mozilla software. The MPL has been adapted by others as a license for their software, most notably Sun Microsystems
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
, as the Common Development and Distribution License
Common Development and Distribution License
Common Development and Distribution License is a free software license, produced by Sun Microsystems, based on the Mozilla Public License , version 1.1....
for OpenSolaris
OpenSolaris
OpenSolaris was an open source computer operating system based on Solaris created by Sun Microsystems. It was also the name of the project initiated by Sun to build a developer and user community around the software...
, the open source version of the Solaris 10 operating system, and by Adobe
Adobe Systems
Adobe Systems Incorporated is an American computer software company founded in 1982 and headquartered in San Jose, California, United States...
, as the license for its Flex
Adobe Flex
Adobe Flex is a software development kit released by Adobe Systems for the development and deployment of cross-platform rich Internet applications based on the Adobe Flash platform...
product line.
Terms
The license is regarded as a weak copyleftCopyleft
Copyleft is a play on the word copyright to describe the practice of using copyright law to offer the right to distribute copies and modified versions of a work and requiring that the same rights be preserved in modified versions of the work...
. Specifically, source code
Source code
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
copied or changed under the MPL must stay under the MPL.
The MPL was approved both as an Open Source software license by the Open Source Initiative
Open Source Initiative
The Open Source Initiative is an organization dedicated to promoting open source software.The organization was founded in February 1998, by Bruce Perens and Eric S. Raymond, prompted by Netscape Communications Corporation publishing the source code for its flagship Netscape Communicator product...
and as a Free Software license
Free software licence
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 law. A free software licence grants, to the recipients, freedoms in the form of permissions to modify or distribute copyrighted work...
by the Free Software Foundation
Free Software Foundation
The Free Software Foundation is a non-profit corporation founded by Richard Stallman on 4 October 1985 to support the free software movement, a copyleft-based movement which aims to promote the universal freedom to create, distribute and modify computer software...
.
History of Mozilla Public License
The Mozilla Public License (MPL) was drafted by the software company Netscape Communications in 1998 in conjunction with the Netscape Public License (NPL). The NPL was created as a means for Netscape Communications to license the source code for their browser Netscape Communicator while maintaining a certain degree of proprietary rights. They required a license that protected their source code in a manner that allowed the company to take modifications to the code made by open source developers and use that code in commercial products. That also allowed other commercial companies to build their own browsers on top of the Netscape codebase.Much like the GNU General Public License (GPL), NPL required all modifications of original code to be released under NPL as well. However, unlike the GPL, the NPL did not require that new code which interacted with the covered code be licensed under NPL, even if the covered code was modified to work more aptly with the new code. The open source community found this provision in the NPL license allowing Netscape Communications to re-license code contributed by other users to be contrary to the goals of the free software movement.
The MPL was designed to cover new code which interacted with the covered code to be licensed under NPL. This license held even if the covered code was modified to work more aptly with the new code. The MPL does not have the same restrictions as outlined above in the NPL.
Features of the MPL
The Mozilla Public License divides the rights it grants into two sections: the rights granted by the code's initial author and the rights granted by other people who have added sections of code to the original author's work.The rights granted by the initial author include:
1. to use, reproduce, modify, display, perform, sublicense, and distribute the source, and modified version of the source.
2. patent rights to use and make available the original code
3. to distribute works which contain the code in combination with new code, and to license the new code in any way the distributor wishes
The rights granted by subsequent users include:
1. to use, reproduce, modify, display, perform, sublicense and distribute the source of their modifications
2. patent rights to use and make available both the modifications and the entire work
3. to distribute works which contain the code in combination with new code, and to license the new code in any way the distributor wishes
There are some conditions which are attached to these rights. The most salient conditions are that all distributed copies must contain the source code, all modifications must be described in accompanying documentation, all necessary patents must be described in accompanying documentation, all copies of the code must have a statement of copyright attached, and all modified code must be distributed under MPL, although new files containing new code need not be distributed under MPL. The way in which the Mozilla Public License is drafted basically requires subsequent users to license the original code under MPL and all additional code under any kind of license. Therefore, a company can create a proprietary product from code licensed under MPL by licensing the added components in a closed source manner. The stipulation that core files stay under the MPL provides incentive for developers to improve and develop aspects of the core functionality. The MPL is GPL-incompatible because the GPL module cannot be legally linked with an MPL module. However, versions of the MPL such as MPL 1.1 have a provision that allows part of a program to offer the GNU GPL as an alternative choice, thereby allowing part of the program to have a GPL-compatible license.
Compatibility with other licenses
Unlike strong copyleft licenses, the code under the MPL may be combined with proprietaryProprietary software
Proprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.Complementary...
files in one program ("Larger Work"). For example, Netscape
Netscape (web browser)
Netscape 7 was a series of proprietary cross-platform Internet suites created by Netscape Communications Corporation and then in-house by AOL to continue the Netscape series after Netscape 6. There were three main editions released from the Netscape 7 series; being Netscape 7.0, 7.1 and 7.2...
6 and later releases were proprietary versions of the Mozilla Application Suite, by adding the proprietary AIM and other parts. The MPL treats the source code file as the boundary between MPL code and proprietary parts, meaning that a certain source file (e.g., C++, JavaScript or XUL file) is either fully MPL or fully proprietary. The GPL, in contrast, uses the process boundary of the executable as the license boundary (for details, see GPL).
Compatibility with GPL
The Free Software FoundationFree Software Foundation
The Free Software Foundation is a non-profit corporation founded by Richard Stallman on 4 October 1985 to support the free software movement, a copyleft-based movement which aims to promote the universal freedom to create, distribute and modify computer software...
(FSF) considers the license a free software license, albeit one with a weak copyleft. However, "unlike the X11 license" (MIT License
MIT License
The MIT License is a free software license originating at the Massachusetts Institute of Technology . It is a permissive license, meaning that it permits reuse within proprietary software provided all copies of the licensed software include a copy of the MIT License terms...
) the license has "some complex restrictions" making it incompatible
License compatibility
License compatibility refers to the problem with licenses applied to works subject to copyright, particularly licenses of software packages, which can contain contradictory requirements, rendering it impossible to combine source code from such packages or content from such works in order to create...
with the GNU GPL. They urge people not to use the license because of this incompatibility unless the provision in section 13 of the MPL is exercised to provide the work under either the GPL or any other GPL-compatible license.
For these reasons, the Mozilla Suite and Firefox have been relicensed under multiple licenses
Dual license
Multi-licensing is the practice of distributing software under two or more different sets of terms and conditions. This may mean multiple different licenses or sets of licenses. Prefixes may be used to indicate the number of licenses used, e.g...
, including the MPL, GPL and LGPL.
MPL-based licenses
- AROSArosAros may refer to:*Aros , a river in J. R. R. Tolkien's Middle-earth legendarium*AROS Research Operating System, a free software implementation of AmigaOS* Aros, the original Viking name of Aarhus, the second largest city in Denmark...
Public License - CeltxCeltxCeltx is free media pre-production software designed for creating and organizing media projects like screenplays, films, videos, stageplays, audio plays, documentaries, machinima, comics, games and podcasts....
Public License - Common Development and Distribution LicenseCommon Development and Distribution LicenseCommon Development and Distribution License is a free software license, produced by Sun Microsystems, based on the Mozilla Public License , version 1.1....
- Common Public Attribution LicenseCommon Public Attribution LicenseThe Common Public Attribution License is a free software license approved by the Open Source Initiative in 2007. Its purpose is to be a general license for software distributed over a network...
- Erlang Public License (based on Mozilla Public License v1.0)
- gSOAP Public License
- OpenMRSOpenMRSis a collaborative open source project to develop excellent software to support the delivery of health care in developing countries. It grew out of the critical need to scale up the treatment of HIV in Africa but from the start was conceived as a general purpose electronic medical record system...
Public License - SugarCRMSugarCRMSugarCRM is a software company based in Cupertino, California. They produce the web application Sugar, also known as SugarCRM, which is a customer relationship management system that is available in both open source and Commercial open source applications.Sugar's functionality includes sales-force...
Public License - Sun Public LicenseSun Public LicenseThe Sun Public License is a software license that applies to some open-source software released by Sun Microsystems . It has been approved by the Free Software Foundation as a free software license, and by the Open Source Initiative as an open source license...
- Yahoo! Public LicenseYahoo! Public LicenseYahoo! Public License is a free software license by Yahoo!. It is used among others by old versions of the collaborative software Zimbra. It is approved by the Free Software Foundation as a free software license....
External links
- Mozilla Public License, version 1.1, plain text (mozilla.org)
- Annotated Mozilla Public License, version 1.1 (mozilla.org)
- MPL FAQ (mozilla.org)
- Mozilla Relicensing FAQ (mozilla.org)
- List of OSI approved licenses
- http://www.oss-watch.ac.uk/resources/mpl.xml