Q Public License
Encyclopedia
The Q Public License is a non-copyleft
license, created by Trolltech
for its free
edition of the Qt. It was used until Qt 3.0, as Trolltech toolkit version 4.0 was released under GPL version 2. It fails the Debian Free Software Guidelines
, used by several Linux
distributions, though it qualifies for the Free Software Foundation's Free Software Definition; however, it is not compatible with the FSF's GNU General Public License
, meaning that you cannot legally distribute products derived from both GPL'ed and QPL'ed code.
and authors of the GPL sum up their objections to the QPL:
It also allowed Qt to change the license in later editions of its software, something often also provided in the GPL, and it was also frowned upon that non-free use or development of derivatives was still not allowed. Only the personal edition of Qt was covered by the QPL; the commercial edition, which is functionally equal, is under a pay-per-use license and could not be freely distributed. As KDE
, a desktop environment
for Linux
based on Qt, grew in popularity, the free software community
urged Trolltech to put Qt under a license (the QPL) that would assure that it would remain free software forever and could be used and developed by commercial third-parties. Eventually, under pressure, Trolltech dual-licensed Qt for use under the terms of the GPL or the QPL.
All legal disputes about the license are settled in Oslo
, Norway
, but it has never been legally contested.
The Debian
project rejects software covered by solely QPL (and not dual licensed with something else like the GPL) because of:
Copyleft
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...
license, created by Trolltech
Trolltech
Qt Development Frameworks is an Oslo, Norway-based software company best known for its Qt toolkit and application framework. Qt Development Frameworks is a wholly owned subsidiary of Nokia Corporation...
for its free
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...
edition of the Qt. It was used until Qt 3.0, as Trolltech toolkit version 4.0 was released under GPL version 2. It fails the Debian Free Software Guidelines
Debian Free Software Guidelines
The Debian Free Software Guidelines is a set of guidelines that the Debian Project uses to determine whether a software license is a free software license, which in turn is used to determine whether a piece of software can be included in Debian...
, used by several Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
distributions, though it qualifies for the Free Software Foundation's Free Software Definition; however, it is not compatible with the FSF's 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....
, meaning that you cannot legally distribute products derived from both GPL'ed and QPL'ed code.
Opposition to the license
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...
and authors of the GPL sum up their objections to the QPL:
- This is a non-copyleft free software license which is incompatible with the GNU GPL. It also causes major practical inconvenience, because modified sources can only be distributed as patches.
- We recommend that you avoid using the QPL for anything that you write, and use QPL-covered software packages only when absolutely necessary. However, this avoidance no longer applies to Qt itself, since Qt is now also released under the GNU GPL.
- Since the QPL is incompatible with the GNU GPL, you cannot take a GPL-covered program and QPL-covered program and link them together, no matter how.
- However, if you have written a program that uses QPL-covered library (called FOO), and you want to release your program under the GNU GPL, you can easily do that. You can resolve the conflict for your program by adding a notice like this to it:
-
- As a special exception, you have permission to link this program
- with the FOO library and distribute executables, as long as you
- follow the requirements of the GNU GPL in regard to all of the
- software in the executable aside from FOO.
- You can do this, legally, if you are the copyright holder for the program. Add it in the source files, after the notice that says the program is covered by the GNU GPL.
It also allowed Qt to change the license in later editions of its software, something often also provided in the GPL, and it was also frowned upon that non-free use or development of derivatives was still not allowed. Only the personal edition of Qt was covered by the QPL; the commercial edition, which is functionally equal, is under a pay-per-use license and could not be freely distributed. As KDE
KDE
KDE is an international free software community producing an integrated set of cross-platform applications designed to run on Linux, FreeBSD, Microsoft Windows, Solaris and Mac OS X systems...
, a desktop environment
Desktop environment
In graphical computing, a desktop environment commonly refers to a style of graphical user interface derived from the desktop metaphor that is seen on most modern personal computers. These GUIs help the user in easily accessing, configuring, and modifying many important and frequently accessed...
for Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
based on Qt, grew in popularity, the free software community
Free software community
The free-software community is an informal term that refers to the users and developers of free software as well as supporters of the free-software movement. The movement is sometimes referred to as the open-source software community or a subset thereof...
urged Trolltech to put Qt under a license (the QPL) that would assure that it would remain free software forever and could be used and developed by commercial third-parties. Eventually, under pressure, Trolltech dual-licensed Qt for use under the terms of the GPL or the QPL.
All legal disputes about the license are settled in Oslo
Oslo
Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King...
, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, but it has never been legally contested.
The Debian
Debian
Debian is a computer operating system composed of software packages released as free and open source software primarily under the GNU General Public License along with other free software licenses. Debian GNU/Linux, which includes the GNU OS tools and Linux kernel, is a popular and influential...
project rejects software covered by solely QPL (and not dual licensed with something else like the GPL) because of:
- a choice of venueForum selection clauseA forum selection clause in a contract with a conflict of laws element allows the parties to agree that any litigation resulting from that contract will be initiated in a specific forum...
clause - forced distribution to a third party
- forced blanket license to the original developer
Adoption of the license
Other projects that have adopted the Q Public License, sometimes with a change in the choice of jurisdiction clause, include:- The OCaml compiler and related tools from Projet Cristal at INRIA
- LibreSourceLibreSourceLibreSource is a collaborative development platform for open-source software, groupware, community interaction, electronic archiving and Web publishing....
is a versatile collaborative platform provided by artenum and dedicated to collaborative software development - Jpgraph is a graph generation tool written in PHP that dynamically produces charts and graphs as image files for presentation on websites.
- HerculesHercules emulatorHercules is a computer emulator which allows software designed for IBM mainframe computers and for plug-compatible mainframes to run on other types of computer hardware: notably on low-cost personal computers...
, a software implementation of the System/370System/370The IBM System/370 was a model range of IBM mainframes announced on June 30, 1970 as the successors to the System/360 family. The series maintained backward compatibility with the S/360, allowing an easy migration path for customers; this, plus improved performance, were the dominant themes of the...
, ESA/390ESA/390ESA/390 was introduced in September 1990 and is IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors...
, and z/ArchitectureZ/Architecturez/Architecture, initially and briefly called ESA Modal Extensions , refers to IBM's 64-bit computing architecture for IBM mainframe computers. IBM introduced its first z/Architecture-based system, the zSeries Model 900, in late 2000. Later z/Architecture systems include the IBM z800, z990, z890,...
mainframe computer architectures. - CGALCGALThe Computational Geometry Algorithms Library is a software library that aims to provide easy access to efficient and reliable algorithms in computational geometry. While primarily written in C++, Python and Scilab bindings are also available....