On Thu, Jul 22, 2010 at 8:57 PM, Andrew Fitzgerald <andrewfitz.swiftlytilt...@gmail.com> wrote: > Saw an article mentioned on Slashdot about Wordpress themes and plugins > being required to be disributed under the GPL because they are derivative of > Wordpress. Is this also true for Mediawiki extensions and skins? It seems > like the arguements for why Wordpress themes and plugins also apply to MW.
The FSF's position on the issue is that plugins, extensions, and things like that, which link to/call code from a GPL program, must themselves be licensed GPL-compatibly: """ If a program released under the GPL uses plug-ins, what are the requirements for the licenses of a plug-in? It depends on how the program invokes its plug-ins. If the program uses fork and exec to invoke plug-ins, then the plug-ins are separate programs, so the license for the main program makes no requirements for them. If the program dynamically links plug-ins, and they make function calls to each other and share data structures, we believe they form a single program, which must be treated as an extension of both the main program and the plug-ins. This means the plug-ins must be released under the GPL or a GPL-compatible free software license, and that the terms of the GPL must be followed when those plug-ins are distributed. If the program dynamically links plug-ins, but the communication between them is limited to invoking the ‘main’ function of the plug-in with some options and waiting for it to return, that is a borderline case. """ http://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins This is C-oriented, but the application to MediaWiki is fairly clear. Extensions will invariably make function calls back and forth to core code, and share data structures (= objects). This conventional understanding is reflected in MediaWiki's README file, which has stated that extensions must be GPL (citing the above FAQ) for over four years <http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/README?r1=11468&r2=11770>: """ Derivative works and later versions of the code must be free software licensed under the same or a compatible license. This includes "extensions" that use MediaWiki functions or variables; see http://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins for details. """ http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/README?view=markup However, we don't actually enforce this against extensions, even ones hosted on mediawiki.org. (I'd be in favor, but most developers seem to be against.) Another question is JavaScript: stuff that people put in Common.js or whatnot is probably a derivative work by the FSF's standard, but on Wikipedia it's licensed as CC-BY-SA 3.0, which is not GPL-compatible. None of this has actually been tested in court, as far as I know. On Thu, Jul 22, 2010 at 9:19 PM, Q <overlo...@gmail.com> wrote: > So, IMO, generally no in the case of extensions, and depends on the case > of skins. People probably forget that the GPL doesn't dictate what are > classified as derivitive works. No, United States copyright law does. The FSF's lawyers believe that if an extension or plug-in is written that integrates with an existing code base as is designed for that purpose, then it would typically be a derivative work under United States law. Note that the GPLv3 doesn't use the term "derivative work", and instead defines its own term, "modify": """ To “modify” a work means to copy from or adapt all or part of the work in a fashion requiring copyright permission, other than the making of an exact copy. The resulting work is called a “modified version” of the earlier work or a work “based on” the earlier work. """ http://www.gnu.org/licenses/gpl-3.0.html This more explicitly ties the question to local copyright law. The FSF believes that under United States law, the copyright holder for a computer program has the exclusive right to produce new code that is designed to link to the computer program, and thus the GPL restricts that. I'm not aware of any organizations whose lawyers have explicitly disputed this. > So strictly speaking by their own definition, shouldn't WordPress be > licensed under the PHP license? No, because the PHP license is permissive, not copyleft. If the PHP license required that all derivative works be released under it, then it might be required, yes. (However, this case is possibly fuzzier because independent reimplementations like Hiphop are possible based on the public documentation for PHP. Similarly, most Linux kernel developers maintain that drivers written for Linux must be released under the GPL -- but this presumably doesn't apply if BSD clones the driver interface, and the driver is written for BSD, and thus happens to work on Linux too. IANAL, and the FSF FAQ doesn't cover this case, so I dunno how this works.) On Fri, Jul 23, 2010 at 2:10 AM, Robert Leverington <rob...@rhl.me.uk> wrote: > In the past it has been concluded that extensions do not need to be > licensed under the GPL, and I think that is the general agreement at > the moment. Where? This contradicts the FSF's FAQ, and our own README file since r11770. We don't pursue people who violate the license in this way, but that doesn't mean we maintain that it's not a GPL violation. I assume Wikimedia's lawyers have not issued a statement on the matter. _______________________________________________ Wikitech-l mailing list Wikitech-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikitech-l
