On 23/07/10 10:57, Andrew Fitzgerald 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.
Article:
http://markjaquith.wordpress.com/2010/07/17/why-wordpress-themes-are-deriva…
In my opinion, MediaWiki extensions are not derivative works unless
they copy substantial portions of core MediaWiki code. If an extension
merely uses the interface MediaWiki presents, then it is not a
derivative work, and the authors of MediaWiki have no right to place
conditions on its distribution.
To adopt an interpretation of copyright law which claims that merely
calling code constitutes a copyright violation of the code which is
called would, in my opinion, be a terrible stance for a free software
advocate to take. For instance, it would bring into question the
legality of all open source code which runs on top of the Windows
native API, such as 7-zip, not to mention Wine and Mono.
The two legal theories which would allow the use of an interface are:
* A function name or class name are not creative enough or substantial
enough to be eligible for copyright.
* A function name or class name is a small excerpt from a work, used
for the purposes of precisely referring to a larger part of the work.
Such reproduction of an excerpt is fair use. This is the same legal
theory which allows us to reproduce things like chapter titles and
character names in Wikipedia articles about copyright novels.
Aryeh Gregor wrote:
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:
When I agree to the GPL, and when I consent to allow my work to be
distributed under the GPL, I'm agreeing to the actual text of the
license. I'm not agreeing to every piece of nonsense that has ever
come out of Eben Moglen's mouth. I'm not even agreeing to the "How to
Apply These Terms to Your New Programs" section, which is explicitly
outside of the license itself.
There is no way the GPL can restrict code which is not licensed under
the GPL, and is not derivative (in the sense of copyright law) of any
GPL work.
In GPL version 3:
* Section 4 explicitly permits verbatim copying of GPL-licensed code,
and does not place any restrictions as to linking or calling non-GPL
code. Section 4 gives the author of a non-GPL extension permission to
copy the MediaWiki core. It also allows GPL extensions to non-GPL code
to be copied.
* Section 5 applies only to derivative works, and as I said, it would
be a terrible thing for the free software movement if it were to
attempt to apply this term to code which merely calls a copyrighted
interface.
If section 5 did apply to function calls, then every GPL program would
have to display prominent notices crediting the copyright holders of
every GPL library which it called, due to sections 5(a) and 5(d).
* Section 6 applies only to the distribution of non-source forms of
the work. Because MediaWiki and its extensions are only distributed in
source form, this section does not apply to it. But even for programs
written in C, section 6 does not restrict dynamic linking from GPL
programs to non-GPL programs, or vice versa.
Only the "how to apply these terms" section mentions linking:
"The GNU General Public License does not permit incorporating your
program into proprietary programs. If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library. If this is what you want to do, use the
GNU Lesser General Public License instead of this License."
But as I said, I never agreed to that and I don't intend to start now.
It comes after the words "END OF TERMS AND CONDITIONS".
The GPL does not restrict dynamic linking of non-GPL code to GPL code.
If it did, it could only be implemented by restricting distribution of
the GPL part, because the licensor has no right to place restrictions
on the copying of works which are not derivatives.
-- Tim Starling