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Re: Classpath code and licensing


Hi,

[Note that licensing questions should in general be send to
licensing@gnu.org since the FSF is the copyright holder of GCC and GNU
Classpath and sets the distribution terms. They also employ some people
trained in legal issues and as far as I know none of the current list
members is a legal expert. We also try to avoid answering tricky license
questions to make sure the FSF gives a clear message about what the
intention of the license is.]

On Tue, 2004-06-15 at 09:29, Robin Rawson-Tetley wrote:
> One of my contributors is working on part of the Java2D implementation
> for SwingWT. He was looking through the classpath sources and said
> there  was a lot of stuff he could reuse (AffineTransform, that kind
> of stuff), 

Cool!

> so what I wanted to know is:
> 
> 1. SwingWT is LGPL, are the licenses still compatible?

In general yes, the GNU Classpath (GPL + exception) license is
compatible with most things when you create an executable by combining
the GNU Classpath library with other modules. But note that the
exception part only holds for combining the GNU Classpath library with 
"independent modules" which is defined as "a module which is not derived
from or based on this library". So just mixing and matching source code
seems only possible under the normal GPL in your case.

> 2. If not, could we reuse the code and still distribute those source
>    files as GPL still?

Yes, you don't need to use the GPL+exception license when you
redistribute, but can just drop the exception statement and distribute
your derived work under the GPL. But as far as I know SWT itself, which
you combine with your own code to create a larger work, the SwingSWT
library, is distributed under the Common Public License, which is sadly
not GPL-compatible. (This might be a good reason to contact the Eclipse
board to ask them again to relicense SWT under something GPL-compatible,
or dual license it under the CPL and GPL or something. Last time we
asked they seemed positive about the idea, but didn't really seem to
have time to work out all the issues.)

> 3. Do we need to obtain anyone's permission? (I'm thinking not but
> just making sure - I assume the FSF is the copyright holder?)

Yes the FSF is the copyright holder. You don't ordinarily need
permission, but since since what you propose might violate the Classpath
license (or the SWT license), it is a good idea to ask for advice by
sending an email to licensing@gnu.org about this. Combining GPL, LGP,
GPL+Exception and CPL based code together in one larger work is tricky.

> If it's no go, then we'll carry on with our own implementation, but it
> seems silly to reinvent the wheel when there's other free code already
> out there.

Yeah, that would be silly. Make sure to mention explicitly what you are
trying to do with SwingWT (providing a free software alternative for
Swing that is usable now while our "pure" GNU Classpath one is still in
the works) to licensing@gnu.org. They might be able to work out some
solution to help out another Free Software project, with basically the
same objective as GNU Classpath, since in general the current Classpath
license is basically more permissive than the LGPL.

Feel free to forward this email to them (and/or CC me on your email) so
they can tell where I might not be completely right in the above
message.

Cheers,

Mark

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