[Zope-dev] ZPL and GPL licensing issues

[Gregor Hoffleit]

On Wed, Jun 20, 2001 at 06:27:08PM +0200, Erik Enge wrote:
> On 20 Jun 2001, Federico Di Gregorio wrote:
> 
> > i am sure that the QPL and the ZPL are completely incompatible but
> > nobody cares because nobody really thinks that one is better than the
> > other...
> 
> I might be misunderstanding here, if that's the case I appologies.
> 
> Just to clarify, for us at Thingamy (and I'm quite sure this is the real
> case behind the license issues) it comes down to business-issues.  I do
> very much care whether or not I can use a GPL Zope Python Product with my
> ZPL/TPL Zope Python Product.  If I can't, and someone tells me I need to
> relicense my product as GPL it would be very bad.
> 
> An example could be if I had application G, Z, P.  G is a GPL'ed Zope
> Python Product, Z is a ZPL/TPL Zope Python Product and P is some
> proprietory stuff I developed for my client.  Now, if the proprietory
> application P interacts with my Z application and Z needs to become GPL,
> then that would/could require the proprietary stuff I did for the client
> to become GPL as well.

You're not allowed to distribute a derived work of GPL code with proprietary
code incorporated. I. e. if you want to use that GPL code in your work,
you'll have to make the proprietary code available under a GPL-compatible
license as well (not necessarily the GPL itself).

The Zope license doesn't even get into the play here. It's all between the
GPL and your proprietary license.

The crucial point is whether a work is a derived work of GPL code. The FSF
says that mixing pieces of proprietary and GPL scripts in an application is
a derived work indeed. Other people deny this.

    Gregor