[Zope-dev] ZPL and GPL licensing issues

[Federico Di Gregorio]

On 21 Jun 2001 11:39:37 -0400, Jim Penny wrote:
> On Thu, Jun 21, 2001 at 05:18:40PM +0200, Federico Di Gregorio wrote:
> > On 21 Jun 2001 11:08:30 -0400, Jim Penny wrote:
> > [snip]
> > > OK, consider this from another point of view.  If I have an operating
> > > system may I install a piece of GPL software on the operating system?
> > > May I redistribute the operating system?  With the GPL software?
> > > May I invoke/run the GPL software?
> > > 
> > > My understanding is that the answer to every one of these is yes.
> > 
> > yes. only if it is free. only if it is free. yes, but only because gpl
> > allows for gpl code linking with the major components of the os even if
> > they are proprietary.
> 
> Uh, you might want to reconsider the "only if it is free" parts.  After
> all Interix had a business of selling GPL software for a non-free
> OS.  Now Microsoft has that business (NT Services for Unix Pack).
> IBM distributes gcc and perl.  Cygwin sells GPL software for non-free
> OS's.

ops. ok, poorly worded. third parties can distribute only if the os is
free, vendor can do as he please, obviously...

[snip]
> > err, no. if you write an external module using only python code, as long
> > as you use a gpl-compatible python to run zope, you can call your
> > external code from zope. if you write a product suclassing dc code,
> > you're effectively 'linking' and gpl limitations apply. 
> 
> GPL limitations apply to whom:  To you, the developer?  To a
> downstream user invoking the product via dtml-call or dtml-var or their
> pythonish equivalents?  To a downstream developer who modifies your
> product and redistibutes the modified product?  To a downstream
> developer who writes a component that invokes the GPL component?
> 
> In my mind the only sensible answers are developer - no,
> user - no (but see Jerome Alet's codacil), downstream modifier - yes,
> downstream developer who uses - no.
> 
> The only other sensible option is that, indeed, no one may distribute
> GPL components for Zope, including the original developer.

as i said before, writing gpl code subclassing zope is a non-sense. even
the author cannot, imho, redistribute its work with a plain gpl attached
to it. the gpl says that if you link with gpl code *all* the code should
be gpl or gpl-compatible (major os components like clibs, compilers, etc
are an exception). so even the author cannot do that without licensing
under gpl plus some exception ("as a special exception you're allowed to
link this code with zope or any other zope product distributed under the
zpl".) see the (in)famous gpl vs. qt thread in the debian mailing lists
for an in-depth analisys of this problem.

ciao,
federico

-- 
Federico Di Gregorio
MIXAD LIVE Chief of Research & Technology              fog@mixadlive.com
Debian GNU/Linux Developer & Italian Press Contact        fog@debian.org
                      The number of the beast: vi vi vi. -- Delexa Jones