[Product-Developers] Licensing of Plone addons

Servilio Afre Puentes afrepues at rhpcs.mcmaster.ca
Fri Jan 25 20:14:21 UTC 2013


Sean Upton <sdupton at gmail.com> writes:

> On Fri, Jan 25, 2013 at 9:11 AM, Steve McMahon <steve at dcn.org> wrote:
>> The FAQ is pretty good on these issues. To quote from it:
>>
>> """
> ...
>> It is possible to create an add-on product that does not exhibit these
>> behaviors (many generic Zope products that are not specific to Plone, and
>> some Plone themes, do not). Such products need not belicensed under the GPL.
>> """
>
> One option I have used is to split packages: "frameworky" stuff that
> can live "underneath" Plone and just depend on lower-levels of the
> stack (including the BSD-licensed framework components) go into an
> MIT-licensed package (my employer's legal folks prefer using this
> license when possible), while the application integration of it in
> Plone is GPLv2.  This had the positive side-effect of making me create
> a CMFDefault fixture for plone.testing (since plone.app.testing is
> GPL) -- incidentally, the CMFDefault fixture runs integration tests
> for the framework-level package much faster.
>
> You could certainly package proprietary/non-free or non-GPL FOSS
> components this way, and build a GPL'd plone app/product/add-on on top
> of them.

IANAL, but you can only do this when:

- For a proprietary component:
  - if it is covered by the system library exception; or
  - doesn't link to the GPL'ed work[1]
- non-GPL: if the license is compatible[2][3] with the GPL

> Also, AFAICT, mere aggregation is not subject to viral nature of GPL:

The viral nature of the GPL is a myth: it *never* changes the license of
your work, that you have to do by yourself, and only you can do it.

What it *does* is restrict you regarding what *use* you can make of the
GPL-licensed work. IIRC, privately you can combine it in whichever way
you want[4], once you want to distribute, the restrictions kick in.

Servilio

Footnotes:

[1] http://www.gnu.org/licenses/gpl-faq.html#GPLIncompatibleLibs

[2] http://www.gnu.org/licenses/gpl-faq.html#WhatIsCompatible

[3] http://www.gnu.org/licenses/license-list.html#GPLCompatibleLicenses

[4] http://www.gnu.org/licenses/gpl-faq.html#WhatDoesCompatMean


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