[development] Modules that integrate non-GPL PHP apps violate the GPL.

Thomas Barregren thomas at webbredaktoren.se
Sat Sep 8 09:51:18 UTC 2007

Angela Byron skrev:
> On 7-Sep-07, at 3:23 PM, Dries Buytaert wrote:
>> On 30 Aug 2007, at 09:08, Jeff Eaton wrote:
>>> For quite some time, it has been commonly understood in the Drupal 
>>> community that non-GPL software (like a third-party PHP message 
>>> board system) can be integrated into Drupal legally by using an 
>>> intermediary 'bridge' module. After some in-depth emails with the 
>>> Free Software foundation's license gurus, it's become clear that 
>>> this is NOT the case.
>> Because some people e-mailed me in private about this; it's going to 
>> take me a couple more days to respond to this thread.  I'm also going 
>> to consult some other Open Source projects about this.  In the mean 
>> time, keep on discussing as all input is valuable before we refine 
>> our stance. :)
> Ok, I was keeping quiet in this thread, but since you seem to want 
> input...
> IMO, the only thing we can do is exactly what Joomla! did:
> - Do not fork the GPL by creating our own interpretation of it (adding 
> exceptions, etc.).

We should definitely *not* fork GPL. That would be committing hara-kiri.

But adding a "FOSS Exception" or "Linked Under Controlled Interface 
Exception" is *not* forking. On the contrary! It is a proper way to 
solve situations like the one we are discussing. The technique is 
proposed and fully described with template and everything on FSF/GNU's 
web site:

    * http://www.gnu.org/licenses/old-licenses/gpl-2.0-faq.html#GPLIncompatibleLibs
    * http://www.gnu.org/licenses/old-licenses/gpl-2.0-faq.html#LinkingOverControlledInterface

In fact, it *might* be necessary to add a FOSS Exception for the 
PHP-license. Why? The PHP-license is not compatible with the GPL. That 
itself doesn't prevent PHP-programs to be distributed under GPL. But 
since Drupal *make use* of GD and other libraries distributed under the 
PHP-license, it is possible to argue that Drupal in part is a derivative 
of GD and the other libraries. If this cannot be deemed to fall under 
the platform exception in GPL, it is not possible to distribute Drupal 
under GPL without adding a notice saying that it is okay. Again, adding 
a such notice is not forking GPL.

> Adding exceptions anyway is a physically impossibility; you'll never 
> find all of the copyright holders of Drupal to sign off on it, and 
> many of us would oppose such an action.

I am not completely convinced that it is a "physically impossibility". 
After all, it is a limited number of people who have committed code to 
the core. I suppose most of them are still members of Drupal.org, and 
hence possible to get in contact with. Why not try? Likely, a vast 
majority of all core contributors will accept a "FOSS Exception" and 
possible also a "Linked Under Controlled Interface Exception" for a 
"Module Programming Interface" (e.g. hooks and some utility functions).

There will of course be some persons who cannot be contacted or who 
won't give their permission. But their numbers will probably be very 
small, and therefore easy to just replace their code with new code with 
the same functionality. After all, copyright doesn't protect ideas, only 
the expression of ideas.

BTW, something similar has been done before, and in much larger scale, 
namely BSD.

> - Remove any code from our repositories that combine with non-GPLed 
> code. This would be things like SMF, vBulletin, CiviCRM integration 
> bridges. If those companies want to put themselves in potential legal 
> jeopardy by providing bridges for our CMS, then they can host it on 
> their own infrastructure, not ours, or they can dual-license their 
> software so that it's GPL-compatible.


> I think a lot of the discussion in this thread is just out-right 
> denial. I'm quite sure that the folks at Open Source Matters looked 
> into this issue extensively before Joomla! made their decision to quit 
> distributing their SMF bridge, especially since the vast majority of 
> their users are non-programmers who would never in a million years be 
> able to create one by themselves, and since Joomla! does not have a 
> core forum system of their own.

Very good point. I can only add, for those who think they can prove GPL 
unfeasible, that GPL has been around and scrutinized for 18 years.

> On a personal note, I fully support the viral nature of GPL, and see 
> it as a critical feature, not a bug.The GPL is part of the primary 
> reasons I spend my time working on applications like Drupal; it 
> preserves the freedoms I was given for all future users of my code.

I can only agree.

Best regards,

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