GPL License Effect on Plugins - Question & Discussion

6 Responses to “GPL License Effect on Plugins - Question & Discussion”

1. Kevin Dangoor Says:
   June 1st, 2006 at 10:42 am

   As I understand it, as long as Foo Bah does not include and distribute any GPL code, there is no way the GPL is involved with Foo Bah itself. Just because someone else can choose to download and use GPLed code with Foo Bah cannot impact Foo Bah itself.

2. Andrew Shuttlewood Says:
   June 1st, 2006 at 10:49 am

   Surely by using the interface that the application exposes it is a derivative work?

   That’s the argument of the GPL - that by writing to a GPL’d interface, you are building a derivative work - no matter the distribution requirement. Of course, this could go quite far - for example, something that merely called gcc could be arguably a derivative work of gcc if it was designed around it.

   I think in general it is wise to avoid developing plugins for GPL’d applications unless you are willing to GPL the plugin, or alternatively the license permits it.

3. Angsuman Chakraborty Says:
   June 1st, 2006 at 2:01 pm

   @Andrew

   GPL license states that - “You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works.”

   If Foo Bah doesn’t accept the GPL license, which is within his rights as he hasn’t signed it, he doesn’t get the right to distribute the GPL’ed program or its derivative works.

   The key points are - derivative works and scope of GPL license.

   The definition of derivative work is under the copyright law.

   According to the Copyright Act, a derivative work is

   a work based upon one or more preexisting works, such as a translation, musical arrangement, dramatization, fictionalization, motion picture version, sound recording, art reproduction, abridgment, condensation, or any other form in which a work may be recast, transformed, or adapted.

   A derivative work usually involves a type of transformation, such as the transformation of a novel into a motion picture. In the computer industry, a second version of a software program is generally considered a derivative work based upon the earlier version.

   via

   Also the GPL license states that:
   “Activities other than copying, distribution and modification are not covered by this License; they are outside its scope.”

   In wikipedia some rule of thumbs are defined:

   If the original software was designed to accept plug-ins or drivers using a defined mechanism, such a driver or plug-in does not form a derived work.

   link

   Looking forward to hear your thoughts and Kevin’s.

4. Angsuman Chakraborty Says:
   June 1st, 2006 at 2:07 pm

   Technology Law offices of Rosenlaw & Einschlag has this to say on derivative works:

   Here’s how I would decide in the edge cases that I described above:

   · The primary indication of whether a new program is a derivative work is whether the source code of the original program was used, modified, translated or otherwise changed in any way to create the new program. If not, then I would argue that there is not a derivative work.

   · The meaning of derivative work will not be broadened to include software created by linking to library programs that were designed and intended to be used as library programs. When a company releases a scientific subroutine library, or a library of objects, for example, people who merely use the library, unmodified, perhaps without even looking at the source code, are not thereby creating derivative works of the library.

   · Derivative works are not going to encompass plug-ins and device drivers that are designed to be linked from other off-the-shelf, unmodified, programs. If Linux is designed to accept separately-designed plug-in programs, you don’t create a derivative work by merely running such a program under Linux, even if you have to look at the Linux source code to learn how to do so.

   · In most cases we shouldn’t care how the linkage between separate programs was technically done, unless that fact helps to determine whether the creators of the programs designed them with some apparent common understanding of what a derivative work would look like. We should consider subtle market-based factors as indicators of intent, such as whether the resulting program is being sold as an “improved” or “enhanced” version of the original, or whether the original was designed and advertised to be improvable “like a library.”

5. Donald Smith Says:
   June 2nd, 2006 at 7:12 am

   “I am not a lawyer”

   They key point here is that these are all copyright issues. If you do not distribute or modify any GPL code, then how could you be breaking any copyright rules?

   - Don

6. Angsuman Chakraborty Says:
   June 2nd, 2006 at 10:41 am

   @Donald

   That’s a very good point. I have to agree with you on that.

   At this point it appears clear to me that any plugins for GPL software doesn’t fall under GPL, specifically if it isn’t shipped with the GPL’ed product. Yay.

Looking forward to hear your thoughts.