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<== Date ==> <== Thread ==>

Subject: Re: Discussion about licenses, copyrights, business, and source code
From: "Johnson, Andrew N." <anj@aps.anl.gov>
To: "J. Lewis Muir" <jlmuir@imca-cat.org>
Cc: EPICS mailing list <tech-talk@aps.anl.gov>
Date: Fri, 24 Oct 2014 20:13:36 +0000
Hi Lewis,

Read all of the answer to the last question at http://www.gnu.org/licenses/gpl-faq.html#NFUseGPLPlugins and consider: If the act of loading and executing a plugin that just runs to completion and returns a result is regarded as "borderline" but just about acceptable, and communicating with one via shared memory is equivalent to dynamic linking, then any additional communication between a main program and a plugin, say through an I/O stream, is almost certainly to be on the wrong side of borderline.

I may be splitting hairs, but someone reading that using fork & exec to invoke a GPL plugin can free the program from the GPL's restrictions may start them thinking about using that to subvert the GPL and not realize that they're on a slippery slope to probable infringement.

- Andrew

-- 
Sent from my iPad

On Oct 24, 2014, at 01:42, J. Lewis Muir <jlmuir@imca-cat.org> wrote:

On 10/23/14 2:58 AM, Johnson, Andrew N. wrote:
On Oct 23, 2014, at 00:07, J. Lewis Muir <jlmuir@imca-cat.org> wrote:
See:

http://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins

To me, that supports what I said.

Read the following FAQ points as well, there are subtle distinctions
between whether your main application is GPL or your plugin is GPL,
and I think the example you pointed to was for a non-GPL plugin to a
GPL application.

Hi, Andrew.

Hmm...I don't see the subtle distinctions.  I see distinctions for
linking and whatnot, but I don't see distinctions for the "fork and
exec" case.  I very much so respect your opinion on this, so I'd really
like to understand.  There are three FAQ questions that talk about
plug-ins and they all start with a paragraph that says there are no
special requirements if the program uses fork and exec to invoke the
plug-ins.  Here are the three questions and the first paragraph of each
answer:

* If I write a plug-in to use with a GPL-covered program, what
 requirements does that impose on the licenses I can use for
 distributing my plug-in?

 It depends on how the program invokes its plug-ins. If the program
 uses fork and exec to invoke plug-ins, then the plug-ins are separate
 programs, so the license for the main program makes no requirements
 for them.

* Can I apply the GPL when writing a plug-in for a non-free program?

 If the program uses fork and exec to invoke plug-ins, then the
 plug-ins are separate programs, so the license for the main program
 makes no requirements for them. So you can use the GPL for a plug-in,
 and there are no special requirements.

* Can I release a non-free program that's designed to load a GPL-covered
 plug-in?

 It depends on how the program invokes its plug-ins. For instance, if
 the program uses only simple fork and exec to invoke and communicate
 with plug-ins, then the plug-ins are separate programs, so the license
 of the plug-in makes no requirements about the main program.

So, I'm not getting it.  What am I missing?!  Thanks for your patience.

Regards,

Lewis

Replies:
Re: Discussion about licenses, copyrights, business, and source code J. Lewis Muir
References:
Discussion about licenses, copyrights, business, and source code Emmanuel Mayssat
Re: Discussion about licenses, copyrights, business, and source code J. Lewis Muir
Re: Discussion about licenses, copyrights, business, and source code Johnson, Andrew N.
Re: Discussion about licenses, copyrights, business, and source code J. Lewis Muir
Re: Discussion about licenses, copyrights, business, and source code Johnson, Andrew N.
Re: Discussion about licenses, copyrights, business, and source code J. Lewis Muir

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