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

Subject: Re: Discussion about licenses, copyrights, business, and source code
From: "J. Lewis Muir" <jlmuir@imca-cat.org>
To: "Johnson, Andrew N." <anj@aps.anl.gov>
Cc: EPICS mailing list <tech-talk@aps.anl.gov>
Date: Tue, 28 Oct 2014 15:27:49 -0500
On 10/24/14 3:13 PM, Johnson, Andrew N. wrote:
> 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.

Hi, Andrew.

OK, I see where you're coming from.

Consider the FAQ question, "What is the difference between an
'aggregate' and other kinds of 'modified versions'?":

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

  ...

  "Where's the line between two separate programs, and one program
  with two parts? This is a legal question, which ultimately judges
  will decide. We believe that a proper criterion depends both on the
  mechanism of communication (exec, pipes, rpc, function calls within
  a shared address space, etc.) and the semantics of the communication
  (what kinds of information are interchanged)."

  ...

  "By contrast, pipes, sockets and command-line arguments are
  communication mechanisms normally used between two separate
  programs. So when they are used for communication, the modules
  normally are separate programs. But if the semantics of the
  communication are intimate enough, exchanging complex internal data
  structures, that too could be a basis to consider the two parts as
  combined into a larger program."

Granted, this question does not talk about the plug-in case
specifically, but it does talk about the concept of when two programs
are considered to be separate.  And it obviously talks about the case
of communicating via "pipes, sockets and command-line arguments"
and considering them to be two separate programs as long as the
communication is not intimate (e.g. transmitting internal data
structures).

I guess the crux of the issue is that no one really knows the answer
because it has never been litigated.  However, if the GNU organization
could make things clearer for the plug-in case and put it in the FAQ;
that would be a big help.  Who knows, maybe they would make it clearer
if a big organization (like the APS or ANL) asked about it!

If the GPL interpretation on this issue matches what you think, then the
GPL is a lot more viral than I thought.

Regards,

Lewis

Replies:
Re: Discussion about licenses, copyrights, business, and source code Benjamin Franksen
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
Re: Discussion about licenses, copyrights, business, and source code Johnson, Andrew N.

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