[OSGeo-Discuss] GIS_Libraries

[Landon Blake]

Here is a concrete example:

I believe OpenJUMP plug-ins must be released under the GPL, because they
are dynamically loaded and share data structures with the core program.

This is a good discussion. Thanks. :]

On a side note: I believe that UDig is released under the LGPL and it is
cross-platform. It might suit the needs of the original poster.

Landon
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-----Original Message-----
From: discuss-bounces at lists.osgeo.org
[mailto:discuss-bounces at lists.osgeo.org] On Behalf Of P Kishor
Sent: Tuesday, May 05, 2009 10:19 AM
To: OSGeo Discussions
Subject: Re: [OSGeo-Discuss] GIS_Libraries

On Tue, May 5, 2009 at 12:02 PM, Christopher Schmidt
<crschmidt at crschmidt.net> wrote:
> On Tue, May 05, 2009 at 11:55:47AM -0500, P Kishor wrote:
.
>>
>> Thanks Dan (and Christopher and others), I see the distinction now
>> between GPL and LGPL. However, I am reading the actual GPL text and
>> its extensive FAQ, instead of Wikipedia's interpretation of it, to
try
>> and sift through all the variations and exceptions to better
>> understand this now. Hopefully I will come out better informed from
>> this process. In the meantime, the distinction that you point out
>> between GPL and LGPL makes sense.
>
> http://www.fsf.org/licensing/licenses/gpl-faq.html#LinkingWithGPL
>
> "The combination itself is then available under those GPL versions."
>
.

This actually gets even more clear as mud... from the para above the
link provided above, we have the following --

----
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.

If the program dynamically links plug-ins, and they make function
calls to each other and share data structures, we believe they form a
single program, which must be treated as an extension of both the main
program and the plug-ins. In order to use the GPL-covered plug-ins,
the main program must be released under the GPL or a GPL-compatible
free software license, and that the terms of the GPL must be followed
when the main program is distributed for use with these plug-ins.

If the program dynamically links plug-ins, but the communication
between them is limited to invoking the 'main' function of the plug-in
with some options and waiting for it to return, that is a borderline
case.

Using shared memory to communicate with complex data structures is
pretty much equivalent to dynamic linking.
----

So, the above question is possibly closer in spirit to the OP that
started this thread. Can I create a commercial (and ostensibly closed
source, although that closed-source-ness of the program was not asked
for by the OP) program with "LGPL GIS SDK or library". The answer
would be yes. But, the answer would be yes with GPL as well, but then
we would get into whether or not the result would be open or closed
source, and what the license of the result would be. Yes, I muddied
the issue a bit by using the example of ShapeLib, but, perhaps that is
a good thing, because it does illustrate the need for thinking it
through carefully... what are we doing with the GPL program? Are we
linking? Are we doing a "simple fork and exec"? Do we have some other
borderline case?

Once again, the clearest advice would be -- if you think you have the
possibility of creating a business that is based on software worth
protecting its source, and yet want to use other free software, pony
up some cash up-front and get a real lawyer to advice you. Don't
listen to folks on mailing lists or read wikipedia articles... invest
in a lawyer. Otherwise, take the easy way out and stay free.

I actually quite like GPL's philosophy -- it doesn't restrict at all
what I do with GPLed software. It only stops me from restricting
others.

Puneet.
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