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Based on my understanding of the GPL FAQ (for v3, but I don't think
this part has changed substantially since v2), I think that linking
programs through things like XML is okay, or at the very worst a
"borderline" case according to FSF, as long as it's not directly making
function calls into the GPL'd main program:<br>
<br>
<a class="moz-txt-link-freetext" href="http://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins">http://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins</a><br>
<blockquote type="cite">If a program released under the GPL uses
plug-ins, what are the requirements for the licenses of a plug-in?<br>
<br>
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.
<p>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. This means the plug-ins must be released
under the GPL or a GPL-compatible free software license, and that the
terms of the GPL must be followed when those plug-ins are
distributed.</p>
<p>
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.<br>
</p>
</blockquote>
I don't know if it completely addresses Liam's first question, but my
understanding is that GPL'd programs are allowed to run on non-GPL'd
operating systems and vice versa through the following special
exception:<br>
<br>
<a class="moz-txt-link-freetext" href="http://www.gnu.org/licenses/gpl-faq.html#GPLIncompatibleLibs">http://www.gnu.org/licenses/gpl-faq.html#GPLIncompatibleLibs</a><br>
<blockquote type="cite">If the libraries that you link with fall within
the following exception
in the GPL:
<blockquote>
<p> However, as a special exception, the source code distributed
need not include anything that is normally distributed (in either
source or binary form) with the major components (compiler, kernel, and
so on) of the operating system on which the executable runs, unless
that component itself accompanies the executable.
</p>
</blockquote>
<p>
then you don't have to do anything special to use them; the requirement
to distribute source code for the whole program does not include those
libraries, even if you distribute a linked executable containing them.
Thus, if the libraries you need come with major parts of a proprietary
operating system, the GPL says people can link your program with them
without any conditions.<br>
</p>
</blockquote>
<br>
<br>
Kevin Reynen wrote:
<blockquote
cite="mid:9838564d0708301305k6b5fb147rcebf1f36b58b8044@mail.gmail.com"
type="cite"><br>
I'm going to ask one of the things Liam asked, but very specifically...
<br>
<br>
Are modules that create XML designed to be used by another piece of
software considered a "bridge"? Or is the XML considered the final
output of the GPL code and the point at which the GPL's influence
stops? <br>
<br>
I'm thinking of Flash photo gallery, but this could be applied to an
RSS reader as well. It fits the definatition of "seperate pieces of
software with a purpose to make a single unit of software out of those
parts". <br>
<br>
Is a module a bridge if it uses a standard like RSS, NewsML, or other
XML standardized for the purpose of moving or sharing data between
systems or applications... GPL'ed or not?<br>
<br>
- Kevin Reynen<br>
<br>
<br>
<br>
<div><span class="gmail_quote">On 8/30/07, <b
class="gmail_sendername">Liam McDermott</b> <<a
moz-do-not-send="true" href="mailto:liam@intermedia-online.com">liam@intermedia-online.com</a>>
wrote:</span>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Karoly
Negyesi wrote:<br>
<br>
> Before going any further, I want to make clear that I'm not<br>
> expressing approval or disapproval of this: I'm just relaying the<br>
> conclusions that were reached after several days of discussion and
<br>
> questioning with the FSF.<br>
Quite, now annoyingly I'm going to ask you some questions and probably<br>
repeat what you've already asked the FSF. My apologies in advance for<br>
this. :)<br>
<br>
> Why do these modules violate the GPL?
<br>
><br>
> 1) Under the FSF's accepted interpretation of the GPL, if a module
is<br>
> integrating Drupal and another PHP script, by calling one's APIs
when<br>
> triggered by the other for example, its purpose is to make a
single
<br>
> unit of software out of those parts.<br>
Then how is any GPL'd software allowed to run on Microsoft Windows? How<br>
are Opera, Adobe Flash or Java allowed to run on GNU/Linux?<br>
<br>
> 2) If multiple programs are operating together and functioning as
one
<br>
> unit, all the pieces must be GPL'd.<br>
I find this hard to believe. Take the vBulletin bridge for example, you<br>
want to build a site that uses Drupal for the CMS and vBulletin for the<br>
message board. Drupal distribute the CMS and the vBulletin bridge, both
<br>
available under the GPL, this integrates with vBulletin on the Web
server.<br>
<br>
Since the GPL is a copyright license it only comes into effect when<br>
software is distributed. The end user is allowed to mix whatever
license
<br>
combinations they want. That is why I am running GNU/Linux with Opera as<br>
my browser, Java and Flash installed, and some proprietary Windows<br>
software running under Wine.<br>
<br>
If you mean that it's technically a breach of the GPL to _provide a
<br>
service_ integrating software with incompatible licenses then I can see<br>
that you may have a point. Although if accused of breaching the GPL in<br>
this manner a good answer could be: 'the customer downloaded and
<br>
installed that piece of proprietary software, guvn'r.'<br>
<br>
I don't believe the Drupal maintainers have done anything wrong, they've<br>
only distributed GPL'd software. I can't imagine it would do the FSF's
<br>
public image any good to go after individual developers for something so<br>
trivial either. Most people would jump to BSD licenses faster than you<br>
can say: 'Richard Stallman!'<br>
<br>
This seems to be the same problem as graphics card vendors and their
<br>
binary drivers. They provide a binary (cross-platform) blob with some<br>
GPL'd 'glue' software between the blob and the Linux kernel. This has<br>
been argued--on both sides--but never really tested. As you pointed
out,
<br>
not taking any action will probably cause no problems.<br>
<br>
By the way: I am not a lawyer. I have no experience with law, only a<br>
vague understanding of the GPL. Am asking these questions as you<br>
probably have the answers already and if not you can query the FSF
again
<br>
(or provide us with an e-mail address).<br>
<br>
Thanks for the information! :)<br>
<br>
Kind Regards,<br>
Liam McDermott.<br>
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</blockquote>
</div>
<br>
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