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Qt-interest Archive, February 2007
Re: Software with GPLed Qt and proprietary core?


Message 1 in thread

I stumbled upon a similar problem - I too need to have different core/gui 
license, although in my case, it is a bit different. The core is to be given 
away as open source, but under "less restrictive" license (BSD style, or maybe 
LGPL). Since I plan to have two interfaces (GUI in QT + commandline (not 
dependent on QT)) i will have to use some sort of dynamic linking (the core 
will be split into several "plugins", each of them doing some image 
manipulation). Since you can put BSD/LGPL code into GPL app (the license will 
be "converted" into GPL), putting BSD core inside should be probably fine ...

I don't care if instances of the core will be going away under GPL (let 
everybody see and use the code if they want), BUT I want to be able to 
re-release the core itself without GUI (commandline + plugins) under BSD style 
license (or LGPL) later (since there is high probability I'll need to use the 
core itself (excluding any GUI) in a proprietary system (i.e. as set of 
plugins doing the same thing in non-GPLed program)) ... is this possible while 
using QT? As the core is independent of any GPL code and is not based on any 
GPL code (well, I'll write it all by myself), I think it is possible to do, as 
GPL is distribution time license, though I am not lawyer. Can anybody clarify 
this?

Martin Petricek

Konrad Rosenbaum wrote:
> On Friday 19 January 2007 23:08, Michael Rice wrote:
>> There is absolutely no reason why you can't do this. The company needs to
>> have commercial Qt licenses for developing the proprietary GUI. If the
>> GUI application provides an "open" plug-in interface, then the people at
>> the university are free to develop and distribute open source plug-ins
>> using Qt for the closed source app.
> 
> Please define '"open" plugin-interface'. The way you describe it here it 
> sounds like a very serious violation of the GPL.
> 
> 
> 	Konrad

--
 [ signature omitted ] 

Message 2 in thread

IANAL,

On Saturday 03 February 2007 11:18, MP wrote:
> I don't care if instances of the core will be going away under GPL (let
> everybody see and use the code if they want), BUT I want to be able to
> re-release the core itself without GUI (commandline + plugins) under BSD
> style license (or LGPL) later (since there is high probability I'll need
> to use the core itself (excluding any GUI) in a proprietary system (i.e.
> as set of plugins doing the same thing in non-GPLed program)) ... is this
> possible while using QT? As the core is independent of any GPL code and
> is not based on any GPL code (well, I'll write it all by myself), I think
> it is possible to do, as GPL is distribution time license, though I am
> not lawyer. Can anybody clarify this?

If the core is independent of Qt and you own it, then you can (re-)license 
it however you want for the case in which you distribute without Qt.

If you link it with Qt (your "with GUI" option) its license has to be GPL 
compatible on distribution time.

A list of compatile licenses is here:
http://www.gnu.org/licenses/license-list.html#GPLCompatibleLicenses

Be careful with derivatives of the BSD-license. If they contain an 
advertisement clause then they are incompatible. (The boost license is 
fine.)



	Konrad

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