The same old topic: Licensing.
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Not a lawyer too, but AFAIK you can distribute your closed-source commercial software with or without original Qt libraries if you use LGPL. And you con't need to provide source code by this license.
AFAIR there are some issues with static linking with Qt libraries. -
You do not need to distribute the application source code (ref. LGPL section 6) as long as the application is only dynamically linked to Qt (which is the ordinary case). Then the LGPL allows you to distribute your application under "the terms of your choice" (i.e. any license you like), provided that those terms "permit modification of the work [i.e., your application] for the customer's on use and reverse engineering for debugging such modifications."
If you modify Qt itself, then you must distribute the source code of your modified version of Qt if you want to distribute an application that uses it. You still do not have to distribute the source code of your application.
(Standard disclaimer: this is not official Nokia legal advice blah blah blah)
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[quote author="aavit" date="1275465885"]"permit modification of the work [i.e., your application] for the customer's on use and reverse engineering for debugging such modifications."[/quote]
To what extent is this required, do you just not sue them when they hack your app, or provide the ability to write plugins, or prpovide debug libraries (basically as good as source code, isn't it?)
This is very interesting, I love Qt personally... But I always thought the licencing thing would stop me producing closed source apps or commercial programs...
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[quote author="jorjpimm" date="1275466723"] To what extent is this required, do you just not sue them when they hack your app, or provide the ability to write plugins, or prpovide debug libraries (basically as good as source code, isn't it?)[/quote]
As I read it, the LGPL in this regard only places restrictions on the terms of the (optionally commercial, closed-source) license that you choose to distribute your application under. In effect, the LGPL says that that license may not contain things like "modifications or reverse-engineering is not allowed".
The FSF may provide more in-depth on this: http://www.fsf.org/licensing/
[quote author="jorjpimm" date="1275466723"] This is very interesting, I love Qt personally... But I always thought the licencing thing would stop me producing closed source apps or commercial programs...[/quote]
While that might have been an issue earlier, while Qt was under Trolltech's business model, it should not be now, after Nokia started releasing Qt under LGPL also (which happened about a year ago).
(Standard disclaimer applies)
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Have a look at this blog post for information about this directly from Qt legal:
"http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/(http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/)":http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/
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[quote author="MariusG" date="1275501216"]Have a look at this blog post for information about this directly from Qt legal:
"http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/(http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/)":http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/
[/quote]Has that page changed recently? Because I'm sure I have been on a page with the same title, and it used to be not so useful, but now looks very good.
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[quote author="MariusG" date="1275501216"]Have a look at this blog post for information about this directly from Qt legal:
"http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/(http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/)":http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/
[/quote]Thanks that made it all clear to me!
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Since comments at
http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/
are closed, I was wondering if I could have an answer at the following scenario/question:
If someone writes a closed-source Qt application for Windows based on the LGPL-licenced Qt framework, and if he/she doesn't change the libraries, and if he/she linked dynamically with the dlls (Qt for Windows) then:
a) if he/she doesn't provide the dlls but he/she only provides the exe
b) if he/she provides both the exe and the dllsdoes he/she has to provide the (unchanged) source code of the dlls?
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Stavros Filippidis, AFAIK in both cases you shouldn't provide code.
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@_Denis Kormalev_: Just to clarify, I am NOT referring to the source code of the application, but to the source code of the Qt libraries (QtCore4.dll, QtGui4.dll, etc). In any case, I am not a lawyer, I am just have these questioned unanswered. :)
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[quote author="Stavros Filippidis" date="1276707919"]@_Denis Kormalev_: Just to clarify, I am NOT referring to the source code of the application, but to the source code of the Qt libraries (QtCore4.dll, QtGui4.dll, etc). In any case, I am not a lawyer, I am just have these questioned unanswered. :)[/quote]
Yeah, I understood that question is about Qt sources. Anyway when you use Qt with LGPL license you need to provide link to Qt. And everybody who wants can take sources from Qt website.
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@Alexandra: In my opinion, it would be interesting if you would consider re-opening comments at
http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/
so that someone from Qt/Nokia's legal department could clarify additional questions that we could post there. ;)
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Stavros Filippidis, good idea. Also may be good will be to make FAQ about licensing issues. Alexandra Leisse, what do you (and other Trolls) think about it?
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[quote author="Alexandra Leisse" date="1276777620"]We agree. However, licensing (and law in general) unfortunately isn't easy to simplify while giving correct information...[/quote]
What about some simple use cases, specifying when and why you should use each licence... Although I suppose if it was that simple it would already exist...
A tricky topic....
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I just talked to our lawyer and she has already planned for a follow-up to mentioned "blog(Licensing blog)":http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/. To make it easier for her to figure out what is still unclear and would be good to address, I have started "a wiki page(Licensing wiki)":http://developer.qt.nokia.com/wiki/LicensingQuestions.
Please, add your questions/suggestions there and we do our best to provide you with answers.
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[quote author="Alexandra Leisse" date="1276877146"]I just talked to our lawyer and she has already planned for a follow-up to mentioned "blog(Licensing blog)":http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/. To make it easier for her to figure out what is still unclear and would be good to address, I have started "a wiki page(Licensing wiki)":http://developer.qt.nokia.com/wiki/LicensingQuestions.
Please, add your questions/suggestions there and we do our best to provide you with answers.[/quote]
I have just created this:
http://developer.qt.nokia.com/wiki/Question_Closed-source_application_scenario
But maybe I did something wrong and I do not see it at the Wiki! Could a TROLL please correct this? :)
EDIT:
I just noticed that I was supposed to EDIT the
http://developer.qt.nokia.com/wiki/LicensingQuestions
and NOT create a new wiki-page! So ... now I dit it (correctly!)!
Could a TROLL (please!) delete the
http://developer.qt.nokia.com/wiki/Question_Closed-source_application_scenario
which I shouln't have created the first place?