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Thread: Licencing issue with Qt Open source

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    Default Licencing issue with Qt Open source

    I hope this is the right place to put this post... I am developing a music playing app for windows using Qt 4.1 open source edition. I intend to make the app open source itself, but I am wanting to link it against a closed source audio library. I would appreciate any indication as to whether this is OK or whether it would be in breach of the licence agreement.

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    Default Re: Licencing issue with Qt Open source

    IMO it would break the licence, but I'm not sure. What licence does the audio library have?

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    Default Re: Licencing issue with Qt Open source

    Thanks for the links. I've had a look but I'm not much good at this legal stuff, so I can't really make sense of them.

    The library I'm using is freeware, but not open source. However, I've been reading the Trolltech FAQ's and they seem to say that you don't have to use the GPL for software developed with Qt, just a compatible open source licence. Is this correct or have I misunderstood it?

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by thepasty
    they seem to say that you don't have to use the GPL for software developed with Qt, just a compatible open source licence. Is this correct or have I misunderstood it?
    They say clearly:
    Yes. The GNU GPL, GPL-compatible licenses, or any other approved open source license will do. The FSF.org and OpenSource.org web sites list approved software licenses.
    But the question is why wold you want to use other licence than GPL?

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    Default Re: Licencing issue with Qt Open source

    Thank you very much jacek. That definitely clarifies it for me. As for why I'm not using GPL, my program is linked to a "non-free" library, and from what I have gathered so far, this is not compatible with the GPL, so I need to use a more flexible open source licence.

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by thepasty
    my program is linked to a "non-free" library, and from what I have gathered so far, this is not compatible with the GPL.
    If I understand GPL FAQ correctly, you can use a non-free library:
    If the program is already written using the non-free library, perhaps it is too late to change the decision. You may as well release the program as it stands, rather than not release it. But please mention in the README that the need for the non-free library is a drawback, and suggest the task of changing the program so that it does the same job without the non-free library. Please suggest that anyone who thinks of doing substantial further work on the program first free it from dependence on the non-free library.
    You just can't distribute that library with your sources and you must clearly note that it depends on it. Also you will have to include a permission for linking your program with a non-free library (see http://www.gnu.org/licenses/gpl-faq....compatibleLibs).

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    Default Re: Licencing issue with Qt Open source

    The interpretations of the GPL are all over the board. Get ten Free Software advocates together, and they will have eleven interpretations! Here is one of mine: It is your application that is linking to the audio library, and not Qt, so this is acceptable. You should put in the exception notice, as mentioned in the second link jacek provided above.

    I would also urge you to at least look around for a true Open Source alternative. Even if you like your chosen library the best, the ability to use an alternative gives you (and your users) more flexibility, and prevents you from getting locked in to a proprietary solution.

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by Brandybuck
    You should put in the exception notice, as mentioned in the second link jacek provided above.
    IMO the exception is not appliable here, because it requires the owner of the opensource component (Trolltech) to acknowledge that.

    I would also urge you to at least look around for a true Open Source alternative. Even if you like your chosen library the best, the ability to use an alternative gives you (and your users) more flexibility, and prevents you from getting locked in to a proprietary solution.
    I second that. And if you provided a free (not as in free beer) alternative, then you can make that proprietary library optional and you won't break the GPL licence.

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    Default Re: Licencing issue with Qt Open source

    Thanks for the info. It sounds to me like, until I can get hold of an opensource alternative to the library, the GPL is best avoided. I've been in contact with Trolltech, and they say that there is nothing to stop me licensing the program under a more flexible licence like the BSD one, so that there is less trouble until I can make it all truly open source. I have to admit, I didn't think the fact that the Qt is under the GPL allowed you to do that, but the guy at Trolltech's customer support seems to think so, so thats good enough for now.

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by thepasty
    I have to admit, I didn't think the fact that the Qt is under the GPL allowed you to do that, but the guy at Trolltech's customer support seems to think so, so thats good enough for now.
    There are about 6 billion different opinions on what is and what's not allowed with GPL. That's the biggest problem with that licence.

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by thepasty
    I've been in contact with Trolltech, and they say that there is nothing to stop me licensing the program under a more flexible licence like the BSD one, so that there is less trouble until I can make it all truly open source.
    This is what I do. Some GPL interpretations say you can't do this, but the Trolls say you can and it's their code. Some people will say your code can now be "stolen", but that's rubbish. People who say that have their ideological blinders on so tight it's cutting off blood flow to the brain.

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by wysota
    Quote Originally Posted by Brandybuck
    I would also urge you to at least look around for a true Open Source alternative. Even if you like your chosen library the best, the ability to use an alternative gives you (and your users) more flexibility, and prevents you from getting locked in to a proprietary solution.
    I second that. And if you provided a free (not as in free beer) alternative, then you can make that proprietary library optional and you won't break the GPL licence.
    This is definitely the best way.

    But. The only problem can be the the license of Qt and the license of the non-free lib, because that's the software and the license where you don't have the copyright. So if Trolltech say:

    I have to admit, I didn't think the fact that the Qt is under the GPL allowed you to do that, but the guy at Trolltech's customer support seems to think so, so thats good enough for now.
    Than the Qt license is no longer a problem and you can use any Free Software license for your code. And say for example: "My code is licensed under GPL and as i special compliance you can link again lib xxx" That's absolutely no problem, because it's your code and your copyright.

    Quote Originally Posted by Brandybuck
    Some people will say your code can now be "stolen", but that's rubbish. People who say that have their ideological blinders on so tight it's cutting off blood flow to the brain.
    Code can never be stolen you can just copy it. The problem is another one: If your program depends on a non-free lib than the program as a whole is non-free for the user, because he can't use it on a free system.
    Last edited by BeS; 25th July 2006 at 22:11.

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by BeS
    Code can never be stolen you can just copy it.
    I don't know how about in your country, but in Poland it is called "stealing", as you're breaking the copyright.

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by wysota
    I don't know how about in your country, but in Poland it is called "stealing", as you're breaking the copyright.
    Maybe in common speech some people will call it "stealing" because they have learned the term through the propaganda campaign by the industry. But if you look at the text of your law i'm confident that you find it in the section about copyright as copyright infringement and not in the section about criminal acts as theft.

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by BeS
    Maybe in common speech some people will call it "stealing" because they have learned the term through the propaganda campaign by the industry.
    That "propaganda" was around long before software showed up on the scene. The common vernacular in English is to use "steal" for copying materials in violation of copyright. Like the "hacker versus cracker" argument, you are not going to be able to change the public's mind on this.

    I brought up the bit about BSD licensed code being "stolen" because that's a very common argument against unrestricted (non-copyleft) licenses. Even, in fact, from people with fsf.org emails who should know better. That's what I meant about ideological blinders.

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    Default Re: Licencing issue with Qt Open source

    Quote Originally Posted by Brandybuck
    That "propaganda" was around long before software showed up on the scene. The common vernacular in English is to use "steal" for copying materials in violation of copyright.
    If i violate copyright law, no public prosecutor will accuse me of "stealing" but of "copyright infringement" and no judge will adjudge me because i have "stolen" something but because i have infringed copyright. This are even two completely different sections in law.

    Like the "hacker versus cracker" argument, you are not going to be able to change the public's mind on this.
    I don't want to change publics mind but on the other hand i don't let the public (manipulated through the industry) change my mind and reality.
    If i ask people what the consider as "stealing" most will describe it as something like "take something away from me", that means at the end the thief has something which i don't have anymore. This just dosn't happens if you copy a file or sourcecode. The only thing is that you violate copyright if the license doesn't allow you to copy my file.

    I brought up the bit about BSD licensed code being "stolen" because that's a very common argument against unrestricted (non-copyleft) licenses.
    I don't hear this argument very often and i think it's wrong. The disadvantage of non-copyleft Free Software compared to copyleft Free Software is, that the non-copyleft software can be turned into non-Free Software which than will deny users freedom and i consider this as a bad thing for society as a whole. But even if someone turns my non-copyleft Free Software into non-Free Software he has nothing "stolen" from me, i have nothing lost.
    But i think we are way to much off-topic now.
    Last edited by BeS; 26th July 2006 at 15:24.

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