Qt license policy and paid for apps
asked 2014-04-23 12:17:32 +0300
It may be somewhat premature to ask this as there is currently no support (related) for paid for apps in Harbour.
I was however wondering how the licensing for paid apps would work. Specifically the licensing of Qt from Digia. Digia is licensing Qt under GPLv3 and LPGLv2 and a commercial license. LGPLv2 section 2.c says:
- You must cause the whole of the work to be licensed at no charge to all third parties under the terms of this License.
and GPLv3 section 5.c says:
- You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it.
Neither LPGLv2 or GPLv3 prohibit anyone from charging for the application (sources or object code), they do in fact explicitly allow it, but they also require the sources to be released under GPLv3 and LPGLv2.
So should someone wish to create a proprietary Sailfish app it would seem to me that it requires licensing either Qt Mobile from Digia at €109/month or the enterprise version at some undefined price that needs to be agreed with Digia separately. http://qt.digia.com/Try-Buy/
Was there some special clause in the Sailfish SDK that I missed, that allows developing non-free Sailfish apps without separately licensing Qt from Digia with a commercial license? GPLv3 to my knowledge requires all of the program that uses a GPLv3 library also to be GPLv3. LPGL doesn't, but I don't understand their interaction with each other.
I am not an expert on copyright law, so could someone clarify if I've understood this correctly. Also could someone from Jolla shed some light on this.
Given that the Android dev license is free (as in beer), and Apple charges (or at least used to) some €70/year for AppStore(tm) access, €109/month seems quite pricey. You really need to believe in your app to take that on, all upfront.
IANAL, but Section 6 of LGPLv2 provides an exception for distributing executables, and the conditions under which this can be done. (In particular, it does not require that you license your work under LGPL).
vvvv ( 2014-04-23 17:59:35 +0300 )editThat seems clear enough, however I'm not entirely sure what the GPLv3 is doing there. Qt is licensed under both not one or the other, and the Sailfish SDK installer requires you to accept both.
2Ti ( 2014-04-23 18:56:15 +0300 )editThe debugger (GDB) that gets installed with the SDK is licensed GPLv3, which is why the license is shown in the installer.
kaltsi ( 2014-04-23 23:27:25 +0300 )editQt is not licensed under both GPL and LGPL, but eitherGPL or LGPL. http://qt-project.org/doc/qt-5/licensing.html
vvvv ( 2014-04-24 10:47:23 +0300 )edit@vvvv Ah, I see. So the GPLv3 is there so that people can use Qt in projects that already have other GPLv3 stuff in them. Thanks for the clarification. You want to put that down as an answer so I can accept it.
2Ti ( 2014-04-24 11:05:08 +0300 )edit