[Qt-interest] LGPL compliance poll

[BRM]

----- Original Message ----

> From: Arnold Krille <arnold at arnoldarts.de>
> To: qt-interest at trolltech.com
> Sent: Fri, October 1, 2010 4:13:20 AM
> Subject: Re: [Qt-interest] LGPL compliance poll
> 
> On Thursday 30 September 2010 19:30:47 Josh wrote:
> > I know this has been  discussed at length, and have read the discussion,
> > and so don't want to  bring out all the arguments again. I would simply
> > like to poll those who  have 'closed-source' commercial apps on the list to
> > hear what they have  done. I would especialy appreciate examples of what
> > wording to use for  attribution to Qt.
> > 
> > So, what wording do you include in your  Qt-based LGPL 'closed-source'
> > commercial program?
> > 
> > For  reference: I'm going to sell a closed-source LGPL app to the general
> >  public based on Qt. I am going to dynamically link. I am going to
> >  redistribute Qt libs with my app. I will include a copy of the LGPL with
> >  my app, as well as a copyright notice for Qt in the app (wording?). I  plan
> > on referring users to nokia to download Qt as well as a notice that  they
> > may request the Qt source from me. Anything I've missed?
> > 
> > P.S. I know 'closed source' isn't a technically correct description,  I
> > simply mean that I'm not distributing the source of my LGPL  app...
> 
> I am not a lawyer but I am pretty sure that when your app is *GPL,  you _have_ 

> to provide access to the source code (for free! or for only  nominal fees like 

> for burning and sending the cd). No matter if its LGPL or  GPL.
> *GPL and 'closed source' doesn't fit together. And since you want to  sell this 
>
> for money, making my lawyer or Nokias lawyers talk to your lawyer  about it, 
> will make you loose that money very fast and maybe even very  big...

Let's put this to rest and quickly.

GPL requires that the using software be licensed under the GPL as well.
LGPL is kind of GPL with exceptions such that even closed source applications 
_can_ use it under certain rules - namely, you have to either (i) link fully 
dynamically, or (ii) you can statically link as long as you provide a method to 
relink to a user's build of the same source. In either case you have to provide 
access to the LGPL portion of the source for a given period - 3 years I think. 
This is all spelled out quite well in the LGPL license Section 4 
(http://www.gnu.org/licenses/lgpl.html).

This is by design and approved by the FSF.

While IANAL either, that is what the FSF puts forth. Sadly, the FSF leaves the 
more minor details to each community - like how the community decides to allow 
static linking. On this, Nokia has seemed to be silent (based on posts to the 
list).
 
> For applications there is actually no difference between GPL and  LGPL.

That depends on how the applications interface. The LGPL concerns itself 
entirely with how they interface.
If you use an LGPL application inside your close-source application then there 
is still the same difference between the GPL and LGPL.

>  The only difference between the two is that for libraries, LGPL allows  
>'closed source' 
>
> apps to link to this library without becoming GPL  themselves. Using GPL for 
> libraries in contrast forces any app linked to  this lib to be GPL too.
> That is the reason why Qt is LGPL and not GPL. Simply  so you can write 
> commercial, closed source (ie. non-GPL) apps with the free  edition of Qt.

Correct. But that's not what you were stating in the previous paragraph.
 
> The only occasion where you are allowed to use  GPL-libraries without your 
> becoming GPL is when that app is only used within  the firm/business unit that 

> wrote it in the first place. Which means when  the app isn't sold.
> On a side-note: This is the reason some folks invented  the AFL for 
web-apps...

Doesn't have anything to do with selling. I can sell you a copy of a 
closed-source application that utilizes GPL code so long as I do not 
_distribute_ the actual application to you.
As soon as I distribute the application the GPL license kicks in; until then I 
am free to do what I please.
 
> To come back to the point, when your app is  closed source (=> not *GPL) and 
> links to Qt, you have to state in your  on-line and written documentation, that 
>
> you use software licensed under the  LGPL. If you ship the libraries with your 

> app, you also have to include the  text of the license. And if you do any 
> modifications to the LGPL lib, you  have to publish these modifications because 
>
> they are too under the  LGPL-license... But when your modifications are "only" 

> bug-fixes they are  better to be sent to trolltech/nokia anyway.

Again correct.

Ben