[techtalk] KDE license?

[Rik Hemsley]

#if Sunnanvind
> Rik; you mentioned that you knew the KDE license.
> Could you or anyone else please explain why the KDE license is not bad?
> Including QT etc.
> Sunnan

Ok, KDE 1 needed to be linked to Qt 1. The fear that was most expressed
about the license of Qt 1 was that it could possibly allow a company
to take over Troll Tech and revoke all rights to use the code.

This would have meant that anyone who had written code that used the
Qt library would suddenly have no license to use libqt.

Now at KDE we knew that there was no way Troll Tech would do anything
to harm KDE itself. KDE itself doesn't generate cash for Troll Tech
but it introduces people to the Qt toolkit, so they were getting
more people paying for developer licenses for libqt.

The thing that happened then was that the KDE Free Qt Foundation was
set up. A contract was signed by Troll Tech and some of the KDE core
developers. This contract stated that if Troll Tech was ever bought
by another company then the current Qt source would be released
under the LGPL (I think, might have been the GPL) and therefore
anyone would be free to use it to fork a new version.

We KDE people would, in that case, have probably been the ones
to continue Qt development so it wouldn't have died.

The contract mentioned above is under Norwegian law.

Anyway, the QPL changes this situation.

1. If your code is Open Source, you do not have to pay Troll Tech
   for a license. You may charge for your software, but the source
   must be available.

So I can quite happily write code for KDE, and I could even sell
the software I write, so long as I don't hide my code.

2. If your code is closed source, you must buy a license, whether
   you charge for your software or not.

Again, this suits me, as I'm currently writing some closed source
software for a foreign company, using a Qt license which the company
has paid for.

What happens if you want to modify Qt ? Well, you have to send
Troll Tech your patches. This is to all intents and purposes the
same as the (L)GPL where you must make the source available. The
minor difference is that the changed code must go back to Troll Tech.

I think this is an advantage since it stops people thinking they
can simply pretend to release the source.

If you're working on a project that uses a modified copy of libqt,
you can do something as simple as set up a cron job that does a
diff between your version and the original and posts it to Troll Tech :)

What happens if Troll Tech are bought or go bust ? Well, we get
to keep both pieces. Qt is still QPL. If Troll Tech die, we (anyone) just
play with Qt. If they are bought, modified versions must still
be made available to Troll Tech.

What if you want to link to Qt ? Is there a problem ?
Well, only if you believe slashdot. Some people who either can't
understand the QPL or choose to spread FUD like to say that there's
still some kind of problem with Qt.

I think if there is any concern about Qt it is probably that it is
perceived that you can't take the code and fork your own version
of it. This isn't true. You're quite entitled to have your own
version of Qt. In fact, we have a modified version of Qt in the
KDE CVS right now. You just have to give your changes to Troll Tech.

They haven't asked us to mail patches to them yet - our version
is sitting on our CVS server and is available by CVS, CVSup, snapshots
etc. They're not that unfriendly :) Besides, many Qt developers have
been hired from the KDE Project, so we're kind of the same people :)

Disadvantages of Qt:

1. You must physically send your modifications, if any to Troll Tech.

2. You may not write closed source software unless your buy a 'professional
   license'.

Advantages of Qt:

1. You must physically send your modifications, if any to Troll Tech.

   This means that people are not tempted to hide their source or
   pretend they're making the source available when they're not.

2. It's controlled by a commercial company.

   This means that any license disputes (someone stealing Qt and refusing
   to send any modifications back to the owner) are handled by them and
   you don't have to sponsor someone to do it.

   It does _not_ mean that this commercial company gets to screw over
   users of Qt !

According to RMS, Linus Torvalds, ESR [1] etc Qt is most certainly Open
Source and they have no problem with it. I think the only people who
have a problem with it are those who want something for nothing. They
don't want to have to pay to write closed source software. Even though
they are free to charge for open source software, they want to be
able to do what you can with the LGPL which is to write commercial
closed source software without paying for the library.

I do agree that there was a problem with Qt 1. It was possible that
Troll Tech would be bought and Qt would be taken away. This was
fixed by The KDE Free Qt foundation.

Now, I can't see a single problem with Qt 2. Any complaints about
it now are usually made by making incorrect statements. People
who make these complaints are usually either just trying to bash
Qt for emotional reasons (they like _everything_ for free $$ or they
love their toolkit so much they want to knock down everything else) or 
they simply haven't read or have had trouble interpreting the QPL.

Cheers,
Rik

[1] Correct me if I got this wrong. I think these people are all in the list.

-- 
135. Displace the canon with attitude.

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