Proper license for plugins

[Benjamin Rossen]

Kelly,

GPL is probably still very widely used, although I do not know if it is the 
most common. It is not necessarily the best license to use. 

A very good paper discussing the main themes in the battle of the licenses was 
written by Bruce Perens (1999) "The Open Source Definition" In: Di Bona, 
Ockman & Stone Eds: "Open Sources: Voices from t he Open Source Revolution" 
O'Reilly. 

The whole book is rather a good read; strongly recommended. Some of the 
information about how to chose a license form, and where and how to tweak it 
for your needs, is of practical interest to anyone seeking to license a new 
project. 

Benjamin Rossen

See my other comments below.

On Sunday 16 January 2005 10:47, Kelly Anderson wrote:
> It would seem from my limited research that the GPL is the most common 
> license used for open source projects. My (primitive) understanding of GPL 
> is that if you improve code under the GPL, you must release or offer to 
> release the source code to the improvement. Fair enough.
> 
> Obviously, if you write a program on the Linux platform, you are not 
> required to release the source code under the GPL just because it runs on 
> Linux. You could actually sell such a program, right? I assume people are 
> actually doing this. 

The GPL explicitly permits you to sell your work, and prohibits you from 
preventing anyone making derivative works of your work from selling too. If 
your work is a derivative of a GPL licensed work then you must have a GPL 
license; you have no choice. Since you also cannot prevent someone else from 
giving their derivative away free you are not likely to get much selling your 
work unless you provide something else, like convenient packaging, updating, 
service, nicely printed handbooks (and some people pay for a nice logo - the 
Red Fedora was a stroke of genius - I have been paying for that for years.) 
This GPL license is very powerful in the legal sense, which is why so many 
people do not like it. The Open Source Definition is broadly framed, making 
it possible to design a license within the OSI framework, obtain the OSI 
approval and logo, and not be quite so commerce unfriendly. 

Now, to your question: merely operating on top of a GPL licensed operating 
system does not make it derivative. Linus Torvalds included the following 
preamble in the Linux license: 
" This copyright does *not* cover user programs that use kernel services by 
normal system calls - this is merely considered normal use of the kernel, and 
does *not* fall under the heading of 'derived works'. " 

If you start a new project to make software for the Linux platform, you are 
free to license it any way you wish. Closed Proprietary licenses are 
permitted... but they are usually bad business decisions. Don't do that, 
because your project shall die, irrespective of how brilliant your initial 
idea was.

> 
> I would guess, but am not sure, that if you created a plugin for Emacs, you 
> would not be required to release the source code.x

Yes. Emacs is GPL. You must make the source code available, you may not 
prevent anyone else from adding to your work and making new derivatives, and 
you are not permitted to use any other license form. Read the license for 
your other obligations under the GPL license and the law. This is very 
powerful legally, and you could be successfully prosecuted if you tried to 
hide the source code. The GPL license was designed by good lawyers working 
with Stallman to prevent free software going proprietary. 

Contrary to some legal opinions, the GPL has both copyright law and the power 
of contract law to support it. It is phrased to achieve this. For a contract 
to be legally binding you need the following: 
(1) Offer and Acceptance (a conscious affirming act by both parties)
(2) Consideration (both parties get something for what they give)
(3) It must be understandable.
Read the license; you shall see that all three are unequivocally present. 

> 
> If you were thinking about creating a core environment that could be 
> extended through a plug-in architecture (similar to how Emacs works) and 
> you wanted the plug-ins to be able to be either open source OR proprietary, 
> would the GPL be a reasonable choice or is there a better license out there 
> for this purpose?
> 
One size does not fit all. The GPL is seen as too restrictive, and somewhat 
enterprize unfriendly. Even Stallman knew that, and so made a more permissive 
license for his C libraries. 

I recommend that you read the guidelines on the Open Source Initiative pages 
to get an idea of what alternatives are possible. 

> -Kelly
>