Hi Tyler
More comments inline:
On Sun, Feb 8, 2015 at 6:11 PM, Tyler Romeo <tylerromeo(a)gmail.com> wrote:
Not sure exactly what you mean. The MPL is compatible
with both GPL 2.0 and
3.0.
MPL v1.1 was not compatible with any version of the GPL, hence the
reason why Mozilla eventually multi-licensed their software under
MPL/GPL/LGPL (they pioneered the approach, IIRC). MPL v2 achieves GPL
compatibility by specifically naming GPL v2+, LGPL v2.1+, and AGPL v3+
as "Secondary Licenses", and then optionally allowing relicensing
(i.e. one-way conversion of the software to GPL/LGPL/AGPL) under
section 3.3. It basically bakes multi-licensing into the license
itself.
What I'm saying is that GPLv2 to GPLv3 is a
one-way direction. Once
code is licensed under v3, you cannot go back to v2. The Apache license is
only compatible with v3, and code under v2 cannot be combined with Apache
code, so the only way to add in Apache code to a GPL project is if the
entire project is v3.
By this logic, once MPL-licensed code is relicensed under GPL, you
cannot go back to MPL, so the only way to add GPL code to an MPL
project is if the entire project is GPL.
The fact that there's an option to upgrade the license to GPLv3 is
sufficient for GPLv2+ code to be compatible with Apache 2.0 code, in
the same way that the option to relicense MPL code as GPL code is
sufficient for GPL compatibility. You don't need to actually perform
the relicensing, you merely have to offer the licensee the option to
do so if they so desire.
I will assume good faith for the WMF. I was just
making a quick jab; I know
the WMF is not going to make MediaWiki proprietary.
Thanks for clarifying that.
However, I will not assume good faith for every other
software company out
there that may take MediaWiki, modify it or improve it in some way, and
then begin selling it as proprietary software. It's nice to think the world
is an ideal place where everybody shares their source code, but
unfortunately we are not living in the ideal, and in fact that is the
entire reason the GPL was written in the first place: in response to
companies acting in bad faith.
I think my experience is more-or-less in line with Stas, though I
think I still have more sympathy for the copyleft approach than he
has. I see the copyleft/permissive choice as more of a tactical than
a moral choice, and that I think permissive is going to be a more
effective long-term tactic to achieve the moral goals also sought by
proponents of copyleft. Downstream modifiers of software eventually
learn that keeping secret patches to upstream code is more hassle than
whatever "secret sauce" benefits they get.
Also, one cost of copyleft licenses is that they are much, much more
complicated than permissive licenses. Even though many people feel
comfortable with the compliance requirements of most OSI-approved
licenses, the permissive licenses can usually stand alone without an
FAQ, whereas an FAQ is required for just about all of the copyleft
licenses. That simplicity reduces a very real barrier to adoption.
Rob