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Re: Subversion change of license -- where was the discussion?

From: Stefan Sperling <stsp_at_elego.de>
Date: Mon, 28 Sep 2009 00:04:32 +0100

On Sun, Sep 27, 2009 at 09:58:13PM +0200, Michael Haggerty wrote:
> how it was decided. Did I simply miss the discussion, or did the
> discussion took place in a loftier forum to which I am not party?

The discussion was on the full-committers mailing list, which all
members of the Subversion Corporation, which is the copyright holder
of Subversion, are part of. See http://subversion.org/

> According to advice that I solicited from
> licensing_at_fsf.org with respect to the cvs2svn project, the old CollabNet
> license was compatible with GPLv2,

They have given your advice which is inconsistent with their
own website: http://www.gnu.org/licenses/license-list.html

  Apache License, Version 1.1

    This is a permissive non-copyleft free software license.
    It has a few requirements that render it incompatible with
    the GNU GPL, such as strong prohibitions on the use of
    Apache-related names.

 Apache License, Version 1.0

    This is a simple, permissive non-copyleft free software license
    with an advertising clause. This creates practical problems like
    those of the original BSD license, including incompatibility
    with the GNU GPL.

So our old licence was not compatible with the GPL either.
The old licence was a sort-of apache 1.1 or sort-of apache 1.0 licence.
In any case, it had an advertising clause. Quote:

  3. The end-user documentation included with the redistribution,
     if any, must include the following acknowledgment:
        "This product includes software developed by
         CollabNet (http://www.Collab.Net/)."
     Alternately, this acknowledgment may appear in the software itself,
     if and wherever such third-party acknowledgments normally appear.

So this issue has always existed.
It's *not* the recent licence change which has caused this problem.

Furthermore, as far as I understand, the incompatibility comes from the
GPL side, not from the Apache side.
Because according to the GPLv2 a licence may not enforce restrictions other
than those listed in GPLv2 to be compatible, people who licence code which
links to Subversion under the GPL create a theoretical problem for downstream
consumers of their GPL'd code.
Consumers cannot distribute the combined work without violating the GPL.
But they aren't violating Subversion's licence if they do this.

The restriction the GPL does not list is that your licence to Subversion
will be revoked if you ever try to legally enforce a software patent on
code you contributed to Subversion or added to a version of Subversion
you are distributing.
There is very little chance that this clause will ever matter in practice
because we'd have to be tricked into accepting code by a contributer who
also filed a software patent on said code in any jurisdiction. I don't think
we would under any circumstances accept such code if we were aware of the
Or, I guess any downstream distributor of a combined work consisting of your
code and Subversion would be affected if they had a patent on code they added
to their modified distribution and started suing someone based on their
patent. Then their licence to Subversion would terminate, but their licence
to the GPL'd code would not.
In practice, this additional restriction only gains meaning in an emergency
situation, and affects bad guys. Under normal circumstances, nobody will
sue anyone, and the restriction not listed in the GPL won't have any effect.

It is (and always has been, see advertising clause) up to you to decide
whether you want to put downstream consumers of your GPL-licenced code at
risk of GPL-violation, by linking your GPL'd code to Apache-licensed code
and distributing the result. It's *your* decision to license your code this
way. But more importantly it's *your* decision to enforce your copyright if
you think that linking your code to Subversion constitutes a violation of
the licence agreement.

I believe that the copyright holders to GPL'd code could add text like the
following to the GPL licence to avoid this problem:
  This program is released under the GPL with the additional exemption
  that compiling, linking, and/or using Subversion is allowed.
Example taken and adapted from http://openssl.org/support/faq.html#LEGAL2
Could you ask the folks at FSF if this would make them happy?

See also http://www.apache.org/licenses/GPL-compatibility.html


Received on 2009-09-28 01:04:50 CEST

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