On Thu, Nov 8, 2012 at 11:35 PM, "Claes Wallin (韋嘉誠)"
Sorry for bumping this discussion thread this late, but I discovered
Berkeley DB license* ("the BDB") and it made me think about what had been
Haven't looked at the BDB before, and I find it interesting. Taking into
account only the numbered points, it might be the shortest example of a
copyleft license in use in the field, even close to the shortest possible.
It's close in form to a BSD-like license plus source requirement.
BDB/Sleepycat is a pretty unusual license -- it doesn't have a
use-the-same-license condition, but does have a source condition, and
a really aggressive one at that ("complete source code for the DB
software and any accompanying software that uses the DB software").
I'm not certain how this can be GPL compatible or OSD compliant,
unless "uses" is interpreted in a way that just happens to be less
than or equal in scope to the GPL's conception of derivative works --
see section 9 of http://opensource.org/osd-annotated
I'm sure these have been discussed extensively but I wish the FSF and
OSI provided references on the relevant pages. :)
The FSF claims that the BDB is GPL compatible, I assume because it
specify anything outside the bare minimum, in particular does not restrict
any "further restrictions".
Presumably, though per above, I wonder about the justification.
Does it even propagate a guarantee of the four
freedoms to modified versions of the software?
On 2012-10-12 13:45, Bradley M. Kuhn wrote:
> Mike Linksvayer wrote on 9 August:
>> there are cases where unambiguously MPL code could be included in a
>> copyleft-next project, if only copyleft-next allowed for it.
> Honestly, I'm not convinced that a truly strong copyleft can allow
> unilaterally inclusion of other copylefted code -- even weak -- without
> bilateral compatibility clauses. We have to consider that such
> provisions while seemly safe on the surface may actually be manipulated
> to undermine the stronger copyleft by enterprising defense attorneys.
Is the BDB a counter-example to your thesis? Or is it not "truly strong"?
I don't think it is a counter-example because it isn't "truly strong"
in both (require same/similar license permissions, and require source)
obvious dimensions, but the question is whether a "truly strong"
copyleft license can usefully explicitly permit including works under
a weaker copyleft license, in a way that does not trigger the weaker
copyleft. If BDB/Sleepycat had any kind of licensing requirement for
derivatives, the FSF's statement about it being GPL compatible would
be more interesting for this discussion.
It seems to me that any license, that accepts whatever added
another license contains, will be forward-compatible with the more
restrictive license. Either by enumerating certain allowed further
restrictions, like the GPLv3 vs the AGPLv3, or by not explicitly forbidding
any, like the BDB.
The point about using a weaker license to undermine a stronger one stands,
whether if it means using a weaker, forward-compatible license to gradually
rewrite the code base, or if it means some currently unknown license
Yeah, I'd like all jututsu theories be put on the table. The security
of software freedom not optimally maintained through obscurity. ;-)