Re: asterisk and mysql_cdr
On Fri, Feb 25, 2005 at 10:20:28PM +0100, Jose Carlos Garcia Sogo wrote:
> > We were recently contacted by MySQL and informed that the MySQL client
> > libraries are now under GPL license and not LGPL license as before.
> >
> > Since Asterisk does allow exceptions to GPL, we are removing MySQL support
> > from standard Asterisk. We will, where appropriate, make it available via
> > a separate package which will only be usable when Asterisk is used completely
> > within GPL (i.e. not in conjunction with G.729, OpenH.323, etc). We
> > apologize for the confusion.
> >
> > You may find this in the new "asterisk-addons" package.
>
> In my opinion that removal was wrong and unnecessary. Copyright holders
> for a GPL package can put exceptions to allow distribution of binaries
> of their software linked to GPL-incompatible pieces of software. And the
> viral seed of GPL has nothing to do here, as the program who links to
> GPL incompatible software is GPL itself.
>
> If what the Asterisk author says above were true, his only problem were
> not mysql. The same for every program giving an exception for linking
> with OpenSSL or other different GPL incompatible software.
It sounds like Asterisk's authors wish to allow Asterisk to be linked
against GPL-incompatible libraries (which I assume "G.729" and "OpenH.323"
are examples of).
If they wish to do this, they need an explicit exception from the copyright
holders of *all* GPL works being linked against. This means that not only
must the Asterisk authors grant an exception; they also must have an exception
from the MySQL copyright holders, as well, and any other GPL libraries they
use.
Presumably, MySQL won't grant such an exception. Therefore, distributing
an Asterisk binary linked against both MySQL and G.729 violates the license
of MySQL. Exceptions granted by Asterisk can't fix this (though they can
make it worse if poorly implemented, as below).
> > > - Asterisk may be distributed under the terms of the GPL or under the
> > > terms of a modified-GPL: the GPL with some provisions to allow a
> > > number of libraries to be linked with it.
>
> No, Asterisk can only be distributed as GPL with an exception to it
> granted by copyright holder to be able to link asterisk with openssl and
> pwlib/openh323. Nobody but the copyright holder can remove that
> exception.
You must be able to remove the exception--that is, I must be able to
distribute the software under the plain GPL, without additional
exceptions. If I can't do so, then your exception itself is making
the license GPL-incompatible.
Another way of looking at it that may help understanding: the prohibition
of removing that restriction (and getting the original GPL back) is an
added restriction. GPL#6 explicitly prohibits this. For a work to be
GPL-compatible, it must be possible to distribute it under the terms of
the GPL--no more, and no less.
You *can* grant exceptions to the GPL, but if you prohibit the removal
of those exceptions, you've created something which is GPL-incompatible.
--
Glenn Maynard
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