GPL vs LGPL, in the context of adns
-----------------------------------
-Several people have asked me to release adns under the GNU Lesser
+Several people have asked me to release GNU adns under the GNU Lesser
General Public Licence (LGPL, formerly the Library GPL) instead of the
`stronger' GPL. This file is intended to answer most of these
questions. If you still have questions or comments, please mail me at
this request: the first is where someone is developing a proprietary
program and wishes to make use of adns but doesn't wish to make their
program free software. The second case is where a free software
-project is currently using an MIT-like licence and fear `GPL
-infection'. The third case, which often overlaps with the second, is
-where another free software project currently using a GPL-incompatible
-licence, wishes to use adns.
+project is currently using an MIT-like licence or the LGPL and fear
+`GPL infection'. The third case, which often overlaps with the
+second, is where another free software project currently using a
+GPL-incompatible licence, wishes to use adns.
1. Proprietary applications of adns
Some free software projects prefer to avoid the GPL and other licences
which force the software always to be free. Instead they use
something like the MIT X licence, which allows proprietary versions of
-their software. I have to say that I don't understand why they do
-this, and think they are misguided, but that doesn't mean that they
-don't have a perfect right to.
+their software, or the in the case of some free libraries, the LGPL,
+which allows proprietary applications. I have to say that I think
+these people are misguided, but that doesn't mean that they don't have
+a perfect right to do that.
Some of these people think that merely writing to an interface
provided by GPL'd software will cause their program to become GPL'd
too, even if they don't distribute the GPL'd software. I don't think
-this is the case. I'm perfectly happy for non-GPL'd software to refer
-to adns in its source code or executables (eg, dynamic linking).
-However, if you distribute adns yourself then whether a program which
-uses it needs also to be GPL'd depends on the interpretation of the
-`work as a whole' and `mere aggregation' parts of the GPL.
-
-Whether you are distributing a `work as a whole' might depend on many
-things, but they key one to me is what the appearance is to a user.
-If the user knows that they are getting a collection of software
-rather than a single product, then it's probably an aggregation which
-works together. So, you can distribute both your (i) non-GPLd program
-source and/or binaries and (ii) adns source code or even binaries
-(provided the adns source is available as per the GPL), eg from your
-website, provided the user can tell that these are separate works and
-can tell which parts are which.
-
-But, if you package your program and adns together so that the user is
-no longer aware of adns as a separate work, then I think you are
-distributing a `work as a whole', and the whole work including adns
-and your software which depends on it must be GPL'd. This is of
-course not a problem if your non-GPL licence is GPL-compatible (see
-the next section): it just means that _when the whole lot is shipped
-together as one work_ it is covered by the GPL. People who wish to
-make proprietary works based on just your code can do so, provided
-they (or you) arrange for something to fill the hole left by the lack
-of adns.
+this is the case. I'm perfectly happy for non-GPL'd but
+GPL-compatible software to refer to adns in its source code. However,
+I think that exectuables (or compiled libraries) which contain or are
+dynamically linked against adns must be GPL'd; likewise executable
+programs (whether compiled or in an interpreted language) which
+require utilities from adns to function properly must be GPL'd.
+
+So, you can distribute your non-GPL'd program source which needs adns
+to compile (provided it's under a GPL-compatible licence), but people
+who wish to distribute binaries must do so under the terms of the GNU
+GPL. This may make sense for some GPL-avoiding free software
+projects; people can still make proprietary programs from your code,
+provided that they make some provision to replace adns with something
+whose copyright allows proprietary versions.
+
+However, this doesn't make much sense for the authors of LGPL'd
+libraries. All I can say to them is to ask which is more important:
+that their library be well-constructed and use all the best technology
+available as free software, or whether it is worth degrading quality
+of their library in order to allow proprietary programs to use it !
+
+To help the case of LGPL'd libraries for which adns is not a vital
+component - for example, a library which provides access to other
+libraries so that programs which use it need only use certain parts,
+I have released adns.h (just the public header file) under the LGPL as
+well as the GPL. See the copyright notice in adns.h for details.
+Note that this will not help you if it adns is essential to the
+functioning of your library, because all programs using your library
+must link against both your library and adns and so must be GPL'd.
+
+
+For some information and views from the Free Software Foundation on
+free software licensing, visit:
+
+ Various licenses and comments about them
+ at http://www.fsf.org/philosophy/license-list.html
+
+ Why you shouldn't use the Library GPL for your next library
+ at http://www.fsf.org/philosophy/why-not-lgpl.html
3. GPL-incompatible free software licences
Regrettably, there are a number of free software licences (and
semi-free licences) in existence which are not compatible with the
GPL. That is, they impose restrictions which are not present in the
-GPL, and therefore distributing a whole work which contains such a
-program and a GPL'd program is not possible: either the work would
-have to be distributed under the GPL (violating the restrictions made
-by the original author), or under the GPL-incompatible licence
+GPL, and therefore distributing a whole work which contains both such
+a program and a GPL'd program is not possible: either the combination
+would have to be distributed under the GPL (violating the restrictions
+made by the original author), or under the GPL-incompatible licence
(violating the GPL).
I may be prepared to make exceptions for such a licence. Please
contact me at <adns-maint@chiark.greenend.org.uk> with the full text
-of the GPL-incompatible licence. However, I would prefer it if you
-could use a GPL-compatible licence for your project instead.
+of the GPL-incompatible licence. However, I would usually prefer it
+if you could use a GPL-compatible licence for your project instead.
-There are a couple of common extra restrictions, and I make some
-specific extensions to my licence for adns below.
-3.1. BSD advertising clause and endorsement restriction
+-- Ian Jackson 17.9.2000
-The most notable and common extra restriction found in free software
-licences is the `obnoxious BSD advertising clause' (see Richard
-Stallman's article on the subject, available from www.gnu.org) and the
-endorsement restriction.
-
-The problem with the advertising clause isn't that the sentence
-required, referring the the Regents of the UC Berkeley, is awkward.
-The problem is that if everyone contributing to a large project gets
-such a mention the number of sentences required becomes very large;
-however, it is unfair for some people to get credit and others not to.
-
-I disapprove of these clause, but I recognise that it may be difficult
-for some people to get them removed from particular programs.
-
-So, I hereby make an extension to my licence for adns:
-
- You may alternatively distribute adns under the GNU GPL version 2
- with the following banner and either one or both of the following
- additional restrictions, to be inserted at the end of section 1:
-
- ADDITIONAL RESTRICTIONS:
- (The permissions granted in this licence only apply if you comply
- with the following restrictions:)
-
- (a) All advertising materials mentioning features or use of the Program
- (or a work based on the Program, GPL section 2) must display the
- following acknowledgement for each author, copyright holder or
- group of authors or copyright holders:
-
- This product includes software developed by PERSON OR GROUP.
-
- where PERSON OR GROUP is the name of the (group of) authors or
- copyright holders, in the form in which they reasonably wish
- themselves to be identified in such acknowledgements. A
- reasonable alternative form of words must be used if requested
- by the person or group.
-
- The desires of the persons or groups are to be inferred from
- statements made about the desired form of such acknowledgements
- by these persons or groups in their own copyright notices and
- licences. Such statements are to be considered part of the
- appropriate copyright notice that the GPL requires you to
- publish (section 1).
-
- This credit must be given for every author and copyright holder
- of the Program or the work based on the Program, in so far as it
- reasonably possible to determine who the author(s) and copyright
- holder(s) are.
-
- (b) None of the names of the copyright holders and authors of the
- Program or works based on the Program may be used to endorse or
- promote the Program or works based on the Program without
- specific prior written permission.
-
- Any rephrasing of this restriction provided by authors or
- copyright holders in their copyright notices is to be retained
- as part of the appropriate copyright notice that the GPL
- requires you to publish (section 1).
-
-
---- Ian Jackson 9.5.1999
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