Remove extra extensions since UCB have withdrawn the advertising clause.
[adns] / GPL-vs-LGPL
CommitLineData
71ede3cd 1 GPL vs LGPL, in the context of adns
2 -----------------------------------
3
4Several people have asked me to release adns under the GNU Lesser
5General Public Licence (LGPL, formerly the Library GPL) instead of the
6`stronger' GPL. This file is intended to answer most of these
7questions. If you still have questions or comments, please mail me at
8<adns-maint@chiark.greenend.org.uk>.
9
10Typically there are two or three kinds of situation where people make
11this request: the first is where someone is developing a proprietary
12program and wishes to make use of adns but doesn't wish to make their
13program free software. The second case is where a free software
249cf48a 14project is currently using an MIT-like licence or the LGPL and fear
15`GPL infection'. The third case, which often overlaps with the
16second, is where another free software project currently using a
17GPL-incompatible licence, wishes to use adns.
71ede3cd 18
19
201. Proprietary applications of adns
21-----------------------------------
22
23So, let me get this straight. You're writing a proprietary
24program, by which I mean that you will not be distributing source code
25and not allowing users to modify and share your software; most likely
26you are doing this for your own (personal or corporate) financial
27gain.
28
29However, you want to take advantage of adns, software which I have
30spent my time and effort on, and which I release as free software so
31that everyone can improve, share and use it.
32
33Don't you think that is a little hypocritical ? I'm sorry, but I
34don't want you to just take my nice convenient software, without
35giving something back to the free software community or giving the
36same rights to your users as I do to you.
37
38If you really aren't the nasty kind of person I've described here, for
39example if you have a good reason other than your own selfishness for
40wanting to restrict distribution of your program, then perhaps you
41should contact me to discuss it.
42
43
442. GPL-avoiding projects (MIT licence, et al)
45---------------------------------------------
46
47Some free software projects prefer to avoid the GPL and other licences
48which force the software always to be free. Instead they use
49something like the MIT X licence, which allows proprietary versions of
249cf48a 50their software, or the in the case of some free libraries, the LGPL,
51which allows proprietary applications. I have to say that I think
52these people are misguided, but that doesn't mean that they don't have
53a perfect right to.
71ede3cd 54
55Some of these people think that merely writing to an interface
56provided by GPL'd software will cause their program to become GPL'd
57too, even if they don't distribute the GPL'd software. I don't think
58this is the case. I'm perfectly happy for non-GPL'd software to refer
249cf48a 59to adns in its source code. However, I think that exectuables (or
60compiled libraries) which contain or are dynamically linked against
61adns must be GPL'd; likewise executable programs (whether compiled or
62in an interpreted language) which require utilities from adns to
63function properly must be GPL'd.
64
65So, you can distribute your non-GPL'd program source which needs adns
66to compile, but people who wish to distribute binaries must do so
67under the terms of the GNU GPL. This may make sense for some
68GPL-avoiding free software projects; people can still make proprietary
69programs from your code, provided that they make some provision to
70replace adns with something whose copyright allows proprietary
71versions.
72
73However, this doesn't make much sense for the authors of LGPL'd
74libraries. All I can say to them is to ask which is more important:
75that their library be well-constructed and use all the best technology
76available as free software, or whether it is worth degrading quality
77of their library in order to allow proprietary programs to use it !
78
79To help the case of LGPL'd libraries for which adns is not a vital
80component - for example, a library which provides access to other
81libraries so that programs which use it need only use certain parts,
82I have release adns.h (just the public header file) under the LGPL as
83well as the GPL. See the copyright notice in adns.h for details.
84Note that this will not help you if it adns is essential to the
85functioning of your library, because all programs using your library
86must link against both your library and adns and so must be GPL'd.
87
88
89For some information and views from the Free Software Foundation on
90free software licensing, visit:
91
92 Various licenses and comments about them
93 at http://www.fsf.org/philosophy/license-list.html
94
95 Why you shouldn't use the Library GPL for your next library
96 at http://www.fsf.org/philosophy/why-not-lgpl.html
71ede3cd 97
98
993. GPL-incompatible free software licences
100------------------------------------------
101
102Regrettably, there are a number of free software licences (and
103semi-free licences) in existence which are not compatible with the
104GPL. That is, they impose restrictions which are not present in the
105GPL, and therefore distributing a whole work which contains such a
106program and a GPL'd program is not possible: either the work would
107have to be distributed under the GPL (violating the restrictions made
108by the original author), or under the GPL-incompatible licence
109(violating the GPL).
110
111I may be prepared to make exceptions for such a licence. Please
112contact me at <adns-maint@chiark.greenend.org.uk> with the full text
113of the GPL-incompatible licence. However, I would prefer it if you
114could use a GPL-compatible licence for your project instead.
115
249cf48a 116--- Ian Jackson ...
117
71ede3cd 118
119Local variables:
120mode: text
121End: