1 GPL vs LGPL, in the context of adns 2 ----------------------------------- 3 4Several people have asked me to release GNU 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 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. 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 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 do that. 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 but 59GPL-compatible software to refer to adns in its source code. However, 60I think that exectuables (or compiled libraries) which contain or are 61dynamically linked against adns must be GPL'd; likewise executable 62programs (whether compiled or in an interpreted language) which 63require utilities from adns to function properly must be GPL'd. 64 65So, you can distribute your non-GPL'd program source which needs adns 66to compile (provided it's under a GPL-compatible licence), but people 67who wish to distribute binaries must do so under the terms of the GNU 68GPL. This may make sense for some GPL-avoiding free software 69projects; people can still make proprietary programs from your code, 70provided that they make some provision to replace adns with something 71whose copyright allows proprietary versions. 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 released 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 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 both such 106a program and a GPL'd program is not possible: either the combination 107would have to be distributed under the GPL (violating the restrictions 108made by 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 usually prefer it 114if you could use a GPL-compatible licence for your project instead. 115 116 117-- Ian Jackson 17.9.2000 118 119 120Local variables: 121mode: text 122End: 123