GPL vs LGPL, in the context of adns ----------------------------------- 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 . Typically there are two or three kinds of situation where people make this request: the first is where another free software project currently using a GPL-incompatible licence, wishes to use adns. The second case, which often overlaps with the first, is where a free software project is currently using an MIT-like licence or the LGPL and fear `GPL infection'. The third case 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 1. 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 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 with the full text of the GPL-incompatible licence. However, I would usually prefer it if you could use a GPL-compatible licence for your project instead. I have already issued some waivers for certain projects. These are reproduced in LICENCE.WAIVERS. 2. GPL-avoiding projects (MIT licence, et al) --------------------------------------------- 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, 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 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. Proprietary applications of adns ----------------------------------- This applies to you if you are writing a proprietary program, by which I mean that you will not be distributing source code and not allowing users to modify and share your software; most likely you are doing this for your own (personal or corporate) financial gain. In this case the copyleft GPL licence does not meet your needs. Instead, you will need to negotiate a separate proprietary licence for adns. The List Price for a proprietary but LGPL-compatible application which uses adns is EUR150,000 per program per 10,000 users or part thereof, of which I will donate 25% to a Free Software organisation of my choice (as recognition for the contributions and help I have received from the Free Software communicy). Discounts may be available, particularly if I approve of your product. So, if you are serious about proprietary software, and paying for the software that you use, please contact me to negotiate a good deal. -- Ian Jackson 22.5.2004 Local variables: mode: text End: