Some notes beforehand:
- Insulting others in relation to licensing matters may result in an immediate one week forum ban.
- This post is in NO way a legally binding text, it is NOT an addendum/exception to the GNU GPL.
- This post is only a clarification of an opinion a number of Spring developers share.
- This post does not oblige us to take action against those not respecting this opinion.
There has recently been some discussion on these forums on how and why the engine's GNU GPL would affect AIs for the engine. From this discussion it appeared quite some things aren't entirely clear. This post is meant to alleviate this, by giving some clarification on how we, Spring engine developers, think the GNU GPL applies to AIs for the Spring engine.
- We think an AI for Spring is "linking" to the engine, to speak in the terms of the GPL: the engine calls into AI code and AI code calls back into the engine. In practice this means AIs need to be licensed at least under the terms of the GNU GPL.
- AIs can probably* be licensed under other licenses, as long as the other license doesn't conflict with the GPL. (e.g. something like the modified BSD or zlib license should be fine)
- AIs can probably* be dual licensed as GPL and another license (e.g. LGPL, modified BSD, zlib), in case you want to allow AI code to be re-used in non-GPL contexts too. In this case, be sure all contributions are dual licensed too!
- Some thought that in the past an exception for AIs had been made. The project and forum history do not seem to contain any reference to such an exception however, so for all practical purposes it does not exist.
- There are no plans to add an exception to the engine's license in the foreseeable future.
We hope this clarifies the situation for all involved with Spring, and remember it's appropriate to always speak with the developer of a significant piece of work before reusing it!
PS. Reactions can be posted here.