Aspects of Developing With, and Using, Open Source Software
Before I actually talk about the actual licenses, I'd like to correct a common misconception. Just because you write a program based on open source code, you don't necessarily have to make the source code available. If the application is a personal one, or one that's just being used in your company, there is no requirement to make the source code public. The public source code requirement only cuts in if you make your application public - then you must also make the source code public. There are lots of different 'open source' licences, but they basically fall into two groups - GNU's General Public Licence (usually referred to as 'The GPL') and all the rest of the licences. The purpose of open source licensing is very simple. It is a way of making sure that once you have made source code available to the public, the rights and privileges you have given to its users cannot be taken away or diluted by other users. Some people refer to this 'copyleft'. The licences span a spectrum. At one end is the granddaddy of all the open source licences, the GPL. The GPL insists not only that the source code for the application you are releasing is open, and that anyone copying it must make the source available, but also that any code derived from yours must also use the GPL. As you move down the spectrum, the uses to which you may put the code become more restrictive, and/or the restrictions on what sort of licences you may use for derivative code become more relaxed. Don't take this issue lightly - the further away your licence is from the GPL, the less likely you are to be able to get people to work with you on your project. Licences are a source of serious - almost religious - fervour in the open source community. Oh, and one other thing, don't think you can 'take back' the code after you've released it, if for some reason the open source model doesn't work for you. It's been tried, and no one has yet succeeded, though the people who tried it made plenty of enemies for life! Once you commit your project to open source, it stays there until the end of its lifetime (which is actually likely to be longer than if it is proprietary). There is a good summary of the effects of the main open source licences (albeit from GNU's point of view) on the GNU web site - http://www.gnu.org/philosophy/license-list.html. |
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