I was looking at an open source VCL component that looks like it would be useful in some of my products. Then I noticed it came with a Attribution-Share Alike 3.0 Unported license. The sticky issue is (emphasis mine):
Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under the same, similar or a compatible license.
I don’t know the exact legal definition of “build upon”. Does using the component in my application constitute building upon the component? My opinion is that it does. That would mean if I use the component in my application, I would have to release my whole application as open source under a creative commons compatible license. Right now, that means the creative commons license itself.
The full license agreement does not use the term “build upon”. It does state:
“Adaptation” means a work based upon the Work, or upon the Work and other pre-existing works, such as a translation, adaptation, derivative work, arrangement of music or other alterations of a literary or artistic work, or phonogram or performance and includes cinematographic adaptations or any other form in which the Work may be recast, transformed, or adapted including in any form recognizably derived from the original, except that a work that constitutes a Collection will not be considered an Adaptation for the purpose of this License. For the avoidance of doubt, where the Work is a musical work, performance or phonogram, the synchronization of the Work in timed-relation with a moving image (”synching”) will be considered an Adaptation for the purpose of this License.
The license does not talk about software at all. But it does explicitly consider adding somebody else’s music to your own video as creating an adaptation. Combining a musical component to create an audio-visual work seems rather similar to combining a software component to create a software application. If the analogy holds up, the software application would be an adaptation that must be licensed under a Share Alike license.
The correct interpretation of the license doesn’t really matter. It clearly does not explicitly permit using the software component in a closed-source application. Therefore, I will not risk using software components licensed under CC BY SA, just like I won’t use components licensed under the GPL. Respecting other people’s licenses is simply the right thing to do. In this case, for me that means not accepting the license and not using the software.
If you develop an open source software component, do your fellow developers a favor, and choose a license that’s specifically written to license software. If you like the Creative Commons logos, here are the licenses you can choose from:
CC GPL: The original copyleft license. This one explicitly requires anyone using your softwaer component to release the source to their whole application.
CC LGPL: Slightly relaxed copyleft license. This one explicitly permits anyone to use your software component without releasing the source to their application. Only changes to the component itself need to be released as open source.
BSD: The BSD license is a very liberal open source license. It allows your software component to be used and modified without requiring the source code to the modified component, or anything its used in, to be published.