We’ve covered software licenses a fair amount in our Software Process Management course. The MIT license, Apache License, and GNU GPL were the most notable for different reasons, but I figure that there are far more licenses that we haven’t necessarily gone over directly in class. I wanted to take the time to familiarize myself with some of these licenses.
Starting off with a CopyLeft license (a type of license I find myself fairly sympathetic to for the sake of keeping software open source), the Mozilla Public License, or MPL, is a weak sort of CopyLeft. According to this post on fossa.org, this means that users must disclose changes, but for a much narrower set of code for each change, file-based for short. When compared to the LGPL, a notable weak copyleft license, the MPL allows users to sublicense as an additional permission. Notable uses of this license are, of course, Firefox and Thunderbird, along with LibreOffice. I do like the idea of having a middle ground between being completely permissive and also wanting to “spread” open-source.
BSD Licenses are permissive licenses that generally have no restrictions. This license seems to fall in line with the big permissive licenses (like MIT) and doesn’t have a viral effect, but requires a copy of the license and a disclaimer of liability. According to a post on AppMaster, the differences between the MIT licenses and the BSD licenses is there being no requirement for a liability disclaimer for the MIT license, no requirement for patent protection on the BSD license, the BSD license being compatible with GPL, and the MIT license requiring a permission notice. I don’t like the lack of patent protection with this one, I know that’s been a fairly annoying issue in the past for various projects.
Lastly, I took a look into the OpenSSL license, as it was on the front page of tldrLegal. Funnily enough, it’s a license styled off of the BSD license, with the express purpose of being used with the OpenSSL project. On the aforementioned tldrLegal page for the license, it mentions in the summary that the license has a special advertising clause, which means that ads mentioning the software in any way must acknowledge the use of OpenSSL. The takeaway, for me, is that if you know exactly what you need with your license, and one that exists has everything you’d like except for one specific requirement or permission, you can build off of that license with that added requirement or permission (assuming that you have a legal expert of some sort write it, I’m assuming).
Overall, I really appreciate the work that has been done to ensure that we have a variety of different ways to license our software depending on what we want done with it. It’s definitely an important aspect of open-source development, and having the resources to find licenses that are closest to the project’s vision is an excellent way to focus on the development and not have to worry about the legal stuff.
From the blog CS@Worcester – V's CompSCi Blog by V and used with permission of the author. All other rights reserved by the author.