Earlier today, Julian Buss released a new project on OpenNTF called YouAtNotes xCharting under the GPL license. I have absolutely no problem with his license choice, I fought hard to have the GPL license be a valid license type on OpenNTF so that some people, like Julian, can select it for their projects.
But it is important to know WHY your selecting the GPL license and what it means, basically the GPL license allows you to use the code in any of your own applications, however as soon as the GPL code goes into your application you application must then be licensed as GPL and the source code needs to be made available on request or be freely available online.
You might argue that your only going to use it in an internal application for your company, but the license still applies, your internal application and all the code it contains must now be licensed with the GPL license. If somebody, anybody, asks for the source then it must be supplied or your breaking the law. In 2006 D-Link were successfully sued because they used GPL code in their routers without releasing the source code and that is just one of many cases. If YouAtNotes use the xCharting code from OpenNTF in their commercial products then their commercial products are now GPL and anybody can request the source code for the ENTIRE product.
Even worse is mixing your licenses, and I’ll take an OpenNTF project as an example. The Bildr project by Patrick Kwintensson in it’s current V3.0 release is licensed as APLv2 however it contains a file upload control call PLUpload that is licensed as GPLv2. What this means is that Bildr is incorrectly licensed, it is not possible for it to be licensed as APL because of the GPL code in it. The OpenNTF IP Manager is aware of this and the project is in danger of being shut down if the license is not corrected soon. Of course the Bildr project also contains other code from other sources so simply changing Bildr to GPL won’t be sufficient.
The point that i’m trying to make is that you DO need to be careful about the licenses that you use for your open source projects and you also need to make sure that all code that you source from other places has a correct license. I looked at Bildr because of the file upload control, i was thinking it would fit in very well for another application that I’m writing and seeing the APL license on Bildr I would have thought I was in the clear, it wasn’t till I went to the PLUpload website that I found it was actually GPL.
So if your going to release stuff as GPL be aware that it is a restrictive license, while it does encourage sharing it can also stop people from using the code and in some cases, from even being allowed to look at the code.