Hello all,
please let me introduce myself first. My name is Jan Wildeboer, I am member of the core team of a GPL'ed shopping cart solution, written in PHP, called osCommerce (www.oscommerce.com).
We just celebrated the second birthday of our project, we have the feeling we are quite successfull and we managed to build a community that supports our project.
Because we try to produce a global solution, we introduced a modules-structure for shipping and payment routines. We provide sample code and some global modules. Shipping and payment sometimes is very country-specific, so there are some country-specify mailing-lists/support sites that offer modules for these specific countries.
The way we understand the GNU General Public License all modules programmed to be used in our system must be published under the terms of the GPL. Our opinion is mainly based on this GPL-FAQ entry:
http://www.fsf.org/licenses/gpl-faq.html#GPLAndPlugins
This is due to the fact that shipping/payment modules use objects generated by our project (the cart object, customer address etc.). So we are quite sure that the second part of this FAQ-entry is valid in this context, so all modules written for our project MUST be published under the terms of the GPL or a GPL-compatible license.
Now we have one company that doesn't want to do this. They are selling modules under a closed-source license and they don't seem to be willing to accept our arguments.
I will provide more details if a serious discussion can be possible on this mailing list. From what I've seen in the last few days (The HURD vs. Schilling) I must wait for reactions :-)
Jan Wildeboer