AGPL Question about Linking and Derivative Works

Question

I'm thinking of selling a collection of Django apps I've written which provide the basic functionality of a Facebook game, but I'm also thinking of releasing it under a GNU Affero GPL.

I read the Affero GPL, and the extra clause specified that modified versions of a covered work have to be distributed under the same license. What I'm wondering is, do derivative works have to be distributed under the GNU Affero License, even if they don't modify the original? The scenario is someone could use my project and add a few features of their own contained in separate Django apps; would those new apps they've written which depend on my software have to be released under an Affero license as well?

Answer 1

Usually the derivatives must also be licensed under the AGPL too, but there's some room for debate on what is considered a derived work. If a work acts as a separate service which the AGPL code communicates with (not sharing a process address space), and such service could be reasonably replaced with an alternative, then it could perhaps be considered a new work rather than a derived one. Most django "apps" are combined works though - they share the same process space, which is what the GPL licenses consider to be combined work.

Answer 2

Any work containing sufficient protectable expression from code covered by the AGPL (that is, a derivative work) must have its source code released if it is distributed. Such a work is a "work based on the Program".