The Joy of Licenses

[Helmut Enck-Radana]

In case anyone who needs to know about open source licensing issues isn't 
aware of the available resources:
There is an explanation of various license models from the view of the FSF 
on their site:
http://www.gnu.org/philosophy/license-list.html
And the natural language explanation of the EPL is here:
http://www.erlang.org/license/EPL1x0-explained.html

>The reason for this mail is that I've been thinking of writing glue code 
>to be able to use GSL (http://sources.redhat.com/gsl) from erlang. I 
>didn't get very far because of licensing issues.
>
>As far as I can tell, Erlang Public License (EPL) is based on Mozilla 
>(MPL) 1.0 which is incompatible with the GNU GPL, the license used by the 
>GSL people.
>I guess this means that if I ever get around to write glue code between 
>them, I wont be able to share this with anyone.
>
>My question is if I'm correct. If so, perhaps the EPL license could be 
>enhanced to make this possible.
>If I'm wrong, under what license should the glue code be published ?

If there was a problem, it could be solved by publishing Erlang under the 
GPL and the EPL as well. But I don't think there is a problem as long as 
you don't reuse and modify sources which are under the EPL. (That's my 
personal opinion, and I'm not a lawyer.)

If you have to reuse EPLed code, then there could be a problem. The EPL 
doesn't force you to publish your whole derived work under the EPL, only 
the reused EPLed code remains covered by the EPL. But the problem here is 
(as far as I can see) that any modifications of this code have to be 
reported to Ericsson, and you have to give credit to them (paragraph 3.3). 
The GPL on the other side forces you to apply the GPL to the whole derived 
work if you publish it, and requires you not to add any additional 
constraints on the reuse of the code. Possibly paragraph 4 of the EPL can 
be used to solve this conflict? (A clarification from Ericsson's side would 
be useful here.)

In fact there is already work which is based on code under the EPL and has 
been published under the GPL, e.g. http://www.idealx.org/prj/idx-xmnesia. I 
cannot imagine that it is intended by Ericsson or the FSF to prevent you 
from publishing your work. That would be contrary to the idea of Open 
Source, wouldn't it.

-- Helmut