I see that even a simple, but robust, implementaion covering each case (possibly some of them awaiting implementations of apropriate policy) would be hard, if not infeasible, to be done in such a short period of time as is given in GSoC. On the other hand I would take a deeper look in that topic and meanwhile look for another proposition. Many thanks for all your answers and clarifiyng all the infarmation and possible problems. Kamil Witecki.