Wednesday, 26 March 2014

Apache to the rescue



The announcement of an American competition for an open source hydrodynamic solver posed a conundrum for a French research laboratory with their own in-house hydrodynamic code. The LHEEA lab at École Centrale de Nantes (ECN) had been thinking of open-sourcing their code Nemoh for some time. Submitting Nemoh to NREL's OpenWARP competition would make it available to a wide audience, but this would come at a cost: ECN would effectively loose authorship of the code. It was decided to make Nemoh open source first, and then to submit it to OpenWARP.

This idea posed a couple of problems for NREL. Firstly, with Nemoh open source, any old cowboy could submit Nemoh as an entry to OpenWARP. Secondly, the type of open source licence that ECN had planned to attach to Nemoh was problematic.



Apache vs General


Initially the intention had been to use the GNU General Public Licence (GPL). This is the most popular open source licence. It is a Copyleft licence: any GPL code is freely available for use and modification, but all modifications must inherit the licence. This is the most right-on open source licence, so what's the problem?

Many private companies are wary of the GPL because it comes with strings attached: it is a contagious licence. Any modifications made to GPL code and shared with collaborators must also be made available to the community at large. As private companies need to protect their IP, they are often hesitant to contribute to GPL code projects. Academic institutions that are interested in developing spin-out companies from research may also have policies not to incorporate GPL code into new software, so as to avoid unpleasant surprises for future spin-out companies
 
The Apache 2.0 licence is open source with no strings attached. It is much more permissive: modifications of this code are not automatically open source, and authors of code improvements can decide how their contributions will be licenced and shared. NREL and TopCoder (the on-line platform hosting the OpenWARP competition)  have a strong preference for the Apache 2.0 licence for these reasons.


Nemoh as a core for OpenWARP


Discussions between NREL and ECN about submission of Nemoh to OpenWARP resulted in a new plan. ECN agreed to licence Nemoh under Apache. NREL have agreed to raise the bar on the OpenWARP competition: the winning entry should have at least Nemoh's functionality, and then some more.

With Nemoh now open source, there is the opportunity for entries to OpenWARP to be based on Nemoh. The Nemoh code can be downloaded from: http://lheea.ec-nantes.fr/doku.php/emo/nemoh/start?&#nemoh


Image credits:

Pilgrim humour by Duckshow: http://duckshow.com/2011/11/pilgrim-humor.html
Copyleft logo: http://en.wikipedia.org/wiki/Copyleft

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