OpenFOAM is Free Software | CFD DirectOpenFOAM is free software. By free, we mean that users have the freedom to run, copy, distribute, study, change and improve the software.  Users undoubtedly benefit from these freedoms, which account for much of OpenFOAM’s popularity.  Being open source is a precondition for some of these freedoms, such as allowing study and change of the software and redistribution of modified software.  The General Public Licence (GPL), under which OpenFOAM is licensed, is designed to preserve the freedoms by granting rights under certain conditions, notably that:

  • all distributed copies (modified or not) carry a correct copyright notice and retain the licence and warranty notices;
  • all modified copies are distributed only under the GPL with no further restrictions;
  • all compiled versions of the program are accompanied by the relevant source code, or a viable offer to obtain the source code, usually by download from a network server.

Preserving Software Freedoms

There may be parties who directly seek to bypass the terms of the GPL in an attempt to deny the freedoms under which the contributors to OpenFOAM released their work.  If this happens, it is the licensor of the software that must enforce the licence to preserve the freedoms granted by the contributors, taking legal action if necessary.  The licensor is the entity or entities who owns the rights to the software through the copyright in the source code (unless rights have been specifically been granted otherwise).  In the first instance, the copyright belongs to the individual contributor or their employer (depending on employment contract, jurisdiction, etc).  Sometimes an individual is willing to take legal action, most recently a Linux kernel developer, Christophe Hellwig against VMware, with strong support from the Software Freedom Conservancy.  But most individuals and their employers would not be willing to engage in licence enforcement.  Furthermore, where the software is owned by multiple parties, legal action depends on the cooperation between all copyright holders, which is why the Free Software Foundation (FSF), who created the GPL, insists on copyright assignment from contributors to their software projects “in order to be able to enforce the GPL most effectively”.

The OpenFOAM Foundation

Freedoms are potentially undermined when free software has multiple owners.  For OpenFOAM, our position is that the enforcement of the GPL should be the responsibility of one organisation dedicated to that purpose, rather than the job of individual contributors and/or their respective employers.  That is why in 2011 we (Henry Weller and Chris Greenshields)  founded the OpenFOAM Foundation to take over responsibility for OpenFOAM and its distribution to the public exclusively as free software.  Like the FSF, the OpenFOAM Foundation holds the copyright to the entire OpenFOAM code it distributes, and has a governance structure specifically designed to ensure OpenFOAM remains exclusively free software forever.  It works closely with a leading lawyer in computing and information technology with specific expertise in free software and its members from CFD Direct provide extensive experience in the business and management of free software.  Together we created the OpenFOAM Contributor Agreement for individuals and corporate entities to assign copyright in their OpenFOAM contributions to the Foundation (or grant the Foundation a very broad licence in the contribution, for countries whose laws do not make assignment possible).  The Agreement includes an unequivocal statement that their contribution will be licensed by the Foundation only under the terms of the GPL, and the Foundation immediately grants back a licence to them to use their contribution, so the Foundation cannot somehow prevent its distribution.

The Community

Anyone who contributes to OpenFOAM must sign the OpenFOAM Contributor Agreement.  The agreement can be signed by: an individual, which generally requires the consent of the organisation that employs them; or by the organisation itself, which then covers contributions from others in that organisation.  Those with a serious commitment to OpenFOAM and software freedom accept this: in the first 6 months since its creation, it was signed by 6 organisations, including us (CFD Direct), blueCAPE, VTT Technical Research of Finland Ltd and Intel, and by 8 individuals.  These contributors are at the heart of a growing community around OpenFOAM that brings together individuals who want to contribute to free software.  It is a community in the true sense — a group with shared attitudes and common interests — working collaboratively on the public development repository of OpenFOAM.  It is this community of individuals that works tirelessly to preserve the freedoms enjoyed by OpenFOAM users, supporting one organisation dedicated to licence enforcement that is in the strongest position possible to enforce the licence through single ownership.  If you appreciate these freedoms, you can help by becoming part of the community, e.g. by questioning the motives of organisations that take an irresponsible attitude to copyright when releasing modified versions of OpenFOAM and by promoting the Contributor Agreement within your organisation.  For more information or to get involved, please contact the OpenFOAM Foundation.

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