On 02/06/2011 18:19, Maksim Konovalov wrote:


Our company is currently developing an open source software product named RadixWare which is planned to be released under GNU General Public License (GPL) v3.0 due to a number of components licensed under GPL. The program comprises different open source components and unmodified Saxon HE is deemed to be one of them.

However, the FSF claims that the MPL and GPL are incompatible and therefore use of Saxon licensed under MPL in the GPL licensed larger work will be illegal from FSF’s point of view. On the contrary, MPL permits further distribution of unmodified Saxon under GPL license.

Would you be able please to advise how this incompatibility problem can be avoided or circumvented so that Saxon can be used in the larger work licensed under GPLv3.0? I believe this situation is nothing new to the Saxon community and probably one have an idea how to settle this issue or at least reduce the risk of legal persecution.

Thank you very much for your time, any help will be highly appreciated.


I cannot give you legal advice on this. I can suggest that the more lawyers you ask, the more conflicting advice you will get.

The argument that MPL and GPL are incompatible seems to be well summarized at


and it's worth reading the detail.

I'm far from convinced by it: it all hinges on whether an application that uses an XSLT processor can be considered part of "the same work" as the XSLT processor itself. Is that the case when you call JAXP interfaces without knowing which XSLT processor will be found on the classpath? Is it the case when they run on separate machines, were installed separately, and have no knowledge of each other's existence? So as far as I'm concerned, the way to "avoid or circumvent" the problem is to do whatever you consider necessary to demonstrate that your application and Saxon are not part of the same work; for example, you might consider it sufficient to demonstrate that your application can be used with any JAXP implementation, or that the choice of XSLT processor is made by the user, not by you.

Some products get around this problem by dual licensing. I'm not in a position to do that with Saxon because a change in license would require the permission of all historic contributors, and they aren't all traceable. In any case, I just don't like GPL: I hate its hectoring tone, its preaching of freedom in the preamble followed by removal of your freedom when it comes to the actual rules.

It might be worth noting that no-one is likely to sue you. Your difficulties won't come from being sued by the people who wrote the open source code you are using, they will come from corporations whose lawyers advise their clients against using your product. Lawyers are paid to raise difficulties: they earn their money from it, not from saying "go ahead, don't worry about it". Whatever you do, some of your potential users will raise objections. I've always found it a strange feature of the open source world that all the licensing difficulties come from users determined to look a gift horse in the mouth, not from the people who provided the creative input.

Michael Kay