Licensing Debate

Are the EPL and GNU Incompatible?

Jessica Thornsby

Mike Milinkovich’s tips on licensing open source software.

Mike Milinkovich has posted his thoughts on the compatibility of the Eclipse Public License (EPL) and the GNU General Public License (GPL) after Andrea Antonello submitted an open letter on the subject.

Andrea Antonello expressed some confusion regarding licensing in the open source community, and asked for some clarification on the GPL and EPL in particular.

In Milinkovich’s reply, he explains that these licenses are generally incompatible: “You may not link GPL and EPL code together and distribute the result. It doesn’t matter if the linking is dynamic, static or whatever.” However, there is still considerable grey area. If the EPL and GPL components interact with each other via pipes, sockets, or if Eclipse is running as an application on top of GNU Linux then, according to Milinkovich this is an entirely different scenario, which he does not discuss in his blog posting. There is also the possibility to create a combination of EPL and GPL plugins, which could not be lawfully distributed as a single unit. Milinkovich writes that it is not possible to link a plugin, licensed under the GPL, to an EPL-licensed code, and distribute the result.

Milinkovich urges Eclipse developers to use the EPL license for their Eclipse plugins, although if a developer creates an Eclipse plugin, they are not legally required to license it under the EPL.

Milinkovich concludes by pointing out that his blog post is intended for “general guidance” only. “This post was not prepared by an attorney nor is it in any way legal advice.”

Visitors to his blog have discussed the potential negative consequences of licensing open source software in general. One visitor points to a use case first raised by Antonello – distributing a GPL-bundle with the Equinox runtime – which Milinkovich implies isn’t possible. “This is really a huge and very negative implication,” the visitor writes.

“Just because something is open source does not mean that a developer can use it without regard to the license terms,” Milinkovich replies, highlighting the inherent conflict between the principles of open source software, and the reality of having to obey certain licensing terms.

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