[zeromq-dev] License Compatibility Question

Matt Shaver matt at mattshaver.com
Sat Mar 9 02:02:40 CET 2013

Some of the programmers of the linuxcnc project
(http://www.linuxcnc.org) are interested in replacing our current
messaging system, CMS/NML
(http://www.isd.mel.nist.gov/projects/rcslib/) with zeromq.

The programmers are very enthused about this, but questions have arisen
regarding the license compatibility between your LGPLv3 licensing, and
our "GPLv2 only" (plus some Public Domain) licensing.

Your licensing page (http://www.zeromq.org/area:licensing) and FAQ
page (http://www.zeromq.org/area:faq#toc0) lead me to believe that the
use of zeromq by our project would be allowable. However, one of our
people contacted one of your people, and he (our guy) says:

"I have asked the ZeroMQ steward, Pieter Hintjens, wrt to compatibility
of a GPL2only project and ZMQ, and his answer was a straight 'no'.
Maybe I didnt ask the right question, this is for sure worthwhile
following up with Pieter in more detail."

To be perfectly clear, we _do not_ intend to derive or create a new
messaging system by combining zeromq code with our code, we only wish
to use zeromq as a replacement for our current message passing
mechanism. Should we make any bug fixes, or add a new feature to zeromq,
we would contribute them back upstream under the terms of your LGPLv3

So, are we allowed to use zeromq in this way?

Matt Shaver

More information about the zeromq-dev mailing list