ZeroMQ – Relicense from LGPL3 and exceptions to MPL 2.0

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  • ZeroMQ

    ZeroMQ core engine in C++, implements ZMTP/3.1

    People contacted were people who made major modifications, not every single contributor. And yeah, if the contributor don't agree to the new license, you can either don't do the license change, or remove the code they wrote as they don't agree to the new license.

    There is more background here:

    Sometimes companies who do "FOSS" make you sign some sort of agreement that they own the code you produce and you won't have any say about re-licensing, so maybe the projects you're thinking about have done that?

  • OZ

    OpenMAMA/ZeroMQ bridge (by nyfix)

    Well, the original non-thread-safe sockets (e.g., ZMQ_SUB, etc.) were that way because they support multi-part messages. And yes, the fact that they are not thread-safe is a bit of a stumbling-block for ZeroMQ newbies (including me, back in the day).

    However, it's not that hard to work around their non-thread-safe nature with a single dispatch thread (e.g., see <>), and that approach has other potential benefits.

    In any case, newer socket types (e.g., ZMQ_CLIENT) have since been defined that are thread-safe, but necessarily don't support multi-part messages. (They tend to be different in other ways as well -- e.g., ZMQ_RADIO/ZMQ_DISH are "sort of" replacements for the original ZMQ_PUB/ZMQ_SUB sockets, but have other constraints as well).

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  • license-list-XML

    This is the repository for the master files that comprise the SPDX License List

    The LGPLv3 exception had an atypical feature (for *GPL exceptions) and was possibly misdrafted, see:

  • Bitcoin

    Bitcoin Core integration/staging tree

    Fun ZeroMQ fact: bitcoind has used zeromq since 2015. This is used by client software including lightning node daemons to get notification of incoming transactions and blocks in a highly reliable and rapid way.

NOTE: The number of mentions on this list indicates mentions on common posts plus user suggested alternatives. Hence, a higher number means a more popular project.

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