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Comment by jameskilton | Hacker News Reader

So I can't find the reason why this project exists instead of just contributing to 0MQ directly.

From the web site (http://www.crossroads.io/faq):

```Why was Crossroads I/O forked from ZeroMQ?

The contribution and trademark policies of the ZeroMQ project were, as of March 2012, incompatible with our long-term goals.

Who is behind the fork?

The main work on the fork was done by two of the original developers of ZeroMQ, Martin Sustrik and Martin Lucina, with help and advice from other members of the ZeroMQ community.'''

I've read it, and yet not understood which are those incompatibilities in the goals

"To grow such an ecosystem the project must be fully vendor neutral, and implement a liberal (e.g. Linux-style) trademark policy allowing use of the trademark for third party distributions of the software, as well as for plug-ins and extensions."

Ah, a Centos/Red Hat thing.

As I understand it (as a regular on the ZeroMQ and Crossroads mailing lists), the reasons are as follows:

1) Trademark issues - the original developers of ZMQ have been prohibited from using the ZeroMQ trademark and, thus, from making official releases.

2) The new ZeroMQ contribution policy[1], in which pull requests are merged without review and then later reverted/enhanced if necessary, is seen as incompatible with the goals of some of the lead developers. These developers prefer a more rigorous review policy.

There are more reasons, but from what I can tell, those are the main ones that haven't fully been covered here.

[1]: http://www.zeromq.org/docs:contributing (see "Philosophy").

If you want more background to what led up to our fork of ZeroMQ, read the flamewar on zeromq-dev from February carefully hidden in a "C++ assertion" thread at http://lists.zeromq.org/pipermail/zeromq-dev/2012-February/0..., or from http://lists.zeromq.org/pipermail/zeromq-dev/2012-February/0... which relates directly to the trademark question.

I noticed there's a compatibility library with 0mq. What are the technical changes that require a compatibility library?

This seems to imply there are API differences, rather than just the same code with different development policies going forward.

The compatibility configure flag seems to be used to also install the crossroads library as libzmq.so.

I'd say “personal differences” (regardless of the deal about trademarks and code review), but it still surprises me; I thought the zmq developers were a tight-knit bunch. Maybe the drama manifests itself in more extreme ways because they know each other so well, but it does seem dysfunctional.

I agree with you. When you fork a project, there better be a good reason. And when there is a good reason, there's no reason to be vague in the explanation. (and I can't think of a vaguer explanation than what they write)

Giving an example of a problem solved by the fork would help, though I'm not sure a solid example of a goal not possible within 0mq can be found based on the project goals.

Looks like a move from GPL to LGPL.

I had assumed that zmq was BSD licensed to begin with - so I've learned something.

That can't be it, as 0mq is also LGPL. From the footer of zeromq.org:

   ØMQ is free software licensed under the LGPL

And in every source file:

   0MQ is free software; you can redistribute it and/or modify it under
   the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

As I have some investment in the 0mq ecosystem, it would be nice to know what this means in the long run for that project.

According to [1] ZeroMQ is licensed under LGPL with static linking exception.

[1] http://www.zeromq.org/area:licensing

You can't do that without the consent of every contributor. At least not legally.

Not exactly. The zmq library is already LGPL. It's the plugins and examples that are GPL. That might be a potential reason crossroads I/O was created -- to start an ecosystem of plugins that are LGPL too.

source: http://www.zeromq.org/area:licensing

I think this email from the guy in charge of 0MQ now is fairly clear: http://lists.zeromq.org/pipermail/zeromq-dev/2012-February/0...

On a related note, developers can be mean

from reading the email thread it appears this is the main issue:

zeromq is looser about what ends up in master. They view master as sort of a global staging area, and what ends up in release branches is viewed as stable/vetted code. As a result, master can be quite unstable.

The people that forked wanted a more stable master, with lots of code reviews before patches end up in master.

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