ZeroMQ and Crossroads I/O: Forking over trademarks

Trademarks and free software projects have something of a troubled history. On one hand, a trademark can protect the project from others using the name but offering sub-standard—or malicious—versions of the software. On the other, whoever holds the trademark also holds much of the power over the project as a whole. That can lead to conflicts, which is what we are seeing in a recent fork of the ZeroMQ (aka 0MQ or ØMQ) project.

ZeroMQ is a high-performance asynchronous messaging system that is based on BSD sockets. Two of the developers working on the project, Martin Sustrik and Martin Lucina, wrote about ZeroMQ for LWN in January 2010. Sustrik is the chief architect of ZeroMQ and, up until recently, served as the de facto "benevolent dictator" for the project, while Lucina has been working on the project since late 2009. On March 15, the two of them announced a fork of the LGPLv3-licensed ZeroMQ code as Crossroads I/O version 1.0.0.

The ZeroMQ trademarks

There were two main reasons cited for the fork in that announcement, but based on an email exchange with Sustrik and Lucina, the trademark issue is clearly paramount, at least for Sustrik. The trademark is held by iMatix Corporation which funded the early development of ZeroMQ. That trademark is governed by policy that essentially gives iMatix full control over how the names (ZeroMQ, 0MQ, ØMQ, and zmq) can be used.

That worries Sustrik for a couple of reasons. He believes that the underlying protocols for ZeroMQ should be standardized via the Internet Engineering Task Force (IETF), but that is not something that is easily done using volunteers:

His solution to the funding problem is to allow companies to make money by releasing modified versions, plugins, and extensions that can use the ZeroMQ name, which is something he says the current policy does not allow:

Given that trademarks are at the center of the disagreement, it is ironic that the trademark policy was created at Sustrik's request in May 2011. In a message on the zeromq-dev mailing list, iMatix CEO Pieter Hintjens noted that he created a policy and asked for feedback. There were no major complaints about the policy in that thread, but a suggestion from Sustrik that the trademarks be handed to a foundation (like Software in the Public Interest, which holds the Debian trademark) was not something that Hintjens was interested in:

But Sustrik is concerned that some day the trademarks could fall into "hostile" hands, which could essentially take control of various ZeroMQ-related projects (like the language bindings for roughly 30 languages) by asserting a different trademark policy. That also may make it difficult for ZeroMQ to attract companies to work on the project: "If I was a commercial entity I would be hesitant about investing in such a project". One of the early goals for Crossroads I/O is to find a "neutral entity" to control the trademark by the end of 2012. Until then, the policy states: "'Crossroads I/O' is trademark of Martin Sustrik. Martin Sustrik grants everyone the right to use the trademark with products related to Crossroads I/O (packages, plugins, extensions, tools and similar)."

Development process changes

Since a trademark owner can decide what gets to be called "ZeroMQ", it can also make fairly sweeping decisions about how the project is governed and released. According to Sustrik, after the 3.1.0 beta release, he was "explicitly prohibited to use [the] ZeroMQ trademark, which gives me no other chance than to fork". That prohibition came in a private message from Hintjens, he said. Around the same time, Hintjens posted a proposal for maintenance of libzmq (the heart of ZeroMQ) that makes no mention of a single maintainer, which is the role that Sustrik thought he had been filling.

In a Google+ posting (which Lucina called an "objective writeup"), Ian Barber pointed to a problem that may have been part of what led to the new development process: "Martin Sustrik was effectively a bottleneck for getting improvements into core, and was clearly being pulled multiple directions on features and functionality in the project".

As might be guessed, Hintjens has a somewhat different view from that of Sustrik and Lucina. In an email exchange, he noted that Sustrik was "in danger of burning out", which is part of what led to the changes. In addition, he doesn't see the trademark policy as a problem:

According to Hintjens, Sustrik and Lucina "happily ignored about a year of consensus on process, and unilaterally decided to take back control over stable releases" when they made the 3.1 release. That didn't sit well with some of the other contributors to ZeroMQ, which is what led to codifying the process and, ultimately, the fork.

The new process (scroll down to "Contributing to libzmq") is more wide open than that of most free software development projects. Anyone can fork the Github repository, make changes, and request a pull into the mainline. The maintainers are only meant to enforce process, ensure that the test cases pass, and are not allowed to impose their opinions on the quality of the code or feature. If others in the community are not happy with a particular patch, they are supposed to make another patch that fixes or reverts it—the maintainers are just there to apply it. The underlying assumption is that the community members will find and fix problems quickly by getting those changes in front of them sooner.

Barber calls the process "incredibly open", in fact, more open than he is comfortable with, but it has worked well so far:

Crossroads I/O is going to use the more common "benevolent dictator" model, with Sustrik in that role. Barber says that makes sense, because it is a proven model for open source development, but he is concerned that Crossroads will hit the same problems that ZeroMQ ran into. He also notes that while Sustrik and Lucina have both contributed a great deal to ZeroMQ, they are far from the only contributors to the project. It's not clear, at least yet, if others from ZeroMQ will start working on Crossroads I/O, nor whether the language binding authors will support both projects. That leaves users in a bit of a quandary, he said.

In any case, the new process installed by Hintjens is something of an experiment: "We will try it for a while and if it proves broken, we will fix the breakage and continue to improve it." But that experiment, coupled with what Sustrik sees as a restrictive trademark policy, is enough to cause the fork. What remains to be seen is if Sustrik and Lucina can build enough of a community to continue with their plans.

It is, at least in some sense, a friendly fork. Hintjens greeted the Crossroads I/O announcement with: "Congratulations on this, guys. It's nice to see the LGPL in action." Based on the emails from Hintjens, Sustrik, and Lucina, there was certainly some initial hostility and hurt feelings because of the fork, but, in the end, both sides seem to wish the other well. The two code bases share the same license, so there is no reason that patches cannot flow between them.

Hintjens noted that some may criticize the fork because it will split the community, but he strongly defended Crossroads I/O for a number of reasons. For one, he sees it as a place to do more experimental work, while ZeroMQ focuses on stability. He is also interested in seeing which of the two development models works out better over the long run. It will also provide a choice of free solutions for users, he said.

This fork, like most, comes out of a difference in philosophies between two sub-groups of the project. Unlike other forks, though, it doesn't come about because of license disagreements. It is interesting for another reason, however, as it serves as a reminder that a trademark holder can exercise a great deal of control over a project. Since the owner of the trademark can effectively decide what gets to be called by that name, they can override the wishes of longtime developers.

From all appearances, much of the ZeroMQ community is not upset with the changes or the fork. But most also seem to be keeping an eye on what Crossroads I/O is up to. If Sustrik and Lucina can make the benevolent dictator model produce a better messaging library than the more open ZeroMQ model does, there may be a shift toward Crossroads. By taking the trademark question off the table with a more liberal policy, Crossroads may attract some of the companies that Sustrik worries are put off by the ZeroMQ policy. That remains to be seen, of course, but what we do see is yet another example of the problems inherent in the coexistence of trademarks and free software.