The Single Vendor Model

When you take a project like Sentry, which started as an Open Source project and later turned into a VC funded company, its model revolves around a commercial entity being in charge. That model is often referred to as “single vendor.” This is also the case with companies like Clickhouse Inc. or Elastic and their respective projects.

Sentry today is no longer Open Source, it's Fair Source (FSL licensed). Elastic on the other hand is indeed unquestionable Open Source (AGPL among others). What both projects have in common is that they value brand (including trademarks), that they have strong opinions on how that project should be run, and they use a CLA to give themselves the right to re-licenses it under other terms.

In a "single vendor" setup, the company behind the project holds significant power (for ~150 years give or take).

The Illusion of Equality

When you look at the AGPL as a license it's easy to imagine that everybody is equal. Every contributor to a project agrees with the underlying license assumptions of the AGPL and acts accordingly. However, in practice, things are more complicated — especially when it comes to commercial usage. Many legal departments are wary of the AGPL and the broader GPL family of licenses. Some challenges are also inherent to the licenses such as not being able to publish *GPL code to the app store.

You can see this also with Elasticsearch. The code is not just AGPL licensed, you can also retrieve it under the ELv2 and SSPL licensing terms. Something that Elastic can do due to the CLAs in place.

Compare this to Linux, which is licensed under GPLv2 with a syscall exception. This very specific license was chosen by Linus Torvalds to ensure the project's continued success while keeping it truly open. In Linux' case, no single entity has more rights than anyone else. There is not even a realistic option to relicense to a newer version of the GPL.

The FSL explicitly recognizes the reality that the single vendor holds significant power but balances it by ensuring that this power diminishes over time. This idea can also be found in copyright law, where a creator's work eventually enters the public domain. A key difference with software though is that it continuously evolves, making it hard to pinpoint when it might eventually become public domain as thousands of people contribute to it.

The FSL is much more aggressive in that aspect. If we run Sentry into the ground and the business fails, within two years, anyone can pick up the pieces and revive it like a Phoenix from the ashes. This isn't just hypothetical. Bryan Cantrill recently mentioned the desire of Oxide forking CockroachDB once its BUSL change date kicks in. While that day hasn't come yet, it's a real possibility.

Dying Companies

Let's face it: companies fail. I have no intentions for Sentry to be one of them, but you never know. Companies also don't just die just once, they can do so repeatedly. Xapian is an example I like to quote here. It started out as a GPL v2+ licensed search project called Muscat which was built at Cambridge. After several commercial acquisitions and transitions, the project eventually became closed source (which was possible because the creators held the copyright). Some of the original creators together with the community forked the last GPLv2 version into a project that eventually became known as Xapian.

What's the catch? The catch is that the only people who could license it more liberally than GPLv2 are long gone from the project. Xapian refers to its current license “a historical accident”. The license choice causes some challenges specifically to how Xapian is embedded. There are three remaining entities that would need to agree to the relicensing. From my understanding none of those entities commercially use Xapian's original code today but also have no interest in actually supporting a potential relicensing.

Unlike trademark law which has a concept of abandonment, the copyright situation is stricter. It would take two lifetimes for Xapian to enter the public domain and at that point it will be probably be mostly for archival purposes.

Equal Grounds Now or Later

If Xapian's original code would have been FSL licensed, it would have been Apache 2.0 (or MIT with the alternative model) many times over. You don't need to hope that the original license holder still cares, by the time you get hold of the source code, you already have an irrevocable promise that it will eventually turn into Apache 2.0 (or MIT with the alternative license choice) which is about as non-strings attached as it can get.

So in some ways a comparison is “AGPL now and forever” vs “FSL now, Apache 2.0/MIT in two years”.

That's not to say that AGPL (or SSPL) don't have their merits. Xapian as much as it might suffer from their accidental license choice also is a successful Open Source project that helped a lot of developers out there. Maybe the license did in fact work out well for them, and because everybody is in the same boat it also has created a community of equals.

I do believe however it's important to recognize that “single-vendor AGPL with a CLA” is absolutely not the same as “community driven AGPL project without the CLA”.

The title claims that FSL balances Open Source better than AGPL, and it's fair to question how a license that isn't Open Source can achieve that. The key lies in understanding that Fair Source is built on the concept of delayed Open Source. Yes, there's a waiting period, but it’s a relatively short one: just two years. Count to two and the code transitions to full, unshackled openness. And that transition to Open Source is a promise that can't be taken from you.