by jerf | 2025-06-04 15:19:44+00:00
BEAM is basically the combination of a clustering system, a message bus for communicating among its nodes with a defined protocol, and a shared data model that can be thought of as basically "JSON, and only JSON, is the data model"; not JSON mapped into data structures or classes, but just JSON.

The biggest thing you need to have to have BEAM-like reliability is a message bus. Build a message-bus based system and use it properly and you're already 80% of the way there. In 1998, who knew what a "message bus" was? Today, it's a field so stuffed with options I won't even try to summarize them here. The one thing I will point out is that BEAM is 0-or-1 and 1-or-n seems to have won the race; this is one of the things I don't like about BEAM's message bus.

BEAM is based on a JSON-like data scheme because it wasn't clear how to have what you'd consider "classes" and such on a cluster with multiple versions of things any other way. Since then, there are now multiple technologies to solve this problem, like gRPC, Cap'n Proto, and again, what was "who's heard of that?" in 1998 is now an entire field of options I can barely summarize. It is no longer necessary to sacrifice everything we get with "methods" and "user data types" to have cross-cluster compatibility.

Bringing up clusters is now just Tuesday for a devops team. Kubernetes, Docker Cloud, all the cloud-specific orchestrations like CloudFormation, bringing up clusters of things now has many technologies you can deploy. Moreover, these technologies do not impose the requirement that your nodes be essentially homogeneous, all running BEAM. You can bring up any tech stack you like doing any specialized tech stuff you need, all communicating over shared message busses.

Reliability options vary widely, from running internal services in OS processes to capture and restart things, to things like lambda functions that are their own solution to that sort of reliability, to isolated micro-VMs, to threading-based solutions... while there is a certain appeal to "just crash and take the thread down" it's not the only option anymore. Now that every language community that can is building huge servers with millions of threads in them, many solutions to this problem have developed, with different cost/benefit tradeoffs for each. The "crash out the whole thread" is not the only option, merely one interesting one.

As to how they compare to BEAM, that does slant the question a little bit, as if BEAM is the golden standard that everyone else is still desperately aspiring to. How they compare to BEAM is that there is now a zoo of options of every sort, with a huge variety of tradeoffs in performance and cost and ease-of-use and ease-of-deployment, and BEAM is merely a particular point in the huge field now, which I wouldn't even characterize as particularly standing out on any front. For every thing it does like "have a nice crashing story" there's a tradeoff where it did things like "give up user-defined data types because they couldn't figure out how do to them in a cluster in the late 1990s". BEAM's feature set, on a feature-by-feature basis, isn't particularly special any more. There's faster options, there's easier options, there's "works with my current language" options, there's more reliable options, there's cheaper options, there's all kinds of things... but not all of these at once necessarily.

So, what is BEAM's unique value proposition in 2025? It is the integration of the solutions, and picking a set of solutions that IMHO may not be "the best" on any particular front any more but has proved to be "adequate to many tasks" for decades now. You can assemble all those technologies I mentioned in an incredible number of combinations, but you have to do the assembly yourself, and burn time asking yourself, which message bus? Which clustering? Which orchestration? It's overwhelming, and made even harder by the fact that even with all these choices there's still a lot of developers who don't even know these things exist, let alone how to evaluate them and start integrating them into a system successfully. BEAM offers a one-stop shop, with prepared and opinionated answers with a proved track record, and a community that knows how to use them, libraries that integrate with the opinionated answers. I.e. who can write a library that "works with Kafka, Amazon SQS, NATS, Redis streams, Postgres events, and a dozen other messaging libraries" without having to work with a lowest common denominator that is almost useless? But someone can definitely provide "an Erlang library" that meaningfully integrates with all of the BEAM infrastructure without an issue. I don't think BEAM is best-of-breed on any particular front but it is arguably best-of-breed in providing them an answer to you for all these problems under a single roof, and then being able to build on the advantage that picking a set of solutions brings you.

I wish the BEAM/Erlang/Elixir community would lean more into this as their pitch, and stop running around and acting like they've got the only solution to the problems and as if they are the gold standard. The advantage of BEAM is not that they have the only reliability solution, the only message bus, the only clustering solution, the only etc. etc. anymore... the advantage is in the integration. The individual components of the solutions are not where the awesomeness lies; in 2025 most of them have been handily exceeded on many fronts now, but that integration and the subsequent things like libraries built on that integration is a unique proposition, even today. The very explosion of choice in the solutions to the problems BEAM addresses and the resulting diaspora in all the code bases in the world make it difficult to build very much on top of these things because there's so many differences in so many places.