ghislainle

I do not remember all the details, but I think it was during the transition from MQTT 3.1 to 5.0. We only use 3.1 and the 5.0 code was not yet finished, emqtt had a hard coded a dependency with an old lib, which we wanted to upgrade. There were no hex package, it was pulled from github. And then the repo on github disappeared (or maybe moved?)

I will have a look at this new package, it looks promising

I want to add that the relay server is never handling any customer secrets (so a low value target), and we have techniques in place to reduce the probability of DoS (increase the cost to the attacker).

So even if someone would be able to break into the server through the small attack surface, he would not be able to change any setting on any of our customer's devices. Or even read any status either. Of course, if someone can break into our server, the DoS is inevitable, but so far this never happened.

One criticism I have with elixir is the lack of typing (they are working on it now, but I have yet to use it). So yes, I think gleam would be nice. But when we started, it was not even version 0.1 (and I had not heard of it)

I suppose we can have a mixed language project, with erlang, elixir and gleam. Not sure about the practicality of it though

We also use a fork of Tortoise, wrapped in some easier to integrate code (for our use case).

At first, we used an erlang lib emqtt, but it was left unmaintained and then removed from github. We had to switch to something else. Not completely happy, but it works for us

Main developer here.

We use MQTT a lot, it is really a central piece of our architecture, but Elixir brings a lot of benefits regarding the handling of many processes which are often loosely coupled. The BEAM and OTP offer a sane approach to concurrency and Elixir is a nice language on top. Here is what I find the most important benefits:

- good process isolation, even the heap is per process. This allows us to have robust and mature code running along more experimental features without the fear of everything going down. And you still have easy communication between processes

- supervision tree allows easy process management. I also created a special supervisor with different restart strategies. The language allows this and then, it integrates as any other supervisor. With network connections being broken and later reconnected, the resilience of our system is tested regularly, like a physical chaos monkey

- the immutability as implemented by the BEAM greatly simplifies how to write concurrent code. Inside a process, you don't need to worry about the data changing under you, no other process can change your state. So no more mutex/critical sections (or very little need). You can still have deadlock though, so it is not a silver bullet