Otp application and libraries discussion

Chat / Discussions
, ,
1

So I’ve written an article discussing the difference between “applications” and “libraries” as OTP applications.
I’ve tried to differentiate between them in the context of OTP, and I’d like to know what people think about the points that I made on it.

2

The difference is similar as in OS libraries vs applications (in context of system supervisor). Library is just set of functions grouped in the modules where application is something that can run on its own. Good example there can be OpenTelemetry API vs OpenTelemetry SDK where the first one is “library of functions” and second one is “independent application with own supervision tree”.

1 Like
3

I understand the difference between them. My point on the article is that creating an “application” is an anti-pattern from the point of view of OTP that should be avoided because it reduces the control we have over the execution and how other parts of the system interact with it.

4

Yes, because 95% of the time when someone defines application, they wanted library instead. You rarely need to write full application for your purposes, in most cases exposing functions that spawn processes you need is much better than spawning that function for the user, but still there are use cases when it is desirable. For user convenience (like in my systemd library) or that we just need a mutable state for keeping info about rest of the system (like in telemetry, however I think that in future persistent_term may be used there) or that there is no reason for having multiple instances of the processes as it is “sidecar-like” application (like OpenTelemetry).

5

FYI, the article is not available anymore. In fact cevado.me is “available on GoDaddy Auctions”.

Interesting article about it at Reusable Elixir Libraries.

1 Like
6

i’ve moved it to https://cevado.wtf/
i’ll make that post available again and link it here.

edit:
so a link to the original blog post of this topic

keep in mind that the tone that i’m using this blogpost is not a good one, very mandatory and shitting on peoples solutions. i was planning to rewrite it with a better tone and better language, but never had the time.

2 Likes