[asabil]

`gen_server` is an abstraction over the a client sending a `request` that a server services to produce a `response` to be sent to the client.

The `gen_server` implementation takes care of things like timeouts, servers terminating before a response is produced as well as maintaining the server state.

You can read more here at [1], [2] and [3].

[1]: https://learnyousomeerlang.com/clients-and-servers#callback-...

[2]: https://www.erlang.org/doc/system/gen_server_concepts

[3]: https://www.erlang.org/doc/apps/stdlib/gen_server.html

[vector_spaces]

I'll add to this that the "abstraction" component of this description is key and the use-case for a gen_server is far more broad than what you might expect in say a networking or web context.

You would use them for instance when you need to group behavioral units with a defined interface, even if you don't require any explicit networking.

This is a bit reductive and wrong in some ways but think of gen_server modules and instances as "sort of" like classes/objects. You "send messages/requests" instead of "calling methods," but the spirit is essentially the same -- it's a way of modeling the world with code

[igouy]

"Computing should be viewed as an intrinsic capability of objects that can be uniformly invoked by sending messages." p 290

1981 "Design Principles Behind Smalltalk"

https://archive.org/details/byte-magazine-1981-08/page/n298/...

[skeledrew]

> You "send messages/requests" instead of "calling methods,"

Sounds like Smalltalk.