Establishing Our Boundaries

Boundary layer

The boundary layer deals with side effects and state. This layer is where we’ll deal with processes and where we’ll present our API to the outside world. In Elixir, that means OTP. To be more precise, the boundary layer provides the following functionality:

• The machinery of processes, message passing, and recursion, which form the heart of concurrency in Elixir systems.

• An API of simple functions that hide that machinery from clients.

Getting started

We typically call the collective machinery a server, the code that calls that server an API, and the code that calls that API a client. In OTP’s case, the server in that ...