Gain insights into building scalable backend applications with Elixir, OTP, and Phoenix. Learn about persistent connections via Phoenix Channels, and explore distinct, decoupled application layers.

Functional Web Development with  Elixir, OTP and Phoenix by The Pragmatic Programmer_ .png

elixir_islands_test.tar.gz

elixir-app

pheonix-app

elixir-app-guesses

island-interface

phoenix-app-compiled

phoenix-app-iex

phoenix-app-form

phoenix-app-new-module

client-connection

presence

phoenix-app-final

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Elixir and OTP provide exceptional tools to build rock-solid backend applications that scale. In this course, you’ll build a web application in a radically different way, with a backend that holds application state. You’ll use persistent Phoenix Channel connections instead of HTTP’s request-response, and create the full application in distinct, decoupled layers.

In Part 1, you’ll start by building the business logic as a separate application, without Phoenix. You’ll model the application domain with Elixir functions and simple data structures.

In Part 2, you’ll add in the GenServer Behaviour to make managing in-memory state a breeze. 

In Part 3, you’ll build a web interface with Phoenix where you’ll use Phoenix Channels to establish persistent connections between the stateful server and a stateful front-end client.

Needless to say, you’re going to love this way of building web apps!

Functional Web Development with Elixir, OTP and Phoenix

The simplest thing we can do with a `GenServer` is spawn a new server process and send it a message. We’ve just learned to spawn a new game server process and bind the resulting PID to a variable. Once we have that PID, we can use `Kernel.send/2` to send it a message. Once we have the message passing down, we can customize behavior based on that message.

# New IEx session

Let’s see how this all works.

In a new IEx session, let’s start a new game process and send it the `:first` message:
``` IEx
alias IslandsEngine.Game
{:ok, game} = GenServer.start_link(Game, %{}, [])
send(game, :first)
```
As we can see, this works somewhat. At least it doesn't crash the IEx process.

>**Note:** Run these commands below. We can either get the `[error]` or the `[warn]` message. We should press any key if we don't see `iex>` in the terminal.


Learn how to initialize GenServers with the correct state.

Introduction

Mapping Our Route

Model Data and Behavior

Working of State Machines

Add OTP for Concurrency and Fault Tolerance

Process Supervision for Recovery

Generate a New Web Interface with Phoenix

Create Persistent Connections with Phoenix Channels

Appendix

Passing Messages

New IEx session