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

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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 end state 

State machines often, but not always, have an **end state**. This is a state from which we can’t transition. In Islands, we have an end state called `:game_over`.

We won’t need any new `check/2` clauses for the `:game_over` state because there are no new actions to add to the whitelist. The catchall clause returns an error no matter what we try to do when the state is `:game_over`.

At this point, we can see our state machine make it through all the states and try all the events.

## New IEx session 

Let’s start a new IEx session, get a new `rules` struct, and make sure it’s in the `:initialized` state:


# The end state 

State machines often, but not always, have an **end state**. This is a state from which we can’t transition. In Islands, we have an end state called `:game_over`.

We won’t need any new `check/2` clauses for the `:game_over` state because there are no new actions to add to the whitelist. The catchall clause returns an error no matter what we try to do when the state is `:game_over`.

At this point, we can see our state machine make it through all the states and try all the events.

# New IEx session 

Let’s start a new IEx session, get a new `rules` struct, and make sure it’s in the `:initialized` state:


Understand the details of the Game Over module.

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

Game Over

The end state

New IEx session