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 strategies describe a lot of how a supervisor works with child processes, but they are not the whole story. There are a number of other options we can specify. Those options are stored in the child specification.

Fortunately, we don’t have too much work to do here. The `GenServer` Behaviour creates a default child specification for us whenever we add the `use GenServer` line to a module.

# New IEx session

We can check the child spec for the `Game` module in IEx with `child_spec/1`, and pass it the argument we want the supervisor to use as it starts a game.

> **Note:** Run these commands in the terminal below:
```IEx
alias IslandsEngine.Game
Game.child_spec("Kusama")
```

A subset of the keys will actually be returned depending on the specification chosen:

Understand the details of child specifications.

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

The Child Specification

New IEx session