Gain insights into building fast, resource-efficient real-time applications using Elixir and Phoenix. Delve into websockets, GenStage, Phoenix Tracker, and production deployment practices for seamless user experiences.

_Real-Time Phoenix by The Pragmatic Programmer_ .png

Phoenix.tar.gz

Start in terminal

Direct start

Start in terminal with new deps

sneakers_initial

sneakers

sneakers-chromedriver

sneakers cart initial

sneakers cart

sneakers admin initial

sneakers admin

memory initial

observer

live view

react example

sneakers observer

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Tracker

In this course, you will learn how to build real-time applications that will be fast with less resource overhead. Today’s software users expect the data on their screens to reflect instantly. You will win your users’ trust by giving them a seamless application experience powered by real-time features.

This course is broken up into three parts. In Part 1, you will focus on the essential part of the real-time stack (Elixir, - Phoenix channels, websockets, and GenStage). This will set the foundation for building real-time applications.

In Part 2, you will add features to an e-commerce application that serves many users simultaneously. You will also get to work with some of the more advanced features of Phoenix, such as Phoenix Tracker.

In Part 3, you will finish the course with guidance on running real-time applications in production. The battle is only beginning when you write an application. You have to then keep it healthy and happy in production.

Building Real-time Applications with Phoenix & Elixir

# The importance of tests

Tests that are easy to read and modify are essential for having an application that any teammate can maintain in the future. These tests also help identify errors in code. 
>**Author's Note:** When I created the **`DedupeChannel`**, I discovered a bug where the pushes would happen incorrectly. The tests that I wrote revealed the bug to me. The value of well-written tests never decreases, even for experienced programmers.

# Wrapping up

Writing real-time applications requires us to consider the unreliable nature of long-lived connections. Users can disconnect at any time, so our applications must be developed with this in mind. A source of truth that lives outside of the connection lifecycle is one of the best ways to combat the challenges of unreliable connections.

Applications in production should always have multiple servers to ensure uptime, even when something goes wrong. Channels are usable across multiple servers, with only a tiny amount of work necessary to ensure everything works as expected. Distributing our application over multiple servers adds new challenges, but it can significantly improve scalability and reliability.

It’s possible to both write and test complex business logic in Channels. *Phoenix* gives us the right foundations so we can develop robust Channel tests while only needing to learn a handful of functions. These tests can ensure that complex logic such as asynchronous message processing and state is correctly implemented in a Channel.

One of the most important aspects of a scalable real-time application is ensuring that performance is good, even with many simultaneous users.

Let's highlight the main contents of this chapter.

Wrapping Up

Getting Started with Phoenix

Powering Real-time Applications with Phoenix

First Steps with Phoenix Channels

Restrict Socket and Channel Access

Dive Deep into Phoenix Channels

Avoid Performance Pitfalls

Build a Real-time Sneaker Store

Break Your Application with Acceptance Tests

Build a Real-time Shopping Cart

Track Connected Carts with Presence

Deploy Our Application to Production

Manage Real-time Resources

Hands-on with Phoenix LiveView

Single-page Applications with React

Wrap Up!

Appendix

Wrapping Up

The importance of tests