Book Image

Mastering Elixir

By : André Albuquerque, Daniel Caixinha
Book Image

Mastering Elixir

By: André Albuquerque, Daniel Caixinha

Overview of this book

Running concurrent, fault-tolerant applications that scale is a very demanding responsibility. After learning the abstractions that Elixir gives us, developers are able to build such applications with inconceivable low effort. There is a big gap between playing around with Elixir and running it in production, serving live requests. This book will help you fll this gap by going into detail on several aspects of how Elixir works and showing concrete examples of how to apply the concepts learned to a fully ?edged application. In this book, you will learn how to build a rock-solid application, beginning by using Mix to create a new project. Then you will learn how the use of Erlang's OTP, along with the Elixir abstractions that run on top of it (such as GenServer and GenStage), that allow you to build applications that are easy to parallelize and distribute. You will also master supervisors (and supervision trees), and comprehend how they are the basis for building fault-tolerant applications. Then you will use Phoenix to create a web interface for your application. Upon fnishing implementation, you will learn how to take your application to the cloud, using Kubernetes to automatically deploy, scale, and manage it. Last, but not least, you will keep your peace of mind by learning how to thoroughly test and then monitor your application.
Table of Contents (18 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
5
Demand-Driven Processing
Index

The Plug specification


Plug is a very central component of Phoenix, and as is stated in the documentation, lives at the heart of Phoenix's HTTP layer. The plug specification allows us to compose modules in web applications, abstracting the concept of a connection. Plug embraces the functional nature of Elixir and handles web requests by making a series of transformations on the connection, which eventually will be used to render the response.

There are two types of plugs: function plugs and module plugs. Regardless of the type, Plug's specification is very simple: a Plug must accept a connection and return a (possibly) modified connection. Later in this section, we'll explore what a connection is. Reading this elementary description, it's hard to imagine that Plug is at the heart of Phoenix. However, this simple concept is incredibly powerful, which becomes evident when you start to chain plugs together to achieve sophisticated functionality. Many of Phoenix's powerful constructs, such as...