Get this book at your local book store or at Amazon, Pearson, or Informit.
Component-based Rails Applications is part of the Addison-Wesley Professional Ruby Series which, among others, includes books such as The Rails 5 Way by Obie Fernandez, Practical Object-Oriented Design by Sandi Metz, or Ruby on Rails Tutorial: Learn Web Development with Rails by Michael Hartl.
Source Code
All the source code to the book is available on github.
Errata
Please find and submit errata to the book as github issues.