Book Image

Akka Cookbook

By : Vivek Mishra, Héctor Veiga Ortiz
Book Image

Akka Cookbook

By: Vivek Mishra, Héctor Veiga Ortiz

Overview of this book

Akka is an open source toolkit that simplifies the construction of distributed and concurrent applications on the JVM. This book will teach you how to develop reactive applications in Scala using the Akka framework. This book will show you how to build concurrent, scalable, and reactive applications in Akka. You will see how to create high performance applications, extend applications, build microservices with Lagom, and more. We will explore Akka's actor model and show you how to incorporate concurrency into your applications. The book puts a special emphasis on performance improvement and how to make an application available for users. We also make a special mention of message routing and construction. By the end of this book, you will be able to create a high-performing Scala application using the Akka framework.
Table of Contents (18 chapters)
Title Page
About the Authors
About the Reviewer
Customer Feedback

Handling failure in event sourcing

Failure is a regular thing in computer science. Systems crash. Hardware stops working. There are always some out-of-control variables that we cannot predict. However, we can assume failure will happen eventually and take some actions to deal with it. Akka persistence was designed to help ease the recovery from a failure when your actors need to maintain a state and cannot simply be restarted to start from fresh. In this recipe, we will review what happens to persistent actors when something goes wrong.

Getting ready

There are no prerequisites for this recipe.

How to do it…

The following scenarios can happen when using event sourcing and persistent actors: 

  • Cannot recover events from the journal: When creating a new persistent actor, the journal might not be available. Therefore, your actor cannot check whether it needs to recover its state. At this point, Akka persistence decides that it cannot continue, executes the onRecoveryFailure callback, and stops the...