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

Creating a singleton actor across clusters

In some scenarios, it is required for you to have a singleton object within your whole cluster. The Akka Cluster Singleton module provides means to accomplish this task in an easy way.

This module picks the oldest node in the cluster to create your singleton actor. If this node gets removed from the cluster, then the module uses the same logic to decide where to deploy your singleton actor. First, it selects the oldest node in the cluster to recreate your singleton actor. Second, the module ensures that there is only one instance of your actor running within the whole cluster.

To demonstrate this behavior, we will make use of Auto Downing. This feature of Akka Cluster automatically marks a node Down and removes it from the cluster after a configurable amount of time. This feature is off by default.

Getting ready

For this recipe, we will set up a cluster of two nodes running on the same machine. For this, we will use two different ports specified in...