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

Finite-state machine

Another way of defining how your actors behave is using a finite-state machine. This is a well-known method to create machines in digital circuits that work as well for Akka actors. An FSM can be described as a set of relations of this form:

State(S) x Event(E) -> Actions (A), State(S')

We can interpret these relations by saying that if we are in state S and an event E comes, then we will perform actions A and change our state to S'. Akka FSM brings some APIs to easily achieve these relations by defining different behaviors using the when function. This feature can fit several use cases, such as example aggregation of values.

In this recipe, we will explore how to use Akka FSM by implementing a simple traffic light. We will also look at how we can perform action between transitions by providing a partial function to onTransition.

Getting ready

To step through this recipe, we need to import the Hello-Akka project; all other prerequisites are the same as earlier.

How to do...