Book Image

Scala Reactive Programming

By : Rambabu Posa
Book Image

Scala Reactive Programming

By: Rambabu Posa

Overview of this book

Reactive programming is a scalable, fast way to build applications, and one that helps us write code that is concise, clear, and readable. It can be used for many purposes such as GUIs, robotics, music, and others, and is central to many concurrent systems. This book will be your guide to getting started with Reactive programming in Scala. You will begin with the fundamental concepts of Reactive programming and gradually move on to working with asynchronous data streams. You will then start building an application using Akka Actors and extend it using the Play framework. You will also learn about reactive stream specifications, event sourcing techniques, and different methods to integrate Akka Streams into the Play Framework. This book will also take you one step forward by showing you the advantages of the Lagom framework while working with reactive microservices. You will also learn to scale applications using multi-node clusters and test, secure, and deploy your microservices to the cloud. By the end of the book, you will have gained the knowledge to build robust and distributed systems with Scala and Akka.
Table of Contents (16 chapters)

Scala Future API callbacks

So far, we have demonstrated some of the useful ways to create a Scala Future and a Promise and displayed the results, using plain println statements. It's for understanding purposes only. In real-time projects, we don't use this approach.

We use the Scala Future API callback methods to check the following things from a Future object or a Promise object:

  • Whether it is completed with a success result
  • Whether it is completed with a failure
  • Whether it is completed successfully or not completed

We use the following functions to check the preceding things, respectively:

  • onSuccess (deprecated from Scala 2.12.0 onwards)
  • onFailure (deprecated from Scala 2.12.0 onwards)
  • onComplete

This example is about how to use a Scala Future's onComplete callback function. It refers to the scala.util.Try construct to check the Future value or exception...