Book Image

Learning Concurrent Programming in Scala - Second Edition

By : Aleksandar Prokopec
Book Image

Learning Concurrent Programming in Scala - Second Edition

By: Aleksandar Prokopec

Overview of this book

Scala is a modern, multiparadigm programming language designed to express common programming patterns in a concise, elegant, and type-safe way. Scala smoothly integrates the features of object-oriented and functional languages. In this second edition, you will find updated coverage of the Scala 2.12 platform. The Scala 2.12 series targets Java 8 and requires it for execution. The book starts by introducing you to the foundations of concurrent programming on the JVM, outlining the basics of the Java Memory Model, and then shows some of the classic building blocks of concurrency, such as the atomic variables, thread pools, and concurrent data structures, along with the caveats of traditional concurrency. The book then walks you through different high-level concurrency abstractions, each tailored toward a specific class of programming tasks, while touching on the latest advancements of async programming capabilities of Scala. It also covers some useful patterns and idioms to use with the techniques described. Finally, the book presents an overview of when to use which concurrency library and demonstrates how they all work together, and then presents new exciting approaches to building concurrent and distributed systems. Who this book is written for If you are a Scala programmer with no prior knowledge of concurrent programming, or seeking to broaden your existing knowledge about concurrency, this book is for you. Basic knowledge of the Scala programming language will be helpful.
Table of Contents (19 chapters)
Learning Concurrent Programming in Scala - Second Edition
About the Author
About the Reviewers
Customer Feedback

Creating Observable objects

In this section, we will study various ways of creating Observable objects. We will learn how to subscribe to different kinds of event produced by Observable instances and learn how to correctly create custom Observable objects. Finally, we will discuss the difference between cold and hot observables.

An Observable object is an object that has a method called subscribe, which takes an object called an observer as a parameter. The observer is a user-specified object with custom event-handling logic. When we call the subscribe method with a specific observer, we can say that the observer becomes subscribed to the respective Observable object. Every time the Observable object produces an event, its subscribed observers get notified.

The Rx implementation for Scala is not a part of the Scala standard library. To use Rx in Scala, we need to add the following dependency to our build.sbt file:

libraryDependencies += 
  "" % "rxjava-scala" % "0.19...