concept Akka in category machine learning

This is an excerpt from Manning's book Machine Learning Systems: Designs that scale. Login to get full access to this book.

In the next chapter, I’ll introduce some of the technologies and techniques used to build reactive machine learning systems. You’ll see how reactive programming techniques allow you to deal with complex system dynamics without complex code. I’ll also introduce two powerful frameworks, Akka and Spark, that you can use to build incredibly sophisticated reactive systems easily and quickly.

To get ready to build full-scale reactive machine learning systems, you need to get familiar with a few tools from the Scala ecosystem: Scala itself, Akka, and Spark. In this book, we’ll write applications in Scala because it provides excellent support for functional programming and has been used successfully in building reactive systems of all kinds. Sometimes, you’ll find that Akka can be useful as a tool for providing resilience and elasticity through its implementation of the actor model. Other times, you’ll want to use Spark to build large-scale pipeline jobs like feature extraction and model learning. In this chapter, you’ll just start to get familiar with these tools, and beginning with chapter 3, I’ll show you how they can be used to build the various components of a reactive machine learning system.

Let’s see how you can fulfill the limited scope of your mission even with your unreliable vote database. Using Akka, create a vote writer as an actor.

Listing 2.11. Full voting app

object Voting extends App { val system = ActorSystem("voting") #1 val connection = new DatabaseConnection("http://remotedatabase") #2 val writerProps = Props(new VoteWriter(connection)) #3 val writerSuperProps = Props(new WriterSupervisor(writerProps)) #4 val votingSystem = system.actorOf(writerSuperProps) #5 votingSystem ! Vote(1, 5, "nom nom") #6 votingSystem ! Vote(2, 7, "Mikey") votingSystem ! Vote(3, 9, "nom nom") println(connection.votes) } #1 Instantiates a new actor system #2 Connects to the database #3 Creates a Props configuration object for the VoteWriter #4 Creates a Props for the WriterSupervisor #5 Creates actors from the Props objects #6 Sending messages in Akka is done using the ! method.

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