Book Image

Scala Programming Projects

By : Mikael Valot, Nicolas Jorand
Book Image

Scala Programming Projects

By: Mikael Valot, Nicolas Jorand

Overview of this book

Scala Programming Projects is a comprehensive project-based introduction for those who are new to Scala. Complete with step-by-step instructions and easy-to-follow tutorials that demonstrate best practices when building applications, this Scala book will have you building real-world projects in no time. Starting with the fundamentals of software development, you’ll begin with simple projects, such as developing a financial independence calculator, and then advance to more complex projects, such as a building a shopping application and a Bitcoin transaction analyzer. You’ll explore a variety of Scala features, including its OOP and FP capabilities, and learn how to write concise, reactive, and concurrent applications in a type-safe manner. You’ll also understand how to use libraries such as Akka and Play. Furthermore, you’ll be able to integrate your Scala apps with Kafka, Spark, and Zeppelin, along with deploying applications on a cloud platform. By the end of the book, you’ll have a firm foundation in Java programming that’ll enable you to solve a variety of real-world problems, and you’ll have built impressive projects to add to your professional portfolio.
Table of Contents (18 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Streaming transactions to Kafka


In this section, we are going to write a program that produces a stream of the BTC/USD transactions that happen in real time. Our program will:

  1. Subscribe to the WebSocket API of Bitstamp to get a stream of transactions in JSON format.

  2. For each transaction coming in the stream, it will:

    • Deserialize it

    • Convert it to the same Transaction case class that we used in BatchProducer in the previous chapter

    • Serialize it

    • Send it to a Kafka topic

In the next section, we will use Zeppelin again with Spark Streaming to query the data streamed to the Kafka topic.

Subscribing with Pusher

Go to Bitstamp's WebSocket API for live transactions: https://www.bitstamp.net/websocket/.

You will see that this API uses a tool called Pusher channels for real-time WebSocket streaming. The API documentation provides a Pusher Key that we need to use to receive live transactions.

Pusher channels is a hosted solution for delivering a stream of messages using a publish/subscribe pattern. You can find...