Book Image

Learning Apache Spark 2

Book Image

Learning Apache Spark 2

Overview of this book

Apache Spark has seen an unprecedented growth in terms of its adoption over the last few years, mainly because of its speed, diversity and real-time data processing capabilities. It has quickly become the preferred choice of tool for many Big Data professionals looking to find quick insights from large chunks of data. This book introduces you to the Apache Spark framework, and familiarizes you with all the latest features and capabilities introduced in Spark 2. Starting with a detailed introduction to Spark’s architecture and the installation procedure, this book covers everything you need to know about the Spark framework in the most practical manner. You will learn how to perform the basic ETL activities using Spark, and work with different components of Spark such as Spark SQL, as well as the Dataset and DataFrame APIs for manipulating your data. Then, you will perform machine learning using Spark MLlib, as well as perform streaming analytics and graph processing using the Spark Streaming and GraphX modules respectively. The book also gives special emphasis on deploying your Spark models, and how they can be operated in a clustered mode. During the course of the book, you will come across implementations of different real-world use-cases and examples, giving you the hands-on knowledge you need to use Apache Spark in the best possible manner.
Table of Contents (12 chapters)

Passing functions to Spark (Java)


In Java, to create a function you will have to implement the interfaces available in the org.apache.spark.api.java function package. There are two popular ways to create such functions:

  • Implement the interface in your own class, and pass the instance to Spark.
  • Starting Java 8, you can use Lambda expressions to pass off the functions to the Spark framework.

Let's implement the preceding word count examples in Java:

Figure 2.13: Code example of Java implementation of word count (inline functions)

If you belong to a group of programmers who feel that writing inline functions makes the code complex and unreadable (a lot of people do agree to that assertion), you may want to create separate functions and call them as follows:

Figure 2.14: Code example of Java implementation of word count