Book Image

Apache Spark 2.x for Java Developers

By : Sourav Gulati, Sumit Kumar
Book Image

Apache Spark 2.x for Java Developers

By: Sourav Gulati, Sumit Kumar

Overview of this book

Apache Spark is the buzzword in the big data industry right now, especially with the increasing need for real-time streaming and data processing. While Spark is built on Scala, the Spark Java API exposes all the Spark features available in the Scala version for Java developers. This book will show you how you can implement various functionalities of the Apache Spark framework in Java, without stepping out of your comfort zone. The book starts with an introduction to the Apache Spark 2.x ecosystem, followed by explaining how to install and configure Spark, and refreshes the Java concepts that will be useful to you when consuming Apache Spark's APIs. You will explore RDD and its associated common Action and Transformation Java APIs, set up a production-like clustered environment, and work with Spark SQL. Moving on, you will perform near-real-time processing with Spark streaming, Machine Learning analytics with Spark MLlib, and graph processing with GraphX, all using various Java packages. By the end of the book, you will have a solid foundation in implementing components in the Spark framework in Java to build fast, real-time applications.
Table of Contents (19 chapters)
Title Page
Credits
Foreword
About the Authors
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Graph operations


The Graphx library provides various inbuilt operations that can be executed on Property Graphs. In this section, we will discuss those operations.

mapVertices

Similar to map transformation on RDD, mapVertices allows users to transform the vertices of graphs. The following is the signature of the mapVertices method:

mapVertices(scala.Function2<Object,VD,VD2> map, scala.reflect.ClassTag<VD2> evidence$3, scala.Predef.$eq$colon$eq<VD,VD2> eq)

To implement scala.Function2 in Java, scala.runtime.AbstractFunction2 can be used because implementing scala.Function2 in Java requires users to implement a large number of abstract methods and this generates a lot of byte code.

AbstractFunction0, AbstractFunction1, AbstractFunction2, ... were introduced to reduce the byte code generated by anonymous functions such as scala.Function0, scala.Function1, scala.Function2, ..... That is why they are kept in the scala.runtime package. We can leverage them while calling graph operations...