Bael 43 (#6423)

* BAEL-43: Apache Spark with Spring Cloud Data Flow

* Replaced functions with lambdas + removed unnecessary type casting.

spring-cloud-data-flow/apache-spark-job/pom.xml

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>spring-cloud-data-flow</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>apache-spark-job</artifactId>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.cloud</groupId>
+            <artifactId>spring-cloud-task-core</artifactId>
+                <version>2.0.0.RELEASE</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.spark</groupId>
+            <artifactId>spark-core_2.10</artifactId>
+            <version>1.6.2</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>log4j</groupId>
+                    <artifactId>log4j</artifactId>
+                </exclusion>
+                <exclusion>
+                    <groupId>org.slf4j</groupId>
+                    <artifactId>slf4j-log4j12</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+    </dependencies>
+
+</project>

spring-cloud-data-flow/apache-spark-job/src/main/java/com/baeldung/spring/cloud/PiApproximation.java

@@ -0,0 +1,39 @@
+package com.baeldung.spring.cloud;
+
+import org.apache.spark.SparkConf;
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.api.java.JavaSparkContext;
+import org.apache.spark.api.java.function.Function;
+import org.apache.spark.api.java.function.Function2;
+import org.apache.spark.rdd.RDD;
+
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class PiApproximation {
+    public static void main(String[] args) {
+        SparkConf conf = new SparkConf().setAppName("BaeldungPIApproximation");
+        JavaSparkContext context = new JavaSparkContext(conf);
+        int slices = args.length >= 1 ? Integer.valueOf(args[0]) : 2;
+        int n = (100000L * slices) > Integer.MAX_VALUE ? Integer.MAX_VALUE : 100000 * slices;
+
+        List<Integer> xs = IntStream.rangeClosed(0, n)
+          .mapToObj(element -> Integer.valueOf(element))
+          .collect(Collectors.toList());
+
+        JavaRDD<Integer> dataSet = context.parallelize(xs, slices);
+
+        JavaRDD<Integer> pointsInsideTheCircle = dataSet.map(integer -> {
+           double x = Math.random() * 2 - 1;
+           double y = Math.random() * 2 - 1;
+           return (x*x + y*y ) < 1 ? 1: 0;
+        });
+
+        int count = pointsInsideTheCircle.reduce((integer, integer2) -> integer + integer2);
+
+        System.out.println("The pi was estimated as:" + count / n);
+
+        context.stop();
+    }
+}

spring-cloud-data-flow/pom.xml

@@ -20,6 +20,7 @@
         <module>log-sink</module>
         <module>batch-job</module>
         <module>etl</module>
+        <module>apache-spark-job</module>
     </modules>
 
 </project>