gemfire-spark-connector/gemfire-spark-demos/basic-demos/src/main/java/demo/RDDSaveJavaDemo.java

package demo;

import io.pivotal.gemfire.spark.connector.GemFireConnectionConf;
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.PairFunction;
import scala.Tuple2;

import java.util.ArrayList;
import java.util.List;

import static io.pivotal.gemfire.spark.connector.javaapi.GemFireJavaUtil.*;

/**
 * This Spark application demonstrates how to save a RDD to GemFire using GemFire Spark
 * Connector with Java.
 * <p/>
 * In order to run it, you will need to start GemFire cluster, and create the following region
 * with GFSH:
 * <pre>
 * gfsh> create region --name=str_int_region --type=REPLICATE \
 *         --key-constraint=java.lang.String --value-constraint=java.lang.Integer
 * </pre>
 *
 * Once you compile and package the demo, the jar file basic-demos_2.10-0.5.0.jar
 * should be generated under gemfire-spark-demos/basic-demos/target/scala-2.10/.
 * Then run the following command to start a Spark job:
 * <pre>
 *   <path to spark>/bin/spark-submit --master=local[2] --class demo.RDDSaveJavaDemo \
 *       <path to>/basic-demos_2.10-0.5.0.jar <locator host>:<port>
 * </pre>
 *
 * Verify the data was saved to GemFire with GFSH:
 * <pre>gfsh> query --query="select * from /str_int_region.entrySet"  </pre>
 */
public class RDDSaveJavaDemo {

  public static void main(String[] argv) {

    if (argv.length != 1) {
      System.err.printf("Usage: RDDSaveJavaDemo <locators>\n");
      return;
    }

    SparkConf conf = new SparkConf().setAppName("RDDSaveJavaDemo");
    conf.set(GemFireLocatorPropKey, argv[0]);
    JavaSparkContext sc = new JavaSparkContext(conf);

    List<String> data = new ArrayList<String>();
    data.add("abcdefg");
    data.add("abcdefgh");
    data.add("abcdefghi");
    JavaRDD<String> rdd =  sc.parallelize(data);

    GemFireConnectionConf connConf = GemFireConnectionConf.apply(conf);

    PairFunction<String, String, Integer> func =  new PairFunction<String, String, Integer>() {
      @Override public Tuple2<String, Integer> call(String s) throws Exception {
        return new Tuple2<String, Integer>(s, s.length());
      }
    };

    javaFunctions(rdd).saveToGemfire("str_int_region", func, connConf);

    sc.stop();
  }
  
}