Prompt: What does this code do?

package gcs;

import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.io.json.JsonIO;
import org.apache.beam.sdk.options.Description;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.options.Validation;
import org.apache.beam.sdk.schemas.JavaFieldSchema;
import org.apache.beam.sdk.schemas.annotations.DefaultSchema;
import org.apache.beam.sdk.transforms.Create;

import java.io.Serializable;
import java.util.Arrays;
import java.util.List;

public class WriteJsonIO {

    @DefaultSchema(JavaFieldSchema.class)
    public static class SampleRecord implements Serializable {
        public int id;
        public String month;
        public String amount

        public SampleRecord() {
        }

        public SampleRecord(int id, String month, String amount) {
            this.id = id;
            this.month = month;
            this.amount = amount;
        }
    }

    public interface WriteJsonOptions extends PipelineOptions {

        @Description("A file path to write JSON files to")
        @Validation.Required
        String getFilePath();

        void setFilePath(String filePath);
    }

    public static void main(String[] args) {
.
        WriteJsonOptions options =
                PipelineOptionsFactory.fromArgs(args)
                        .withValidation().as(WriteJsonOptions.class);

        Pipeline p = Pipeline.create(options);

        List<SampleRecord> rows =
            Arrays.asList(
                new SampleRecord(1, "January", "$1000"),
                new SampleRecord(2, "February", "$2000"),
                new SampleRecord(3, "March", "$3000"));

        p.apply("Create Records", Create.of(rows))
            .apply(
                "Write Records to JSON File",
                    JsonIO.<SampleRecord>write(options.getFilePath())
                        .withNumShards(1));
        p.run();
    }
}

Response: This code snippet uses the Apache Beam JsonIO connector to write a list of SampleRecord objects to a JSON file.

The SampleRecord class defines the schema for the JSON records and is annotated with @DefaultSchema(JavaFieldSchema.class) to indicate that its fields should be used as the schema for the JSON records.

 @DefaultSchema(JavaFieldSchema.class)
    public static class SampleRecord implements Serializable {
        public int id;
        public String month;
        public String amount

        public SampleRecord() {
        }

        public SampleRecord(int id, String month, String amount) {
            this.id = id;
            this.month = month;
            this.amount = amount;
        }
    }

The WriteJsonOptions interface specifies command-line options for configuring the output file path. The @Description annotation provides a description of the option, and @Validation.Required indicates that the option is required.

public interface WriteJsonOptions extends PipelineOptions {

        @Description("A file path to write JSON files to")
        @Validation.Required
        String getFilePath();

        void setFilePath(String filePath);
    }

The PipelineOptionsFactory class generates PipelineOptions from command-line arguments. The Pipeline.create method creates a data pipeline, defined as a sequence of transformations to be applied to the data.

  WriteJsonOptions options =
                PipelineOptionsFactory.fromArgs(args)
                        .withValidation().as(WriteJsonOptions.class);

        Pipeline p = Pipeline.create(options);

The pipeline generates a list of SampleRecord objects and applies the Create transform to create a PCollection from this list. Subsequently, the JsonIO.write transform is used to write the PCollection to a JSON file, with the withNumShards method specifying the number of output shards.

        List<SampleRecord> rows =
            Arrays.asList(
                new SampleRecord(1, "January", "$1000"),
                new SampleRecord(2, "February", "$2000"),
                new SampleRecord(3, "March", "$3000"));

        p.apply("Create Records", Create.of(rows))
            .apply(
                "Write Records to JSON File",
                    JsonIO.<SampleRecord>write(options.getFilePath())
                        .withNumShards(1));

Finally, the code snippet invokes the Pipeline.run method to execute the pipeline.

        p.run();