Prompt: What does this code do?

 package kafka;

 import org.apache.beam.runners.dataflow.options.DataflowPipelineOptions;
 import org.apache.beam.sdk.Pipeline;
 import org.apache.beam.sdk.io.kafka.KafkaIO;
 import org.apache.beam.sdk.io.kafka.KafkaRecord;
 import org.apache.beam.sdk.options.Description;
 import org.apache.beam.sdk.options.PipelineOptionsFactory;
 import org.apache.beam.sdk.transforms.DoFn;
 import org.apache.beam.sdk.transforms.ParDo;
 import org.apache.beam.sdk.values.KV;
 import org.apache.kafka.common.serialization.IntegerDeserializer;
 import org.apache.kafka.common.serialization.StringDeserializer;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 public class ReadKafkaTopic {

     private static final Logger LOG = LoggerFactory.getLogger(ReadKafkaTopic.class);

     public interface ReadKafkaTopicOptions extends DataflowPipelineOptions {
         @Description("Kafka Bootstrap Server")
         String getBootstrapServer();

         void setBootstrapServer(String value);

         @Description("Kafka Topic Name")
         String getTopicName();

         void setTopicName(String value);
     }

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

         Pipeline p = Pipeline.create(options);

         p
                 .apply(KafkaIO.<Integer, String>read()
                         .withBootstrapServers(options.getBootstrapServer())
                         .withTopic(options.getTopicName())
                         .withKeyDeserializer(IntegerDeserializer.class)
                         .withValueDeserializer(StringDeserializer.class)
                 )
                 .apply("Log message", ParDo.of(new DoFn<KafkaRecord<Integer, String>, String>() {
                             @ProcessElement
                             public void processElement(ProcessContext c) {
                                 KV<Integer, String> kv = c.element().getKV();
                                 String message = String.format("Message Key: %s, Message Value: %s",
                                         kv.getKey(), kv.getValue());
                                 LOG.info(message);
                                 c.output(message);
                             }
                         })
                 );

         p.run();
     }
 }

Response: This code snippet uses the Apache Beam KafkaIO connector to read messages from a Kafka topic.

The ReadKafkaTopicOptions interface specifies the Kafka bootstrap server and topic name. The @Description annotation provides a description of each option. When running the pipeline, use the command-line arguments --bootstrapServer and --topicName to set these parameters.

     public interface ReadKafkaTopicOptions extends DataflowPipelineOptions {
         @Description("Kafka Bootstrap Server")
         String getBootstrapServer();

         void setBootstrapServer(String value);

         @Description("Kafka Topic Name")
         String getTopicName();

         void setTopicName(String value);
     }

In the main method, the PipelineOptionsFactory class creates a ReadKafkaTopicOptions object from the command-line arguments. The Pipeline.create method creates a new pipeline with the specified options.

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

         Pipeline p = Pipeline.create(options);

The pipeline reads messages from the specified Kafka topic using KafkaIO.read(). This method configures the Kafka source by providing the bootstrap server, topic name, key deserializer, and value deserializer. Then, the pipeline applies a ParDo transform to log the Kafka message key and value.

                 .apply(KafkaIO.<Integer, String>read()
                         .withBootstrapServers(options.getBootstrapServer())
                         .withTopic(options.getTopicName())
                         .withKeyDeserializer(IntegerDeserializer.class)
                         .withValueDeserializer(StringDeserializer.class)
                 )
                 .apply("Log message", ParDo.of(new DoFn<KafkaRecord<Integer, String>, String>() {
                             @ProcessElement
                             public void processElement(ProcessContext c) {
                                 KV<Integer, String> kv = c.element().getKV();
                                 String message = String.format("Message Key: %s, Message Value: %s",
                                         kv.getKey(), kv.getValue());
                                 LOG.info(message);
                                 c.output(message);
                             }
                         })
                 );

Finally, the run method executes the pipeline.

         p.run();