Draft: Uc3 TeeTime implementation

Implementation of UC3: Downsampling with TeeTime

Implements #26

application-teetime-commons/src/main/java/theodolite/commons/teetime/communication/KafkaRecordsReader.java

+package theodolite.commons.teetime.communication;
+
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.Properties;
+import org.apache.commons.configuration2.Configuration;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.serialization.StringDeserializer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import teetime.framework.AbstractProducerStage;
+import teetime.framework.OutputPort;
+import theodolite.commons.teetime.config.ConfigurationKeys;
+import titan.ccp.common.kafka.avro.SchemaRegistryAvroSerdeFactory;
+import titan.ccp.model.records.ActivePowerRecord;
+
+/**
+ * TeeTime Producer change to Reader.
+ *
+ */
+public class KafkaRecordsReader extends
+    AbstractProducerStage<ConsumerRecords<String, ActivePowerRecord>> {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(KafkaRecordsReader.class);
+  private final KafkaConsumer<String, ActivePowerRecord> consumer;
+  private final int commitIntervalMs;
+
+  private final OutputPort<Object> startPort = this.createOutputPort();
+
+  /**
+   * TeeTime Producer stage that reads from Kafka.
+   */
+  public KafkaRecordsReader(final Configuration kafkaconfig) {
+    super();
+    final Configuration config = kafkaconfig;
+    this.commitIntervalMs =
+        Integer.parseInt(config.getString(ConfigurationKeys.COMMIT_INTERVAL_MS));
+
+    final Properties props = new Properties();
+    props.put("application.name", config.getString(ConfigurationKeys.APPLICATION_NAME));
+    props.put("application.version", config.getString(ConfigurationKeys.APPLICATION_VERSION));
+    props.put("auto.commit.interval.ms",
+        config.getString(ConfigurationKeys.COMMIT_INTERVAL_MS));
+    props.put("bootstrap.servers",
+        config.getString(ConfigurationKeys.KAFKA_BOOTSTRAP_SERVERS));
+    props.put("group.id", "test");
+
+    final SchemaRegistryAvroSerdeFactory serdes = new SchemaRegistryAvroSerdeFactory(
+        kafkaconfig.getString(ConfigurationKeys.SCHEMA_REGISTRY_URL));
+
+    final ArrayList<String> inputTopics = new ArrayList<>();
+    inputTopics.add(config.getString(ConfigurationKeys.KAFKA_INPUT_TOPIC));
+
+    this.consumer = new KafkaConsumer<>(props, new StringDeserializer(),
+        serdes.<ActivePowerRecord>forValues().deserializer());
+
+
+    this.consumer.subscribe(inputTopics);
+  }
+
+
+  @Override
+  protected void execute() {
+    try {
+      this.runConsumer();
+    } catch (final InterruptedException e) {
+      LOGGER.error(e.toString());
+    }
+  }
+
+  private void runConsumer() throws InterruptedException {
+
+    final Duration pollTime = Duration.ofMillis(commitIntervalMs);
+
+    while (true) {
+      final ConsumerRecords<String, ActivePowerRecord> consumerRecords =
+          this.consumer.poll(pollTime);
+
+      if (!consumerRecords.isEmpty()) {
+        this.getOutputPort().send(consumerRecords);
+        this.consumer.commitAsync();
+      }
+
+      this.consumer.commitAsync();
+    }
+
+  }
+
+  @Override
+  protected void onTerminating() {
+    this.consumer.close();
+    super.onTerminating();
+  }
+
+  public OutputPort<Object> getStartPort() {
+    return startPort;
+  }
+
+}