/* | |
* Licensed under the Apache License, Version 2.0 (the "License"); | |
* you may not use this file except in compliance with the License. | |
* You may obtain a copy of the License at | |
* | |
* http://www.apache.org/licenses/LICENSE-2.0 | |
* | |
* Unless required by applicable law or agreed to in writing, software | |
* distributed under the License is distributed on an "AS IS" BASIS, | |
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
* See the License for the specific language governing permissions and | |
* limitations under the License. | |
*/ | |
package org.apache.samoa.streams.kafka; | |
/* | |
* #%L | |
* SAMOA | |
* %% | |
* Licensed under the Apache License, Version 2.0 (the "License"); | |
* you may not use this file except in compliance with the License. | |
* You may obtain a copy of the License at | |
* | |
* http://www.apache.org/licenses/LICENSE-2.0 | |
* | |
* Unless required by applicable law or agreed to in writing, software | |
* distributed under the License is distributed on an "AS IS" BASIS, | |
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
* See the License for the specific language governing permissions and | |
* limitations under the License. | |
* #L% | |
*/ | |
import java.util.Collection; | |
import java.util.List; | |
import java.util.Properties; | |
import java.util.concurrent.ExecutionException; | |
import java.util.concurrent.TimeUnit; | |
import java.util.concurrent.TimeoutException; | |
import java.util.logging.Level; | |
import java.util.logging.Logger; | |
import org.apache.kafka.clients.producer.KafkaProducer; | |
import org.apache.kafka.clients.producer.ProducerRecord; | |
/** | |
* Internal class responsible for Kafka Stream handling (both consume and | |
* produce) | |
* | |
* @author pwawrzyniak | |
* @version 0.5.0-incubating-SNAPSHOT | |
* @since 0.5.0-incubating | |
*/ | |
class KafkaUtils { | |
private transient KafkaConsumerThread kafkaConsumerThread; | |
private transient KafkaProducer<String, byte[]> producer; | |
// Properties of the consumer, as defined in Kafka documentation | |
private final Properties consumerProperties; | |
private final Properties producerProperties; | |
// Timeout for Kafka Consumer | |
private long consumerTimeout; | |
/** | |
* Class constructor | |
* | |
* @param consumerProperties Properties of consumer | |
* @param producerProperties Properties of producer | |
* @param consumerTimeout Timeout for consumer poll requests | |
*/ | |
public KafkaUtils(Properties consumerProperties, Properties producerProperties, long consumerTimeout) { | |
this.consumerProperties = consumerProperties; | |
this.producerProperties = producerProperties; | |
this.consumerTimeout = consumerTimeout; | |
} | |
/** | |
* Creates new KafkaUtils from existing instance | |
* @param kafkaUtils Instance of KafkaUtils | |
*/ | |
KafkaUtils(KafkaUtils kafkaUtils) { | |
this.consumerProperties = kafkaUtils.consumerProperties; | |
this.producerProperties = kafkaUtils.producerProperties; | |
this.consumerTimeout = kafkaUtils.consumerTimeout; | |
} | |
/** | |
* Method used to initialize Kafka Consumer Thread, i.e. instantiate it and | |
* subscribe to configured topic | |
* | |
* @param topics List of Kafka topics that consumer should subscribe to | |
*/ | |
public void initializeConsumer(Collection<String> topics) { | |
kafkaConsumerThread = new KafkaConsumerThread(consumerProperties, topics, consumerTimeout); | |
kafkaConsumerThread.start(); | |
} | |
public void closeConsumer() { | |
kafkaConsumerThread.close(); | |
} | |
public void initializeProducer() { | |
// lazy instantiation | |
if (producer == null) { | |
producer = new KafkaProducer<>(producerProperties); | |
} | |
} | |
public void closeProducer(){ | |
if(producer != null){ | |
producer.close(1, TimeUnit.MINUTES); | |
} | |
} | |
/** | |
* Method for reading new messages from Kafka topics | |
* | |
* @return Collection of read messages | |
* @throws Exception Exception is thrown when consumer was not initialized | |
* or is not subscribed to any topic. | |
*/ | |
public List<byte[]> getKafkaMessages() throws Exception { | |
return kafkaConsumerThread.getKafkaMessages(); | |
} | |
public long sendKafkaMessage(String topic, byte[] message) { | |
if (producer != null) { | |
try{ | |
ProducerRecord<String, byte[]> record = new ProducerRecord(topic, message); | |
long offset = producer.send(record).get(10, TimeUnit.SECONDS).offset(); | |
producer.flush(); | |
return offset; | |
} catch(InterruptedException | ExecutionException | TimeoutException e){ | |
Logger.getLogger(KafkaUtils.class.getName()).log(Level.SEVERE, null, e); | |
} | |
} | |
return -1; | |
} | |
} |