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/*-
* ============LICENSE_START=======================================================
* dmaap-kafka-client
* ================================================================================
* Copyright (C) 2023 Nordix Foundation. All rights reserved.
* ================================================================================
* 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.
* ============LICENSE_END=========================================================
*/
package org.onap.dmaap.kafka;
import java.time.Duration;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import java.util.UUID;
import org.apache.kafka.clients.CommonClientConfigs;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.KafkaException;
import org.apache.kafka.common.config.SaslConfigs;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Utility class that provides a KafkaConsumer to communicate with a kafka cluster
*/
public class OnapKafkaConsumer {
private final Logger log = LoggerFactory.getLogger(OnapKafkaConsumer.class);
private final KafkaConsumer<String, String> consumer;
private final int pollTimeout;
private final List<String> consumerTopics;
/**
*
* @param configuration The config provided to the client
*/
public OnapKafkaConsumer(IKafkaConfig configuration) {
consumerTopics = configuration.getConsumerTopics();
log.debug("Instantiating kafka consumer for topics {}", consumerTopics);
Properties props = new Properties();
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
props.put(ConsumerConfig.CLIENT_ID_CONFIG, configuration.getConsumerID() + "-consumer-" + UUID.randomUUID());
props.put(CommonClientConfigs.SECURITY_PROTOCOL_CONFIG, configuration.getKafkaSecurityProtocolConfig());
props.put(CommonClientConfigs.BOOTSTRAP_SERVERS_CONFIG, configuration.getKafkaBootstrapServers());
props.put(SaslConfigs.SASL_JAAS_CONFIG, configuration.getKafkaSaslJaasConfig());
props.put(SaslConfigs.SASL_MECHANISM, configuration.getKafkaSaslMechanism());
props.put(ConsumerConfig.GROUP_ID_CONFIG, configuration.getConsumerGroup());
props.put(ConsumerConfig.ALLOW_AUTO_CREATE_TOPICS_CONFIG, false);
props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "latest");
props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, true);
consumer = new KafkaConsumer<>(props);
pollTimeout = configuration.getPollingTimeout();
}
/**
* Poll specified topic for existing messages
*
* @return List of messages from a specific topic
*/
List<String> poll(String topicName) throws KafkaException {
List<String> msgs = new ArrayList<>();
log.debug("Polling records for topic {}", topicName);
ConsumerRecords<String, String> consumerRecordsForSpecificTopic = consumer.poll(Duration.ofSeconds(pollTimeout));
for(ConsumerRecord<String, String> rec : consumerRecordsForSpecificTopic){
if (rec.topic().equals(topicName)) {
msgs.add(rec.value());
}
}
return msgs;
}
/**
* Poll topics for existing messages
*
* @return List of messages from all subscribed topic
*/
List<String> poll() throws KafkaException {
List<String> msgs = new ArrayList<>();
log.debug("Polling all records");
ConsumerRecords<String, String> consumerRecords = consumer.poll(Duration.ofSeconds(pollTimeout));
for(ConsumerRecord<String, String> rec : consumerRecords){
msgs.add(rec.value());
}
return msgs;
}
public void subscribeConsumerToTopics() {
try {
consumer.subscribe(consumerTopics);
}
catch (KafkaException e) {
log.error("Failed to subscribe to given topic(s) {} : {}", consumerTopics, e.getMessage());
throw e;
}
}
}
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