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/*-
* ============LICENSE_START=======================================================
* Copyright (C) 2016-2018 Ericsson. All rights reserved.
* Modifications Copyright (C) 2019-2020 Nordix Foundation.
* Modifications Copyright (C) 2021 Bell Canada. All rights reserved.
* Modifications Copyright (C) 2021 AT&T Intellectual Property. 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.
*
* SPDX-License-Identifier: Apache-2.0
* ============LICENSE_END=========================================================
*/
package org.onap.policy.apex.plugins.event.carrier.kafka;
import java.util.Properties;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.onap.policy.apex.core.infrastructure.threading.ThreadUtilities;
import org.onap.policy.apex.service.engine.event.ApexEventException;
import org.onap.policy.apex.service.engine.event.ApexEventReceiver;
import org.onap.policy.apex.service.engine.event.ApexPluginsEventConsumer;
import org.onap.policy.apex.service.parameters.eventhandler.EventHandlerParameters;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This class implements an Apex event consumer that receives events using Kafka.
*
* @author Liam Fallon (liam.fallon@ericsson.com)
*/
public class ApexKafkaConsumer extends ApexPluginsEventConsumer {
// Get a reference to the logger
private static final Logger LOGGER = LoggerFactory.getLogger(ApexKafkaConsumer.class);
// The Kafka parameters read from the parameter service
private KafkaCarrierTechnologyParameters kafkaConsumerProperties;
// The event receiver that will receive events from this consumer
private ApexEventReceiver eventReceiver;
/**
* {@inheritDoc}.
*/
@Override
public void init(final String consumerName, final EventHandlerParameters consumerParameters,
final ApexEventReceiver incomingEventReceiver) throws ApexEventException {
this.eventReceiver = incomingEventReceiver;
this.name = consumerName;
// Check and get the Kafka Properties
if (!(consumerParameters.getCarrierTechnologyParameters() instanceof KafkaCarrierTechnologyParameters)) {
throw new ApexEventException("specified consumer properties of type \""
+ consumerParameters.getCarrierTechnologyParameters().getClass().getName()
+ "\" are not applicable to a Kafka consumer");
}
kafkaConsumerProperties =
(KafkaCarrierTechnologyParameters) consumerParameters.getCarrierTechnologyParameters();
}
/**
* {@inheritDoc}.
*/
@Override
public void run() {
// Kick off the Kafka consumer
try (KafkaConsumer<String, String> kafkaConsumer =
new KafkaConsumer<>(kafkaConsumerProperties.getKafkaConsumerProperties())) {
kafkaConsumer.subscribe(kafkaConsumerProperties.getConsumerTopicListAsCollection());
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("event receiver for {}:{} subscribed to topics: {}", this.getClass().getName(), this.name,
kafkaConsumerProperties.getConsumerTopicList());
}
// The endless loop that receives events over Kafka
while (consumerThread.isAlive() && !stopOrderedFlag) {
try {
final ConsumerRecords<String, String> records =
kafkaConsumer.poll(kafkaConsumerProperties.getConsumerPollDuration());
for (final ConsumerRecord<String, String> dataRecord : records) {
traceIfTraceEnabled(dataRecord);
eventReceiver.receiveEvent(new Properties(), dataRecord.value());
}
} catch (final Exception e) {
LOGGER.debug("error receiving events on thread {}", consumerThread.getName(), e);
}
}
}
}
/**
* Trace a record if trace is enabled.
*
* @param dataRecord the record to trace
*/
private void traceIfTraceEnabled(final ConsumerRecord<String, String> dataRecord) {
if (LOGGER.isTraceEnabled()) {
LOGGER.trace("event received for {} for forwarding to Apex engine : {} {}",
this.getClass().getName() + ":" + this.name, dataRecord.key(), dataRecord.value());
}
}
/**
* {@inheritDoc}.
*/
@Override
public void stop() {
stopOrderedFlag = true;
while (consumerThread.isAlive()) {
ThreadUtilities.sleep(kafkaConsumerProperties.getConsumerPollTime());
}
}
}
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