com.ibm.cp4waiops.connectors.sdk.CloudEventDeserializerCustom Maven / Gradle / Ivy

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A developer SDK for creating connectors for CP4WAIOps.
There is a newer version: 2.2.8
package com.ibm.cp4waiops.connectors.sdk;

import io.cloudevents.CloudEvent;
import io.cloudevents.CloudEventData;
import io.cloudevents.core.message.MessageReader;
import io.cloudevents.kafka.KafkaMessageFactory;
import io.cloudevents.rw.CloudEventDataMapper;
import org.apache.kafka.common.header.Headers;
import org.apache.kafka.common.serialization.Deserializer;

import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;

/*
 * Based on CloudEventDeserializer, with some additional error handling for
 * deserialiation problem. The original CloudEventDeserializer, when the deserialization 
 * error occurs (e.g. if a non-CloudEvent is put in the Kafka topic) the Kafka Consumer
 * will be stuck reading the same message forever. It will not skip it. This class ensures the
 * record is skipped by returning null and not throwing an error, so the Kafka Consumer can
 * read the next record.
 * 
 * Reference source: https://github.com/cloudevents/sdk-java/blob/main/kafka/src/main/java/io/cloudevents/kafka/CloudEventDeserializer.java
 * 
 */
public class CloudEventDeserializerCustom implements Deserializer {
    /**
     * The configuration key for the {@link CloudEventDataMapper}.
     */
    public final static String MAPPER_CONFIG = "cloudevents.datamapper";

    private static final Logger logger = Logger.getLogger(CloudEventDeserializerCustom.class.getName());

    private CloudEventDataMapper mapper = null;

    @Override
    public void configure(Map configs, boolean isKey) {
        Object mapperConfig = configs.get(MAPPER_CONFIG);
        if (mapperConfig instanceof CloudEventDataMapper) {
            this.mapper = (CloudEventDataMapper) mapperConfig;
        } else if (mapperConfig != null) {
            throw new IllegalArgumentException(
                    MAPPER_CONFIG + " can be of type String or " + CloudEventDataMapper.class.getCanonicalName());
        }
    }

    @Override
    public CloudEvent deserialize(String topic, byte[] data) {
        throw new UnsupportedOperationException(
                "CloudEventDeserializer supports only the signature deserialize(String, Headers, byte[])");
    }

    @Override
    public CloudEvent deserialize(String topic, Headers headers, byte[] data) {
        try {
            MessageReader reader = KafkaMessageFactory.createReader(headers, data);
            if (mapper == null) {
                return reader.toEvent();
            } else {
                return reader.toEvent(mapper);
            }
        } catch (Exception e) {
            // This would not be reported as an error, since invalid CloudEvents
            // could occur in Kafka
            logger.log(Level.FINEST, "Invalid CloudEvent read from Kafka", e);
        }
        // Return null so reading from Kafka can continue. If this throws an error, then
        // the problematic Kafka message will be read forever and the offset won't be increased
        // This null return is to deal with the "poison pill" scenario in Java Kafka consumption
        return null;
    }

}