Could not parse. Unknown encoding. Invalid content type or spec version

Hi,

I am trying to parse events published by Kafka. These events are audit events, that are published by Kafka Brokers in case of for example, an authentication attempt.

Here are the details of the event:

Header contains :

content-type : application/cloudevents+json

Value Contains:

{
  "data" : { 
    "serviceName" : "crn:///kafka=JAlahGL_TUmLkqN_24KC2A",
    "methodName" : "kafka.Authentication",
    "resourceName" : "crn:///kafka=JAlahGL_TUmLkqN_24KC2A",
    "authenticationInfo" : {
      "principal" : "User:kafka",
      "metadata" : {
        "mechanism" : "SASL_PLAINTEXT/SCRAM-SHA-256",
        "identifier" : "kafka"
      }
    },
    "requestMetadata" : {
      "client_address" : "/10.44.168.161"
    },
    "result" : {
      "status" : "SUCCESS",
      "message" : ""
    }
  },
  "id" : "84040a3c-e5d4-46ea-b92d-462b020c86f8",
  "source" : "crn:///kafka=JAlahGL_TUmLkqN_24KC2A",
  "specversion" : "1.0",
  "type" : "io.confluent.kafka.server/authentication",
  "datacontenttype" : "application/json",
  "subject" : "crn:///kafka=JAlahGL_TUmLkqN_24KC2A",
  "time" : "2021-06-21T13:48:42.377Z",
  "confluentRouting" : {
    "route" : "confluent-audit-log-events"
  }
}

When I try to deserialize this message in a Kafka Consumer, using CloudEventDeserializer.class

props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, CloudEventDeserializer.class);

It throws an exception :

org.apache.kafka.common.errors.SerializationException: Error deserializing key/value for partition audit-producer-topic-1-0 at offset 6. If needed, please seek past the record to continue consumption.
Caused by: io.cloudevents.rw.CloudEventRWException: Could not parse. Unknown encoding. Invalid content type or spec version
	at io.cloudevents.rw.CloudEventRWException.newUnknownEncodingException(CloudEventRWException.java:201)
	at io.cloudevents.core.message.impl.MessageUtils.parseStructuredOrBinaryMessage(MessageUtils.java:80)

Upon inspection of the MesasgeUtils.java class, it has the following check

public static MessageReader parseStructuredOrBinaryMessage(Supplier<String> contentTypeHeaderReader, Function<EventFormat, MessageReader> structuredMessageFactory, Supplier<String> specVersionHeaderReader, Function<SpecVersion, MessageReader> binaryMessageFactory) throws CloudEventRWException {
        String ct = (String)contentTypeHeaderReader.get();
        if (ct != null) {
            EventFormat format = EventFormatProvider.getInstance().resolveFormat(ct);
            if (format != null) {
                return (MessageReader)structuredMessageFactory.apply(format);
            }

            if (ct.startsWith("application/cloudevents")) {
                throw CloudEventRWException.newUnknownEncodingException();
            }
        }

According to documentation, application/cloudevents+json is a valid content type, then why is an exception being thrown for that?

Any explanation around this would be useful…

Thanks in advance !!

[sumitbaurai]

Hi, Indeed including the jackson dependency resolves the deserialization issue.

[slinkydeveloper]

Can you try to debug the EventFormatProvider and see if the JsonFormat is loaded inside it? From the stacktrace, the error seems to be that you don’t have the JsonFormat loaded properly…