Re: pojo warning when using auto generated protobuf class

[Yun Gao]

Hi Prashant,

I think the warn is given when calling 

return TypeInformation.of(Trace.APITrace::class.java)

Currently flink does not have the native support 
for the protobuf types yet[1], thus it would use a
generic serializer created by kryo. 

This should not affect the rightness of the program
and should only affect its performance. One possible
solution might be register custom serializer into the kryo 
serializer framework for protobuf classes, like the example in [2].

Best,
Yun

[1] https://issues.apache.org/jira/browse/FLINK-11333
[2] 
https://ci.apache.org/projects/flink/flink-docs-stable/dev/custom_serializers.html


 ------------------Original Mail ------------------
Sender:Prashant Deva <prash...@astradot.com>
Send Date:Sat Apr 24 11:00:17 2021
Recipients:User <user@flink.apache.org>
Subject:pojo warning when using auto generated protobuf class

I am seeing this warning msg when trying to use a custom protobuf de/serializer 
with kafka source with auto generated java protobuf class:

18:41:31.164 [main] INFO org.apache.flink.api.java.typeutils.TypeExtractor - 
Class class com.xx.APITrace cannot be used as a POJO type because not all 
fields are valid POJO fields, and must be processed as GenericType. Please read 
the Flink documentation on "Data Types & Serialization" for details of the 
effect on performance.

here is my serializer. What am i doing wrong?

class ApiTraceSchema: DeserializationSchema<Trace.APITrace>, 
SerializationSchema<Trace.APITrace> {

    override fun getProducedType(): TypeInformation<Trace.APITrace> {
        return TypeInformation.of(Trace.APITrace::class.java)
    }

    override fun deserialize(message: ByteArray): Trace.APITrace {
        return Trace.APITrace.parseFrom(message)
    }

    override fun isEndOfStream(nextElement: Trace.APITrace): Boolean {
        return false
    }

    override fun serialize(element: Trace.APITrace): ByteArray {
        return element.toByteArray()
    }
}