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Re: KafkaProducer with generic (Avro) serialization schema


Hi Bill,

Thanks for your answer. However this proposal isn't going to solve my issue, since the problem here is that the context bounds I need to give in order to serialize it to Avro (SchemaFor, ToRecord and FromRecord) aren't serializable classes. This results in Flink not being able to serialize the KafkaProducer failing the whole job. 

Thanks,
Wouter

Op do 26 apr. 2018 om 00:42 schreef Nortman, Bill <William.Nortman@xxxxxxxxx>:

The things I would try would first in you are you class Person and Address have getters and setters and a no argument constructor.

 

From: Wouter Zorgdrager [mailto:zorgdragerw@xxxxxxxxx]
Sent: Wednesday, April 25, 2018 7:17 AM
To: user@xxxxxxxxxxxxxxxx
Subject: KafkaProducer with generic (Avro) serialization schema

 

Dear reader,

 

I'm currently working on writing a KafkaProducer which is able to serialize a generic type using avro4s.

However this serialization schema is not serializable itself. Here is my code for this:

 

The serialization schema:

class AvroSerializationSchema[IN : SchemaFor : FromRecord: ToRecord] extends SerializationSchema[IN] {

 

  override def serialize(element: IN): Array[Byte] = {

    val byteArray = new ByteArrayOutputStream()

    val avroSer = AvroOutputStream.binary[IN](byteArray)

    avroSer.write(element)

    avroSer.flush()

    avroSer.close()

 

    return byteArray.toByteArray

  }

}

 

The job code:

case class Person(name : String, age : Int, address : Address)

case class Address(city : String, street : String)

 

class SimpleJob {

 

  @transient

  private lazy val serSchema : AvroSerializationSchema[Person] = new AvroSerializationSchema[Person]()

 

  def start() = {

    val testPerson = Person("Test", 100, Address("Test", "Test"))

 

    val env = StreamExecutionEnvironment.getExecutionEnvironment

 

    env.

      fromCollection(Seq(testPerson)).

      addSink(createKafkaSink())

 

    env.execute("Flink sample job")

  }

 

 

  def createKafkaSink() : RichSinkFunction[Person] = {

    //set some properties

    val properties = new Properties()

    properties.put("bootstrap.servers", "127.0.0.01:9092")

    properties.put("zookeeper.connect", "127.0.0.1:2181")

 

    new FlinkKafkaProducer011[Person]("persons", serSchema, properties)

  }

 

}

 

The code does compile, however it gives the following error on runtime: InvalidProgramException: Object org.apache.flink.streaming.util.serialization.KeyedSerializationSchemaWrapper@639c2c1d is not serializable.

 

I assume this means that my custom SerializationSchema is not serializable due to the use of SchemaFor, FromRecord and ToRecord. 

Anyone knows a solution or workaround?

 

Thanks in advance!

Wouter

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