Kafka Client encounter "Missing required configuration "value.serializer" which has no default value

[Eric Zheng]

I am using kafka-client 0.8.2.1, here is my demo code in Scala:

import org.apache.kafka.clients.producer.{KafkaProducer,ProducerRecord};

import java.util.Properties;

object KafkaDemo {

  def main(args: Array[String]) {

    println("Hello world!")

    val properties= new Properties()

    properties.put("metadata.broker.list", "localhost:9092")

    val producer = new KafkaProducer[Object, String](properties)

    producer.send(new ProducerRecord("test", "test content"))

  }

}

when I run the code, I encounter this:

[error] (run-main-0) org.apache.kafka.common.config.ConfigException: Missing required configuration "value.serializer" which has no default value.

org.apache.kafka.common.config.ConfigException: Missing required configuration "value.serializer" which has no default value.

at org.apache.kafka.common.config.ConfigDef.parse(ConfigDef.java:124)

at org.apache.kafka.common.config.AbstractConfig.<init>(AbstractConfig.java:48)

at org.apache.kafka.clients.producer.ProducerConfig.<init>(ProducerConfig.java:235)

at org.apache.kafka.clients.producer.KafkaProducer.<init>(KafkaProducer.java:129)

at KafkaDemo$.main(KafkaDemo.scala:9)

at KafkaDemo.main(KafkaDemo.scala)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:606)

But I follow the docs and find no "value.serializer" properties, anyway I do find a similar one "serializer.class" which is default to "kafka.serializer.default.encoder"

This is the url of the docs: http://kafka.apache.org/documentation.html#producerconfigs

What is happening?

[Eric Zheng]

So, am I reading the wrong docs? I check the source code of Kafka-client and found out the the property key of key serializer and value serializer are respectively "key.serializer" and "value.serializer"

    public static final String KEY_SERIALIZER_CLASS_CONFIG = "key.serializer";

    public static final String VALUE_SERIALIZER_CLASS_CONFIG = "value.serializer";

And I have no way to find "serializer.class" and "key.serializer.class" from the source code at all !

Is there anything wrong about the docs?

[Manikumar Reddy]

looks like new producer docs missing some of these mandatory config parameters.

   

http://kafka.apache.org/documentation.html#newproducerconfigs

key.serializer, value.serializer config params are mandatory.They will take instance of below class

org.apache.kafka.common.serialization.Serializer.  Some of the default implementations are available in

org.apache.kafka.common.serialization package.

Simple new producer example is here:

https://github.com/omkreddy/kafka-examples/blob/master/src/kafka/examples/producer/Producer.java

These docs are for old producer.

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[Manikumar Reddy]

yeah, new producer  Kafka API docs  are pointing to old producer configs. will correct the links.

On Sun, Mar 15, 2015 at 12:24 PM, Eric Zheng <zhengw...@gmail.com> wrote:

Wow, was I directed from Kafka API docs wrongly ? It leads me to the old configuration specification. 

Anyway it's my fault that I have not noticed the new producer configuration. Thank you kumar,  I will modify my project accordingly.

Hope the API docs be refreshed soon.

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Warmest regards!

Zheng.Weitao(郑炜韬)

University: South China University of Technology
Major : Network Engineering

Company：Tencent,Inc.

E-mail : zhengw...@gmail.com
Phone number:13570209329

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[Kostya Golikov]

Hey, Manikumar, as far as I can see docs are still lack those vital properties.

[Manikumar Reddy]

Hi,

 This got fixed in below JIRA. But new docs will be published as part of 0.8.3 release.

  https://issues.apache.org/jira/browse/KAFKA-2131

Manikumar

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