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https://issues.apache.org/jira/browse/BEAM-1573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15888717#comment-15888717
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peay edited comment on BEAM-1573 at 2/28/17 9:20 PM:
-----------------------------------------------------
Actually, thinking more about it, just setting the serializer class in the
Kafka properties doesn't work in terms of getting a `Write` with the correct
key/value types.
Maybe we can instead have a method along the lines of
{code:title=KafkaIO.java|borderStyle=solid}
public <ValueT> Write<K, ValueT>
withCustomKafkaValueSerializer(Serializer<ValueT> serializer) {
Map<String, Object> configUpdates =
ImmutableMap.of(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG,
serializer.getClass());
Map<String, Object> config = updateKafkaProperties(producerConfig,
TypedWrite.IGNORED_PRODUCER_PROPERTIES, configUpdates); // Do not
actually ignore the VALUE_SERIALIZER_CLASS_CONFIG property in practice
return new Write<K, ValueT>(topic, keyCoder, null, config);
}
{code}
was (Author: peay):
Actually, thinking more about it, just setting the serializer class in the
Kafka properties doesn't work in terms of getting a `Write` with the correct
key/value types.
Maybe we can instead have a method along the lines of
{code:title=KafkaIO.java|borderStyle=solid}
public <ValueT> Write<K, ValueT>
withCustomKafkaValueSerializer(Serializer<ValueT> serializer) {
Map<String, Object> configUpdates =
ImmutableMap.of(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG,
serializer.getClass());
Map<String, Object> config = updateKafkaProperties(producerConfig,
TypedWrite.IGNORED_PRODUCER_PROPERTIES, configUpdates);
return new Write<K, ValueT>(topic, keyCoder, null, config);
}
{code}
> KafkaIO does not allow using Kafka serializers and deserializers
> ----------------------------------------------------------------
>
> Key: BEAM-1573
> URL: https://issues.apache.org/jira/browse/BEAM-1573
> Project: Beam
> Issue Type: Bug
> Components: sdk-java-extensions
> Affects Versions: 0.4.0, 0.5.0
> Reporter: peay
> Assignee: Davor Bonaci
> Priority: Minor
>
> KafkaIO does not allow to override the serializer and deserializer settings
> of the Kafka consumer and producers it uses internally. Instead, it allows to
> set a `Coder`, and has a simple Kafka serializer/deserializer wrapper class
> that calls the coder.
> I appreciate that allowing to use Beam coders is good and consistent with the
> rest of the system. However, is there a reason to completely disallow to use
> custom Kafka serializers instead?
> This is a limitation when working with an Avro schema registry for instance,
> which requires custom serializers. One can write a `Coder` that wraps a
> custom Kafka serializer, but that means two levels of un-necessary wrapping.
> In addition, the `Coder` abstraction is not equivalent to Kafka's
> `Serializer` which gets the topic name as input. Using a `Coder` wrapper
> would require duplicating the output topic setting in the argument to
> `KafkaIO` and when building the wrapper, which is not elegant and error prone.
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